Sunday 27 August 2023

Ultrasound Imaging: A Closer Look at the Different Types and Their Applications

Ultrasound is a non-invasive diagnostic technique that uses high-frequency sound waves to produce images of internal organs or other structures. It is widely used in the medical field for both diagnostic and therapeutic purposes. 

Working Principle

Ultrasound waves are produced by a transducer, which can both emit ultrasound waves, as well as detect the ultrasound echoes reflected back. In most cases, the active elements in ultrasound transducers are made of special ceramic crystal materials called piezoelectrics. These materials are able to produce sound waves when an electric field is applied to them, but can also work in reverse, producing an electric field when a sound wave hits them. When used in an ultrasound scanner, the transducer sends out a beam of sound waves into the body. The sound waves are reflected back to the transducer by boundaries between tissues in the path of the beam (e.g. the boundary between fluid and soft tissue or tissue and bone). When these echoes hit the transducer, they generate electrical signals that are sent to the ultrasound scanner.


Ultrasound has a wide range of applications in medicine. 

It is commonly used for imaging internal organs such as the liver, kidneys, and heart.

 It can also be used to visualize blood flow in arteries and veins . 

In addition, ultrasound is sometimes used during surgery by placing a sterile probe into the area being operated on. 


One of the main advantages of ultrasound is that it is non-invasive and does not use ionizing radiation like X-rays or CT scans . 

It is also relatively inexpensive compared to other imaging techniques . 

Ultrasound can be performed quickly and easily at the bedside or in an outpatient setting .


It may not be able to provide detailed images of structures that are obscured by bone or gas.


There are several types of ultrasound exams depending on the area of the body being imaged. Some common types include:

- Abdominal Ultrasound: Used to visualize organs such as the liver, gallbladder, pancreas, spleen, kidneys, and bladder.

- Pelvic Ultrasound: Used to visualize organs such as the uterus, ovaries, and prostate gland.

- Transvaginal Ultrasound: A type of pelvic ultrasound that uses a special probe inserted into the vagina to obtain images.

- Obstetric Ultrasound: Used during pregnancy to monitor fetal growth and development.

- Echocardiogram: Used to visualize the heart and its blood vessels.

Advanced Parameters

There are several advanced parameters that can be measured during an ultrasound exam. These include:

A-Mode Ultrasound: The image is shown on the screen in one-dimension. A single transducer scans the body. A-mode ultrasound may be used to discover cysts or tumors.

B-Mode Ultrasound: Uses linear array transducers to simultaneously scan a plane through the body. These echoes are converted by the machine into a 2D image. This is the most commonly used ultrasound mode. B-mode has a wide range of applications.

M-Mode Ultrasound: Works similarly to a stop-motion video. This type takes a collection of A-mode or B-mode ultrasound images and uses them to create a video. M-mode allows doctors to see the amplitude of movements.

C-Mode Ultrasound: Similar to B-mode in that the images are formed in the same plane. The transducer is moved in the 2D plane at a fixed depth.

Doppler Ultrasound: Measures blood flow velocity in arteries and veins.

Elastography: Measures tissue stiffness or softness.

Contrast-enhanced Ultrasound: Uses microbubbles injected into the bloodstream to enhance visualization of blood vessels.

Saturday 26 August 2023

Magnetic Resonance Imaging | Working Principle, Clinical Application and More

 Magnetic Resonance Imaging

MRI or Magnetic Resonance Imaging is a medical imaging technique that uses a magnetic field and radio waves to create detailed images of the organs and tissues in the body. MRI is a non-invasive technique that does not use ionizing radiation, making it safer than other imaging techniques like X-rays and CT scans. 

Working Principle:

MRI works by detecting the magnetic properties of protons in the body's water and fat molecules. When a patient is placed inside an MRI machine, the machine emits a strong magnetic field that causes these protons to align with it. The machine then emits radio waves that cause the protons to spin out of alignment. When the radio waves are turned off, the protons return to their original alignment, releasing energy that can be detected by the MRI machine. This energy is then used to create detailed images of the body's internal structures.

Clinical Applications:

MRI has many clinical applications, including diagnosis of brain and spinal cord injuries, tumors, cysts, and other anomalies in various parts of the body, breast cancer screening for women who face a high risk of breast cancer, injuries or abnormalities of the joints such as the back and knee, certain types of heart problems, diseases of the liver and other abdominal organs . 


MRI has several advantages over other imaging techniques. 

It is non-invasive and does not use ionizing radiation, making it safer than X-rays and CT scans. 

It provides excellent soft tissue contrast and can produce images in multiple planes . 

Advanced parameters in MRI:

1. T1-weighted images: These images are used to highlight fat and water in the body. They are useful in detecting tumors, infections, and other abnormalities .

2. T2-weighted images: These images are used to highlight fluid-filled structures in the body, such as cysts and edema. They are also useful in detecting tumors and infections .

3. Fluid Attenuated Inversion Recovery (FLAIR): This technique is used to suppress the signal from cerebrospinal fluid (CSF) in the brain, making it easier to detect abnormalities such as tumors and inflammation .

4. Proton Density (PD) images: These images are used to highlight the density of protons in different tissues. They are useful in detecting abnormalities in the brain and musculoskeletal system .

5. Diffusion-Weighted Imaging (DWI): This technique is used to detect changes in the movement of water molecules in tissues. It is useful in detecting acute stroke, brain tumors, and other abnormalities .

6. Dynamic Contrast-Enhanced (DCE) MRI: This technique involves injecting a contrast agent into the patient's bloodstream to enhance the visibility of blood vessels and other structures. It is useful in detecting tumors and other abnormalities .

7. Magnetic Resonance Spectroscopy (MRS): This technique is used to measure the chemical composition of tissues by analyzing the signals produced by different molecules .

8. Magnetic Resonance Angiography (MRA): This technique is used to visualize blood vessels in the body without using contrast agents or invasive procedures .

9. Functional Magnetic Resonance Imaging (fMRI): This technique is used to measure changes in blood flow in the brain that occur during different mental tasks or activities. It is useful in studying brain function and mapping brain activity .

Thursday 24 August 2023

CT Scans: Uses, Working Principle and Clinical Diagnosis | A compherensive Guide

Imagine having the ability to look inside your body, gaining insights that were once hidden from plain sight. Thanks to the marvel of modern technology, this is precisely what a Computed Tomography (CT) scan offers. Let's take a unique journey into the realm of CT scans, exploring their remarkable uses, delving into their working principles, and understanding the critical clinical diagnoses they enable.

CT scans are used for a variety of reasons. They can help diagnose muscle and bone disorders, such as bone tumors and fractures. They can pinpoint the location of a tumor, infection or blood clot. They can guide procedures such as surgery, biopsy and radiation therapy. They can detect and monitor diseases and conditions such as cancer, heart disease, lung nodules and liver masses. They can monitor the effectiveness of certain treatments, such as cancer treatment. They can detect internal injuries and internal bleeding.

Working principle:

The working principle of CT scan is based on the attenuation of X-rays by different tissues in the body. The X-ray tube rotates around the patient's body while emitting a narrow beam of X-rays through the body. The detectors on the opposite side of the patient's body pick up the X-rays that pass through the body and convert them into electrical signals that are processed by a computer to produce cross-sectional images (slices) of the body.

Advanced parameters or methods used in CT scans include:

- Technical parameters: Technical parameters such as kVp, mA, rotation time and pitch can be adjusted to optimize radiation dose and image quality.

- Contrast material: Contrast material is used in contrast-enhanced CT scans to highlight blood vessels and other structures in the body.

- Dual-energy CT: Dual-energy CT scans use two different X-ray energies to differentiate between different types of tissue in the body.

- Low-dose CT: Low-dose CT scans use lower doses of radiation than standard CT scans.

- CT angiography: CT angiography is a type of CT scan that uses contrast material to visualize blood vessels in various parts of the body.

- Cardiac CT: Cardiac CT is a type of CT scan that uses contrast material to visualize the heart and its blood vessels.

Clinical diagnosis:

When it comes to clinical diagnosis done with CT scans, they are used for various purposes such as:

- Cancer diagnosis: CT scans are used to detect cancerous tumors in various parts of the body.

- Cardiac diagnosis: CT scans are used to diagnose heart disease by detecting calcium deposits in arteries.

- Lung diagnosis: CT scans are used to detect lung nodules that may be cancerous.

- Liver diagnosis: CT scans are used to detect liver masses that may be cancerous.


CT scans have many benefits that make them an important diagnostic tool in medicine. Some of the benefits of CT scans include:

- Accurate diagnosis: CT scans can detect abnormal conditions in a patient's body with great accuracy.

- Early detection: CT scans can detect medical issues early on, which can help doctors provide timely treatment.

- Reduced need for exploratory surgeries: CT scans can help doctors determine if surgery is necessary and where it should be performed.

- Improved cancer diagnosis and treatment: CT scans can help diagnose cancerous tumors in various parts of the body and monitor the effectiveness of cancer treatment.

- Reduced length of hospitalizations: CT scans can help doctors diagnose and treat medical issues quickly, which can reduce the length of hospitalizations.

- Guiding treatment of common conditions: CT scans can help guide treatment for common conditions such as injury, cardiac disease and stroke.

- Improved patient placement into appropriate areas of care: CT scans can help doctors determine the best place for patients to receive care, such as intensive care units.

CT scans are also beneficial in emergency situations. Patients can be scanned quickly so doctors can rapidly assess their condition. Emergency surgery might be necessary to stop internal bleeding. CT images show the surgeons exactly where to operate. Without this information, the success of surgery is greatly compromised. The risk of radiation exposure from CT is very small compared with the benefit of a well-planned surgery.


- Cost: CT scans can be expensive.

- Radiation Exposure: CT scans use X-rays, which expose patients to higher radiation levels than other tests.

- Misinterpretation: Errors in reading CT scans can lead to incorrect diagnoses.

- Technical Glitches: Technical issues can affect scan accuracy.

- Metallic Interference: Metal in the body can disrupt scan quality.

- Contrast Allergies: Some patients may be allergic to contrast materials used in scans.

Monday 21 August 2023

World of Infusion Pumps : A detailed blog

In the dynamic landscape of healthcare technology, infusion pumps emerge as essential tools that biomedical engineers must grasp. This comprehensive blog uncovers the realm of infusion pumps, shedding light on their applications, functioning, and the transformative advantages they offer. Tailored for biomedical engineers, let's unravel the ingenious mechanics that power these devices and their impact on modern healthcare.

Infusion Pumps: Enabling Precise and Controlled Medication Delivery

At its core, an infusion pump is a sophisticated medical device designed to deliver fluids, such as medications, nutrients, and fluids, directly into a patient's bloodstream. This controlled and precise administration ensures that the right amount of substance is delivered at the right rate, optimizing patient care.

Working Principle: A Symphony of Precision

Infusion pumps operate based on the principle of positive displacement. They use mechanisms like peristaltic pumps or syringe pumps to create pressure that propels the fluid through a catheter or needle, into the patient's bloodstream. The rate, volume, and duration of infusion are programmable, allowing for customized delivery based on the patient's needs.

Diverse Applications: From Critical Care to Chronic Management

Infusion pumps find their application in a range of medical scenarios. In critical care units, they deliver life-saving medications such as vasoactive agents or pain management drugs. During surgeries, infusion pumps maintain anesthesia and keep patients stable. In home care settings, they facilitate the controlled administration of medications for chronic conditions like diabetes or pain management.

Advantages of Infusion Pumps: Precision at its Best

1. Accurate Dosage: Infusion pumps ensure precise medication dosages, minimizing the risk of underdosing or overdosing.

2. Customizable Delivery: Healthcare providers can tailor infusion rates to match the patient's condition and needs.

3. Continuous Monitoring: Some advanced infusion pumps come with integrated monitoring features, enabling healthcare professionals to track patient response.

4. Reduced Human Error: Automation reduces the potential for human errors associated with manual administration.

5. Enhanced Safety: Infusion pumps incorporate safety mechanisms to prevent air embolism or occlusions in the delivery line.

A Glimpse into Advanced Parameters

Some infusion pumps offer advanced parameters for even more personalized care:

1. PCA (Patient-Controlled Analgesia): Allows patients to control their pain medication dosages within prescribed limits.

2. TIVA (Total Intravenous Anesthesia): Provides controlled delivery of anesthetic agents during surgeries.

3. Smart Pumps: These infusion pumps have built-in dose error reduction systems (DERS) that alert healthcare providers if a programmed dosage falls outside safe limits.

Empowering Biomedical Engineers for the Future

Biomedical engineers, your expertise holds the key to advancing infusion pump technology. From developing innovative delivery mechanisms to enhancing user interfaces, your role shapes the evolution of these vital medical devices. The fusion of engineering and healthcare transforms patient care, improving accuracy, safety, and overall outcomes.

Conclusion: Engineering Precision, Enhancing Care

Infusion pumps represent the convergence of engineering ingenuity and healthcare excellence. As biomedical engineers, you have the opportunity to drive innovation in medication delivery, enhancing the quality of patient care across the globe. Embrace the journey of discovery, empowerment, and impact, as infusion pumps continue to revolutionize healthcare delivery.

"Revolutionizing Patient Care: Exploring Advanced Monitoring Technology in Healthcare"

 A patient monitor is a medical device used in hospitals to continuously track and display vital signs of patients. It helps healthcare professionals monitor a patient's condition in real-time. The monitor typically consists of sensors that measure various physiological parameters and a screen to display the data.

Working principle:

The working principle involves sensors attached to the patient's body that detect parameters like heart rate, blood pressure, oxygen saturation, respiratory rate, and temperature. These sensors send the data to the monitor, which processes and displays the information in a readable format.

Basic parameters monitored include:

- Heart rate: Number of heartbeats per minute.

- Blood pressure: Force exerted by blood against artery walls.

- Oxygen saturation (SpO2): Percentage of oxygen bound to hemoglobin in the blood.

- Respiratory rate: Number of breaths taken per minute.

- Temperature: Body temperature measurement.

Uses of patient monitors include:

- Continuous patient monitoring in intensive care units (ICUs).

- Post-operative recovery monitoring.

- Monitoring during surgeries.

- Tracking patients with chronic conditions.

- Detecting deteriorating health conditions promptly.

Advantages of patient monitors in hospitals:

- Real-time tracking: Monitors provide immediate updates on a patient's condition.

- Early detection: Abnormalities can be spotted early, reducing the risk of complications.

- Remote monitoring: Some monitors enable healthcare professionals to monitor patients from a distance.

- Data record: Monitors generate a record of a patient's vital signs, aiding in medical history documentation.

- Treatment customization: Data helps tailor treatments to individual patient needs.

In essence, patient monitors play a crucial role in modern healthcare by facilitating continuous and accurate monitoring of patients, leading to improved patient care and outcomes.

Advanced patient monitors can detect a wide range of parameters beyond the basic ones I mentioned earlier. Some of these advanced parameters include:

1. **Cardiac Output (CO)**: This measures the amount of blood the heart pumps per minute and is useful in assessing cardiac function.

2. **End-Tidal Carbon Dioxide (EtCO2)**: This parameter indicates the concentration of carbon dioxide at the end of an exhaled breath, providing insights into a patient's ventilation and metabolism.

3. **Central Venous Pressure (CVP)**: CVP measures the pressure in the central veins, reflecting the heart's ability to pump blood effectively and the body's fluid status.

4. **Pulmonary Artery Pressure (PAP)**: PAP monitoring is crucial for patients with heart and lung conditions, as it helps assess the pressures in the pulmonary arteries.

5. **Intracranial Pressure (ICP)**: This parameter measures pressure within the skull and is vital for patients with traumatic brain injuries or other neurological conditions.

6. **Bispectral Index (BIS)**: BIS monitoring is used during anesthesia to assess the depth of sedation and monitor the level of consciousness.

7. **Cardiac Index (CI)**: Similar to cardiac output, cardiac index takes into account the patient's body size, providing a more accurate assessment of cardiac function.

8. **Stroke Volume Variation (SVV) and Pulse Pressure Variation (PPV)**: These parameters indicate fluid responsiveness and guide fluid management in critically ill patients.

9. **Tissue Oxygenation (NIRS)**: Near-infrared spectroscopy (NIRS) monitors tissue oxygen saturation in specific regions, helping assess blood perfusion.

10. **Continuous Glucose Monitoring (CGM)**: Some patient monitors incorporate CGM to monitor blood glucose levels continuously, benefiting diabetic patients.

11. **Capnography**: Capnography measures the concentration of carbon dioxide in exhaled breath, assisting in assessing ventilation and lung function.

12. **Electroencephalography (EEG)**: In advanced ICU settings, EEG monitoring can provide insights into brain activity and aid in diagnosing seizures and other neurological conditions.

These advanced parameters offer healthcare professionals more comprehensive information about a patient's condition, enabling them to make more informed decisions about treatment and care. However, it's important to note that not all patient monitors include all of these parameters, and the choice of monitoring depends on the patient's specific needs and the capabilities of the equipment available.

Sunday 20 August 2023

"Ultimate Guide to Ventilators: Modes, Clinical Uses, Top Brands, and Notable Models"

 Title: Ventilators: Modes, Uses, Clinical Applications, Brands, Notable Models, and How They Work


Ventilators have revolutionized critical care medicine by offering life-saving respiratory support to individuals who are unable to breathe adequately on their own. This blog delves into the various modes and applications of ventilators, shedding light on their importance in managing a range of clinical conditions. Additionally, we'll explore some renowned brands and their notable ventilator models that have made significant contributions to this field, along with an understanding of how these devices work.

Understanding Ventilator Modes:

Ventilators are equipped with diverse modes that cater to specific patient needs. These modes include:

1. **Assist-Control (AC) Mode**: Beneficial for patients who can't initiate breaths, AC mode delivers a preset number of breaths per minute, with each breath triggered by the patient's effort or completely controlled by the ventilator.

2. **Pressure Support (PS) Mode**: PS mode assists patients by supplying additional pressure during inhalation, easing their breathing efforts and enhancing overall ventilation.

3. **Synchronized Intermittent Mandatory Ventilation (SIMV) Mode**: Suitable for weaning patients off full ventilatory support, SIMV mode combines patient-triggered breaths with mandatory ventilator breaths.

4. **Continuous Positive Airway Pressure (CPAP) Mode**: Used to treat sleep apnea and prevent airway collapse, CPAP mode maintains a constant positive pressure in the airways.

5. **Pressure Control (PC) Mode**: Ideal for patients with specific lung conditions, PC mode delivers breaths at a predetermined pressure level.

Clinical Applications of Ventilators:

Ventilators are indispensable in managing a variety of clinical conditions, including:

1. **Acute Respiratory Distress Syndrome (ARDS)**: ARDS, often caused by conditions like pneumonia, requires aggressive ventilatory support to maintain oxygenation and minimize lung damage.

2. **Chronic Obstructive Pulmonary Disease (COPD)**: Patients with severe COPD may experience acute exacerbations, necessitating ventilator assistance to ensure adequate ventilation and oxygenation.

3. **Neuromuscular Disorders**: Conditions like muscular dystrophy or spinal cord injuries can weaken respiratory muscles, making ventilatory support crucial for maintaining proper breathing.

4. **Anesthesia Management**: During surgeries, anesthesia ventilators control patients' breathing, ensuring a stable respiratory pattern while they are under general anesthesia.

How Ventilators Work:

Ventilators work by delivering a controlled mix of air and oxygen to the patient's lungs. The process involves several key steps:

1. **Inhalation**: The ventilator generates positive pressure, causing the patient's lungs to inflate. This is the inhalation phase.

2. **Exhalation**: The ventilator then allows the pressure to drop, allowing the patient to exhale naturally or with assistance, depending on the mode.

Notable Ventilator Models from Renowned Brands:

Let's take a closer look at some ventilator models from reputable brands:

1. **Hamilton Medical**:

   - Model: Hamilton-G5

   - Features: Adaptive lung-protective ventilation, lung recruitment tools, and touchscreen interface.

2. **Philips Healthcare**:

   - Model: Philips Respironics V60

   - Features: Noninvasive and invasive ventilation modes, auto-adaptive technology, and real-time monitoring.

3. **Medtronic**:

   - Model: Puritan Bennett™ 980

   - Features: Advanced graphics display, adaptive support ventilation, and customizable therapy options.

4. **Dräger**:

Dräger's ventilator models, including Evita V800, Babylog V800 and Savina V300, are designed for critical care with advanced features, user-friendliness, and adaptable ventilation modes. These models contribute to efficient patient care and safety in critical care settings.

5. Maquet - Getinge

Maquet offers a range of advanced ventilator models, including Servo-i for critical care, Servo-n for neonatal and adult patients, Servo-air for transport, and Servo-u with versatile invasive and non-invasive capabilities. These ventilators are known for their innovation, adaptability, and patient-focused design.


Ventilators have revolutionized the way healthcare professionals manage patients with respiratory compromise. With a plethora of modes catering to specific patient needs, ventilators are indispensable in critical care units, surgical theaters, and emergency scenarios. From treating conditions like ARDS and COPD to supporting patients with neuromuscular disorders, these devices play a crucial role in maintaining proper oxygenation and ventilation. Notable ventilator models from brands like Hamilton Medical, Philips Healthcare, Medtronic, and Dräger continue to push the boundaries of ventilator technology, ensuring that patients receive the best possible respiratory support during their time of need.

What is Piston Technology in Anesthesia Machine | How it Works ?

 Piston Technology in Anesthesia Machine

Piston technology is used in some anesthesia machines to deliver gas to the patient's lungs. A piston is a disc or cylinder that moves back and forth inside a cylinder. In an anesthesia machine, the piston is driven by an electric motor. When the piston moves forward, it compresses the gas in the cylinder, which increases the pressure of the gas. This pressure difference forces the gas to flow into the patient's lungs.

Piston ventilators have several advantages over other types of ventilators, such as bellows ventilators. First, they are more precise in delivering the desired tidal volume. This is because the volume of gas delivered by a piston is directly proportional to the distance that the piston moves. Second, piston ventilators are less affected by leaks in the breathing circuit. This is because the piston does not rely on a driving gas to operate. Third, piston ventilators are more efficient in terms of oxygen consumption. This is because they do not waste oxygen by compressing it and then releasing it back into the atmosphere.

  • Precision: Piston ventilators are more precise because the volume of gas delivered is directly proportional to the distance that the piston moves. This makes them ideal for delivering small tidal volumes, such as those used in pediatric patients.
  • Leaks: Piston ventilators are less affected by leaks in the breathing circuit because they do not rely on a driving gas to operate. This is important because leaks can occur in any anesthesia system, and they can lead to inaccurate ventilation.
  • Oxygen consumption: Piston ventilators are more efficient in terms of oxygen consumption because they do not waste oxygen by compressing it and then releasing it back into the atmosphere. This is a major advantage in hospitals, where oxygen is a scarce resource.
  • Cost and complexity: Piston ventilators are more expensive and complex than bellows ventilators. This is because they require more sophisticated electronics and controls. However, the increased cost and complexity are offset by the advantages of precision, leak compensation, and oxygen efficiency.

Overall, piston technology is a promising technology for anesthesia machines. It offers several advantages over other types of ventilators, and it is becoming increasingly popular in hospitals and other healthcare settings.

Here are some specific examples of anesthesia machines that use piston technology:

Drager Anesthesia Machines

What is a decoupling valve ? | Anesthesia Machine | Benefits

  Decoupling valve 

A decoupling valve is a valve that is used in anesthesia machines to prevent fresh gas from being added to the tidal volume during inspiration. It is located between the fresh gas flow inlet and the ventilator in a circle system breathing circuit.

The decoupling valve works by closing during the inspiratory phase of mechanical ventilation, diverting the fresh gas to the reservoir bag, and preventing further addition of FGF to the inspired gas mixture. During expiration, the decoupling valve opens, allowing fresh gases that had been diverted to the reservoir bag to be added to the ventilator circuit for delivery in the next inspiration.

The decoupling valve ensures the delivery of an accurate tidal volume and prevents barotrauma and volutrauma. Barotrauma is a lung injury that can occur when the pressure in the lungs is too high. Volutrauma is a lung injury that can occur when the volume of the lungs is too large.

The decoupling valve is an important safety feature in anesthesia machines. It helps to ensure that the patient receives the correct amount of gas and prevents lung injuries.

Here are some of the benefits of using a decoupling valve:

  • It ensures the delivery of an accurate tidal volume.
  • It prevents barotrauma and volutrauma.
  • It helps to conserve fresh gas.
  • It can help to reduce the risk of contamination of the breathing circuit.

Decoupling valves are a standard feature in most modern anesthesia machines, used in Drager anesthesia machine. They are an important safety feature that helps to ensure the safe and effective delivery of anesthesia.

Tuesday 9 January 2018





1)What is Bio metrics?

Bio metrics is the measurement and statistical analysis of people’s physiological and behavioral characteristics. The technology is mainly used for identification and access control, or for identifying individuals that are under surveillance. The basic premise of bio metric authentication is that everyone is unique and an individual can be identified by his or her intrinsic physical or behavioral traits.

2)What are biometric systems?

A wide variety of systems require reliable personal recognition schemes to either confirm or determine the identity of an individual requesting their services. The purpose of such schemes is to ensure that the rendered services are accessed only by a legitimate user, and not anyone else. Biometric recognition, or simply biometrics, refers to the automatic recognition of individuals based on their physiological and/or behavioural characteristics. These systems are called as biometric systems.

3)List the types of biometric systems with example?

 Bio metrics can furthermore also be defined as either
Passive Bio metrics—Passive bio metrics do not require a users active participation and can be successful without a person even knowing that they have been analyzed. 
Eg., Voice recognition technologies

Active Bio metrics— Active bio metrics however, do require a person cooperation and will not work if they deny their participation in the process. 
Eg., Hand geometry technologies

List the processes involved in bio metric system process.
Data collection, Transmission, Signal processing, Decision and Data storage.

4)Distinguish between positive and negative
(April/May 2014) (April/May 2017) (2013 Regulation)

Positive Identification—when a bio metric system accepts a user while identification or authentication process and that is known as positive identification.

Negative Identification—when a bio metric system rejects a user while identification or authentication process and that is known as negative identification.

5)Mention the characteristics of bio metrics? 
(April/May 2014) (2013 Regulation) 

Physiological characteristics: The shape or composition of the body. Physiological bio metrics use algorithms and other methods to define identity in terms of data gathered from direct measurement of the human body. Finger print and finger scan, hand geometry, Iris and retina scanning and facial geometry are all examples of physiological bio metrics.

Behavioural characteristics: The behavior of a person. Behavioural bio metrics are, however, defined by analyzing a specific action of a person. How a person talks, signs their name or types on a keyboard is a method of determining his identity when analyzed correctly.

6)Difference between identification and verification
(Nov 2012) (2008 Regulation)

Identification (1:N system) - One to Many: Bio metrics can be used to determine a person's identity even without his knowledge or consent. For example, scanning a crowd with a camera and using face recognition technology, one can determine matches against a known database.

7)Draw the block diagram of bio metric system
(Nov 2012) (2008 Regulation)

8)What is the physical and logical context of bio metric systems? (April/May 2017) (2013 Regulation)

Physical access control covers identity authentication processes which require users to provide physical characteristics.
 It is used in high security locations such as: hospitals, police stations, and thee military.
 The most common use for the physical access control application is the access devices which are applied at doors or computers. 
This application is confidential and important and is entrusted with a high level of security. 
The physical access control reduces the risk of human problems. 
It also covers the aspect of data loss in the system. 
The system helps to eliminate the process of identifying long and complex pass codes with different processes.
 Physical access control is not only effective and efficient but also safe, secure and profitable in the workplace

Logical access control refers to a process of a scheme control over data files or computer programs. 
These contain personal or privacy information of many different users.
 Logical access control is used by militaries and governments to protect their important data with high security systems using bio metric technology. 
The only difference between logical access control and physical access control is that the logical access control is used for computer networks and system access control.
 It helps to reduce the burden of long and complex password requirements for users.
 Moreover, it is more secure and effective in the way of protecting and maintaining privacy over data in the system. Furthermore, it also provides a great advantage by saving time and money
List few applications of biometric systems.

  • Justice/law enforcement
  • Time and attendance
  • Security locks
  • Physical access control
  • Logical access control



1)Explain ‘Verification and identification’ in bio metric system. (April/May 2017) (2013 Regulation)

Bio metrics is the measurement and statistical analysis of people’s physiological and behavioural characteristics.

The technology is mainly used for identification and access control, or for identifying individuals that are under surveillance. The basic premise of bio metric authentication is that everyone is unique and an individual can be identified by his or her intrinsic physical or behavioural traits.

Active and passive biometrics
Biometrics can furthermore also be defined as either

  1. Passive Biometrics, or
  2. Active Bio metrics.

Passive Bio metrics

Passive bio metrics do not require a users active participation and can be successful without a person even knowing that they have been analyzed. 
  • Voice recognition technologies
  • Iris recognition technologies
  • Facial recognition

Active Bio metrics:

Active bio metrics however, do require a person cooperation and will not work if they deny their participation in the process.

  • All Fingerprint technologies
  • Hand geometry technologies
  • Retina scanning technologies
  • Signature recognition technologies

Identification (1:N system) - One to Many: Bio metrics can be used to determine a person's identity even without his knowledge or consent. For example, scanning a crowd with a camera and using face recognition technology, one can determine matches against a known database.

Verification (1:1 system) - One to One: Bio metrics can also be used to verify a person's identity. For example, one can grant physical access to a secure area in a building by using finger scans or can grant access to a bank account at an ATM by using retinal scan.

2)With suitable diagram explain the process of matching in bio metric system. (April/May 2017) (2013 Regulation)

The comparison of bio metric templates to determine their degree of similarity or correlation is called matching. The process of matching bio metric templates results in a score, which, in most systems, is compared against a threshold. If the score exceeds the threshold, the result is a match; if the score falls below the threshold, the result is a non match.

The matching process involves the comparison of a verification template, created when the user provides bio metric data, with the enrollment template(s) stored in a bio metric system. 
In verification systems, a verification template is matched against a user’s enrollment template or templates (a user may have more than one bio metric template enrolled—for example, multiple fingerprints or iris patterns).
 In identification systems, the verification template can be matched against dozens, thousands, even millions of enrollment templates. 
The following are steps in involved in matching.

Scoring Bio metric match/no-match decisions are based on a score—a number indicating the degree of similarity or correlation resulting from the comparison of enrollment and verification templates. 
Bio metric systems utilize proprietary algorithms to process templates and generate scores. 
There is no standard scale used for bio metric scoring: Some bio metric systems employ a scale of 1 to 100; others use a scale of -1 to 1. 
These scores can be carried out to several decimal points and can be logarithmic or linear.
 Scoring systems vary not only from technology to technology, but from vendor to vendor.

Threshold Once a score is generated, it is compared to the verification attempt’s threshold. A threshold is a predefined number, generally chosen by a system administrator, which establishes the degree of correlation necessary for a comparison to be deemed a match. If the score resulting from template comparison exceeds the threshold, the templates are a match (though the templates themselves are not identical). Thresholds can vary from user to user, from transaction to transaction, and from verification attempt to verification attempt. Systems can be either highly secure or not secure at all, depending on their threshold settings. The flexibility offered by the combination of scoring and thresholds allows bio metrics to bee deployed in ways not possible with passwords, PINs, or tokens. For example, a system can be designed that employs a high security threshold for valuable transactions and a low security threshold for low-value transactions—the underlying comparison is transparent to the user.

Decision. The result of the comparison between the score and the threshold is a decision. The decisions a bio metric system can make include match, non match, and inconclusive, although varying degrees of strong matches and non matches are possible. Depending on the type of biometric system deployed, a match might grant access to resources, a non match might limit access to resources, while inconclusive may prompt the user to provide another sample. Therefore, for most technologies, there is simply no such thing as a 100 percent match. This is not to imply that the systems are not secure—biometric systems may be able to verify identity with error rates of less than 1 in 100,000 or 1 in 1 million. However, claims of 100 percent accuracy are misleading and are not reflective of the technology’s basic operation.

3)Explain security and privacy in bio metrics.

i)Unlike more common forms of identification, bio metric measures contain no personal information and are more difficult to forge or steal.

ii)Bio metric measures can be used in place of a name or Social Security number to secure anonymous transactions.

iii)Some bio metric measures (face images, voice signals and “latent” fingerprints left on surfaces) can be taken without a person’s knowledge, but cannot be linked to an identity without a pre-existing in-vertible database.

iv)A Social Security or credit card number, and sometimes even a legal name, can identify a person in a large population. This capability has not been demonstrated using any single bio metric measure.

v)Like telephone and credit card information, bio metric databases can be searched outside of their intended purpose by court order.

vi)Unlike credit card, telephone or Social Security numbers, bio metric characteristics change from one measurement to the next.

vii)Searching for personal data based on bio metric measures is not as reliable or efficient as using better identifiers, like legal name or Social Security number.

viii)Bio metric measures are not always secret, but are sometimes publicly observable and cannot be revoked if compromised.
Whenever bio metric identification is discussed, people always want to know about the implications for personal privacy.
 If a bio metric system is used, will the government, or some other group, be able to get personal information about the users? 
Bio metric measures themselves contain no personal information. 
Hand shape, fingerprints or eye scans do not reveal name, age, race, gender, health or immigration status. Although voice patterns can give a good estimation of gender, no other bio metric identification technology currently used reveals anything about the person being measured. More common identification methods, such as a driver’s license, reveal name, address, age, gender, vision impairment, height and even weight! Driver’s licenses, however, may be easier to steal or counterfeit than bio metric measures.
Bio metric measures can be used in place of a name, Social Security number or other form of identification to secure anonymous transactions.
 Walt Disney World sells season passes to buyers anonymously, then uses finger geometry to verify that the passes are not being transferred. 
Use of iris or fingerprint recognition for anonymous health care screening has also been proposed. 
A patient would use an anonymous bio metric measure, not a name or Social Security number, when registering at a clinic. All records held at the clinic for that patient would be identified, linked and retrieved only by the measure.
 No one at the clinic, not even the doctors, would know the patient’s “real” (publicly recognized) identity.

4)What is biometrics? Explain its different types and its characteristics.

Biometrics is the measurement and statistical analysis of people’s physiological and behavioural characteristics.

The technology is mainly used for identification and access control, or for identifying individuals that are under surveillance. The basic premise of biometric authentication is that everyone is unique and an individual can be identified by his or her intrinsic physical or behavioural traits.
There are two main types of biometric identifiers:

1.  Physiological characteristics: The shape or composition of the body.

Physiological biometrics use algorithms and other methods to define identity in terms of data gathered from direct measurement of the human body. Finger print and finger scan, hand geometry, Iris and retina scanning and facial geometry are all examples of physiological biometrics.

Behavioural characteristics: The behaviour of a person.

Behavioural bio metrics are, however, defined by analyzing a specific action of a person. How a person talks, signs their name or types on a keyboard is a method of determining his identity when analyzed correctly.

The ideal bio metric characteristic has five qualities:
  • Robustness,
  • Distinctiveness,
  • Availability,
  • Accessibility and
  • Acceptability.

By “robust”, we mean unchanging on an individual over time. Robustness is measured by the “false non-match rate” (also known as “Type I error”), the probability that a submitted sample will not match the enrollment image.

By “distinctive”, we mean showing great variation over the population. Distinctiveness is measured by the “false match rate” (also known as “Type II error”) – the probability that a submitted sample will match the enrollment image of another user.

By “available”, we mean that the entire population should ideally have this measure in multiples. Availability is measured by the “failure to enroll” rate, the probability that a user will not be able to supply a readable measure to the system upon enrollment.

By “accessible”, we mean easy to image using electronic sensors. Accessibility can be quantified by the “throughput rate” of the system, the number of individuals that can be processed in a unit time, such as a minute or an hour.

By “acceptable”, we mean that people do not object to having this measurement taken from them. Acceptability is measured by polling the device users. The first four qualities are inversely related to their above measures, a higher “false non-match rate”, for instance, indicating a lower level of robustness.

System administrators might ultimately be concerned with:

The “false rejection rate”, which is the probability that a true user identity claim will be falsely rejected, thus causing inconvenience;

The “false acceptance rate”, which is the probability that a false identity claim will be accepted, thus allowing fraud;

The system throughput rate, measuring the number of users that can be processed in a time period;

The user acceptance of the system, which may be highly dependent upon the way the system is “packaged” and marketed; and

The ultimate total cost savings realized from implementing the system.

5)Explain about data acquisition, enrollment, template creation and matching in a bio metric system.

A bio metric system is a technological system that uses information about a person (or other biological organism) to identify that person. Bio metric systems rely on specific data about unique biological traits in order to work effectively. A biometric system will involve running data through algorithms for a particular result, usually related to a positive identification of a user or other individual.

  1. Data collection,
  2. Transmission,
  3. Signal processing,
  4. Decision and
  5. Data storage.

A biometric system can be either an 'identification' system or a 'verification' (authentication) systemm, which are defined below.

Identification (1:N system) - One to Many: Biometrics can be used to determine a person's identity even without his knowledge or consent. For example, scanning a crowd with a camera and using face recognition technology, one can determine matches against a known database.
Verification (1:1 system) - One to One: Biometrics can also be used to verify a person's identity. For example, one can grant physical access to a secure area in a building by using finger scans or can grant access to a bank account at an ATM by using retinal scan.

6)Explain any two bio metric applications with suitable diagrams.

Thursday 4 January 2018


Unit 1
1. Describe in details about  Newton law of motion?( M/J 2014)
Newton’s law :
Since the muscle skeletal system is simply a series of objects in contact with each other , some of the basics physics principles developed by sir Isaac Newton.
Newton’s law are as follows:
Newton's First law  : An object remains at rest (on continues moving at a constant velocity ) unless acted upon by an unbalance external force.
Newton's first law is called the Law of  Inertia because it outlines a key property of matter related to motion.

Newton's second law : If there is an unbalanced force acting an a object it produces an acceleration in the direction of the force directly proportional to force (F=ma).
Newton's second law is arguably the most  important law of motion because it shows how the forces that create motion (kinetics) are linked to the motion (kinematics). The second law is called the Law of Momentum or Law of Acceleration.

Newton's Third law: For every action (force) there is a reaction (opposite force)of equal magnitude but  in the opposite direction.
From the first law It is clear that if a body is at   rest there can be no unbalanced external force acting on it.In this situation ,termed  static equilibrium ,all the external forces acting on a body must add to zero.
An extension of this law to objects larger than a particle is that the sum of the external moments acting on that body must also be equal to zero for the body to be rest.
Moments (m) is typically caused by the force(f) acting at a distance ® from the center of relation of a segment  .A moment lends to cause a rotation and is defined by the cross product function M=r X f.
For 3D Analysis there are a total of six equations that must satisfied for static for static equilibrium.
F x = 0                       F y= 0             F z = 0

M x = 0                       M y= 0          M z = 0

For 2D analysis there are only two in plane force components & one perpendicular moments (torque) components:
F x = 0                       F y= 0             M z = 0

When the body is not in static equilibrium Newton’s  second law state that the unbalanced force and moments are proportional to the acceleration of the body.

2. Derive the Euler’s equation .(N/D2014)

A fluid in equilibrium is not affected by an shearing stress that is there is there are no forces acting in the horizontal direction .It the fluid is in motion these forces will be important  as a result of the viscosity of fluid .let us consider initially an ideal fluid for which the viscosity forces the only stress that has to be considered in the fluid is the normal stress or pressure P.pressure is a scalar quantity and a function of a space coordinates and time,p(x,y,z,t).
In the simplest cases the fluid particle move in layer or sheet ,which constitute a laminar flow .If the particle trajectories are irregular the flow is turbulent.
Consider non rotational fluds,I n which the angular velocity fluids ,in which the deformation is negible.
Let us consider again a volume V in the fluid .the total force acting on this volume due to the interactions with the remaining fluid particles is  

Where –v e sign is due to the fact that the Forces acts on the  consider element ,to a scalar quality A, we have
Therefore the force by the remaining part of the fluid on the volume element dv is -p dv,and the force per unit volume is simply -p.
We can express the momentum conservation by.
                   ɐ X acceleration =-p.
where  ɐ is again the fluid density .In the care of a particle of mass m underthe action of a force and moving with velocity v,the acceleration is simply a=F/M =dv/dt. for a fluids particle the velocity variation has two components :
dv1=   __d v ___      d t
                 d t
which refer to the velocity variation at a fixed point in space that is having constant coordinates x,y,z in a time Val dt and
  dv2=  dx  ∂v∂x  +   dy   ∂v∂y +  dz   ∂v∂z
which refers to the velocity variation at a given time  between two different points in space separated by
                                   d r=dxi+dyj+d2k
which is the distance covered by the fluid particle in time dt(I,j,k are the unit vectors of the direction x,y,z)recalling tha
    =ddx   i+ddy   j+   ddz kwe have
    dv2=  dx  ddx  +   dy   ddy +  dz   ddz
the total variation dv is
dv =dv1+dv2 =dvdtdt+(dr.∇)v
the acceleration is them
acceleration =dvdt + (v.) v
this derivation is called total derivation which is usually represented.
D  Dt  =ddt+(v.)
The descrption of the fluid motion considering separately two terms,that is d/dt
In a fixed position and v, in given time corresponds to eulerian description on the other hand the description of the  fluid motion in terms of the total derivative D/Dt  corresponds to the lagrangian description .In this case we can imagine that we are following the motion of a fluid element .
Naleirally  the lagrangian derivative D/Dt is related to eulerian derivatives

                     e   X   [dvdt + (v.) v   ] = -p

                        dvdt  +  (v.)  v    -1e  p

                       D  Dt   =-1e  p
Different form of euler equation.
An important application of the equation of motion occurs when the fluid is in a gravitation fluid   characterized by the acceleration (force per unit mass)g .In this case each volume unit is under the action of the force eg  which is the  gravitational force acting per unit volume so that the equation of motion is written as.
                        dvdt  + (v.)  v    -1e  p+g
More generally if the fluid is under the action of an external force field F(dyn/cm’)that is F is the force acting on a unit volume we have
               dvdt  + (v.)  v    -1e  p+   1e   f
This is the Eulers equation.

3.Derive the Navier stroke equation of fluid mechanics.(M/J 2014)

Imagine   a closed control volume .0 within the flow field is moving through it. The control volume  occupies reasonably large ferrite region of the flow field .A control surface A0 is defined as the surface which bondsthe volume v0.
According to Reynolds transport theorem the rate of change of moments for asystem equals the sum of the rate of change of moments inside the control volume and the rate of efflux of momentum
Across the control surface.
The rate change of momentum for system is equal to the net external force acting on it   
    Rate of change of moments inside the control volume                                                               =   ddt  ᶴᶴᶴ ɐ  d ∀
= ᶴᶴᶴddt (ɐ  d ∀
Rate of efflux of  moments  through  control surface
      ᶴᶴA0  Pv(v.dA)=ᶴᶴA0  Pvv.ndA
   =ᶴᶴ0(v(.pv)+pv..v )d ∀
Surface force acting on the control volume
=ᶴᶴA0  dAσ
Body force acting on the control volume
=ᶴᶴ0   ρdd
Intially we got
ᶴᶴ0(ddt(ρv)+(v(.pv)+pv..v ) d∀

         =ᶴᶴ0(∇.σ+ ρd)d        
  ρ dvdt +vde       dt   +pv . ∇v+v(.pv)+pv..v)        =v.σ+ρ/b
we known that
=0 is the general from of mass conservation equation valid
for both compressible and in compressible flows.
  ρ (dvdt +v. pv)=∇.σ+ ρb
      ρ DvDt= ∇.σ+ ρb)
This equation is referred as Cauchy”& equation of motion .In this Equation,σ
is the stress tensor.
After having substituted σ  We get .
∇.σ= -∇p+(μ'+μ)∇(∇.∇)+μ2 v
from stnoke’s  hypothesis we get μ’+2/3 μ=0
Invoking above two relationship in to 1 we get
ρ DvDt= -∇p+μ2 v +1/3 μ∇(∇. v)+ρb
      This the most general from of navier –stokes equation

4.Derive the Stress transformations of fluid mechanics.

Consider the rectangular bar subject  to externally applied force that cause various mode of deformations which the bar .
Let p be a point within the structure .assume that a small cubical material element at point p with sides  parallel to the sides of the sides of the bar is cut out and analyzed .
The material is subjected to a combination of normal (σx ∆ σy)and shear (τxy)stress in xy plane
 Consider a second element at the same material point but with a different orientation than first element . Mechanical stress is symbolized with the Greek letter sigma and is defined as the force per unit area within a material ( = F/A). Mechanical stress is similarto the concept of pressure and has the same units (N/m2 and lbs/in2).

In the SI system one Newton per meter squared is one Pascal (Pa) of stress or pressure. Atmospheric gases that typically exert a pressure of 1 atm, 101.3 KPa (kilopascals), or 14.7 lbs/in2 on your body.

Note that mechanical stress is not vector quantity, but an even more complex quantity called a tensor.

Tensors are generalized vectors thathave multiple directions that must be accounted for, much like resolving a force into anatomically relevant axes like along a longitudinal axis and at right angles (shear).
The maximum force capacity of skeletal muscle is usually expressed as a maximum stress of about 25–40 N/cm2 or 36–57 lbs/in2.
This force potential per unit of cross-sectional area is the same across gender, with females tending to have about two-thirds of the muscular strength of males because they have about
two-thirds as much muscle mass a males.
One can assume that the second material element is obtained simply by rotating the first in the counter clockwise direction through an angle θ.
 Let x1 and y1 be two mutually  direction representing   the normal’s to the surface of the transformed material element .
The stress distribution on the transformation material element would be different than of the first .in general the second element may be subjected  to normal stresses (σx1 and σy1) and shear  stress (τx1y1)
As well .if stress σx, σy and τxy1 and the angle of rotation θ given ,the stress σx1 , σy1 and τx1y1 can be calculate using the following formulas

        σx1 =  σx+σy2   +  σx-σy2   cos(2θ)+  τxy sin(2θ)

        σy1 =  σy+σx2   +  σy-σx2   cos(2θ) -  τxy sin(2θ)  

       Τx1y1  =   - σx-σy2  sin (2θ) + τxy cos (2θ)
There equations can be used for transforming stress from one set of coordinates  (xy) another (x1 ,y1)

5.Derive the Strain energy function for fluid mechanics.

A material is said to be homogenous . when the distribution of the internal structure is such , that material point has same mechanical behavior. In heterogeneous material , the strain – energy function will additionally depend on the portion of the material point in the  reference placement X .
The measure of the deformation of a material created by a load is called strain. This deformation is usually expressed as a ratio of the normal or resting length (L0) of the material. Strain can be calculated as a change in length divided by normal length (L – L0)/ L0.

Imagine stretching a rubber band between two fingers. If the band is elongated to 1.5 times its original length, you could say the band experiences 0.5 or50% tensile strain. This text will discuss the typical strains in musculoskeletal tissues in percentage units. Most engineers use muchmore rigid materials and typically talk in terms of units of microstrain.

    For physical observation  we conclude that the strain energy increase monotonically with the deformation ,
          W(I)=0         and      w(F)0
           dw = Tij dij   = r(dI-da)
 w is the strain energy function , its derivation with respect to the strain is the stress .

6.Define Hooke’s law of elasticity.(M/J2013)

Hooke's law is a principle of physics that states that the force (F) needed to extend or compress a spring by some distance X scales linearly with respect to that distance.
            F = kX,
where k is a constant factor characteristic of the spring: its stiffness, and X is small compared to the total possible deformation of the spring.
    Soft tissues and cells exhibit several anelastic properties:
  • Hysteresis during loading & unloading of
  • Stress relaxation at constant strain
  • Creep at constant stress .
  • Strain rate dependence.
There properties can be modeled by theory of elasticity.
Visco elastic materials consists of polymers of variable chain length and filters resulting in to following stress strain diagram.

Slope of the major axis of the ellipse is a measure of material stiffness while the ratio of the minor stress strain relationship may be written as
a0   σ+i=1nai  +ditdti =b0 +j=1nbj djtdtj
o is stress and ϵ is the strain In this relation of all the coefficients a0………an and bo… are constants ,the material is referred to as linear elasticity.

     7.Write short note on newtanion and non newtanion fluid ?(N/D2013)
Constitutive Equations :
Two types of fluids:
1. Newtonian
2. non-. Newtonian fluids

Newtonian Fluid

Newtonian fluid's viscosity remains constant, no matter the amount of shear applied for a constant temperature.. These fluids have a linear relationship between viscosity and shear stress.
A Newtonian fluid Is a viscous fluid for which stress is proportional to the velocity gradient .(i.e time –rate of strain )
τ= μ du/dy

τ-sharestress exeted by the fluid
          du/dy-velocity  gradient perpendicular to the direction of shear.
 Non-. Newtonian fluids:
For a non- Newtonian fluids the viscosity change with the applied strain rate (velocity gradient ) As a result , non- Newtonian fluids may not have a well –defined  viscosity.

Non-Newtonian fluids are the opposite of Newtonian fluids. When shear is applied to non-Newtonian fluids, the viscosity of the fluid changes.
Constitute relation for Newtonian fluids

The stress ten son can be decomposed into spherical and deviation  parts

σ=τ-pI or   σij= τij-pʆij

Where p=-1/3   τ σ =-1/3 σij

Is the mechanical pressure and τ is stress deviator shear stress tensor )
Constitutive  relations for Newtonian fluid from three  elementary hypotheses.
  • τ should be linear function of velocity gradient.

  • This relationship should be isotropic as the physical properties of the fluid are assumed to show no preferred direction .
  • τ should vanish if the flow involves no deformation of fluid elements .


      σij= μ(μij+μji)-p ʆij
This is a relation for in compressible fluid (ie when ∇, μ=0)

8.What is viscoelasticity? Explain its types. (N/D2013)

Viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation. Viscous materials, like honey, resist shear flow and strain linearly with time when a stress is applied. Elastic materials strain when stretched and quickly return to their original state once the stress is removed.
Viscoelastic materials have elements of both of these properties and, as such, exhibit time-dependent strain. Whereas elasticity is usually the result of bond stretching along crystallographic planes in an ordered solid, viscosity is the result of the diffusion of atoms or molecules inside an amorphous material.
Viscoelasticity was further examined in the late twentieth century when synthetic polymers were engineered and used in a variety of applications.
Viscoelasticity calculations depend heavily on the viscosity variable, η. The inverse of η is also known as fluidity, φ. The value of either can be derived as a function of temperature or as a given value .
Depending on the change of strain rate versus stress inside a material the viscosity can be categorized as having a linear, non-linear, or plastic response. When a material exhibits a linear response it is categorized as a Newtonian material. In this case the stress is linearly proportional to the strain rate. If the material exhibits a non-linear response to the strain rate, it is categorized
A viscoelastic material has the following properties:
Types of Viscoelasticity
  • Linear viscoelasticity 
  • Nonlinear viscoelasticity 
Linear viscoelasticity is when the function is separable in both creep response and load. All linear viscoelastic models can be represented by a Volterra equationconnecting stress and strain:
Linear viscoelasticity is usually applicable only for small deformations.
Nonlinear viscoelasticity is when the function is not separable. It usually happens when the deformations are large or if the material changes its properties under deformations.

9.Write short note on  the Kinetics and  Kinematics of Motion ?(M/J 2014)

Kinetics is a term for the branch of classical mechanics that is concerned with the relationship between the motion of bodies and its causes, namely forces and torques. 
In Kinetics, velocities, accelerations and the forces which creates the motion.
 Kinematics is the branch of classical mechanics which describes the motion of points, bodies (objects) and systems of bodies (groups of objects) without consideration of the causes of motion.
In Kinematics,  velocities and accelerations without the forces/torques which creates the motion. Kinematics & Kinetics are bound by Newton’s second law,which stales that the external force (f) on an object is proportional to product of that object mass (m) and linear acceleration(a)           
for conditions of state equilibrium ,there are no external force because there is no accelerations are the sum of the external forces can be set equal to zero .however when an object is accelerating ,the so called inertial force must be consider and the sum of the force is no longer equal to zero .
ex :static and dynamic Equilibrium .
If this performed very slowly so that the acceleration is negligible static equilibrium conditions can be applied and the force required is 200n .However ,if this  same box is lifted with an accelerations  of 5m/s2 ,then the sum of force is not equal to zero and the force required is 300N .
       There is an analogous relationship for rotational motion ,in which the external moment (M) on an object proportional to that object moment of inertia (Z) and angular acceleration (α) 
                                            M=I α   
Just as mass is a measure of a reuse trance to linear acceleration moment of inertia is a measure of resistance to angular acceleration .It is affected both by
total mass an the distance that mass is from the COR .π as follows      
I=m π2
This is the kinetics and kinematics of motion.

10.Write short note on biomechanical principles and vector mechanics?

The lower the center of gravity the large the base of support the closer the line of gravity to the center of the base of support & the greater the mass the more stability increases.
Maximum effort
The production of maximum force requires the use of all the joint that can be used .(Ex foot ball player (kickers)
The production of maximum velocity requires the use of all the joints in order from largest to smallest.
(ex basket ball jump, short larger starts the motion & facter joint contributes)
Linear motion
The greater the applied impulse the greater the increase in velocity .Impulse =Force X time.
Movement usually occurs in the direction opposite that of the applied force.
Ex skiing, speed skating ,swimming.
Angular Motion :
Angular Motion is produced by the application of force acting at some distance from axis .(or a torque)
Angular movement is  constant when an athlete or object is free in the air.
Ex: diver rotates in air momenlium constant while in air .
Vector Mechanics:
Biomechanical parameters can be represented as either scalar or vector quantities .A scalar is simply represented by its magnitude .
Ex :mass ,time & length A vector is generally describe as both magnituted any orientation Ex :forces & moments.
The mostcommon use of vectors in biomechanics is to represent force such as muscle and joint reactions and resistance graphically with the use of line with an arrow at one end.
Vector addition :
    When study musculo skeletal biomechanics ,its common to have more then one force to consider .therefore it is important to understand how to work with more than one vector . when adding or subtracting  two vectors , there some important properties to consider.
vector addition is cumulative.
Vector addition is associative
Both magnitudes and direction on (orientation) vector must be taken into account .
It is called the principal of mechanics and vector mechanics.