bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of an Electro-Optic Scanner for Potential Endoscope Application
Authors: Wang W. , Lee S. , Jen A. , Reinhall P. , Nuckley D.
Published: July 2009

Technological advancements in endoscopy design are in current development due to the increased demand for minimally invasive medical procedures. One such advancement is reducing the overall size of the endoscope system while maintaining the resolution and field-of-view (FOV). Reduction of size results in less tissue damage and trauma during operation as well as faster recovery times for patients. Additionally, areas that are inaccessible by today's endoscope designs will be possible to examine. Current endoscopes use either a bundle of optical fibers (optical waveguides) and/or one or more cameras having an array of detectors to capture an image. Thus, the diameter of these devices employed for remote imaging cannot be reduced to smaller than the image size. Even if one ignores additional optical fibers used for illumination of a region of interest, the scope diameter is therefore limited by the individual pixel size of a camera or by the diameter of optical fibers used to acquire the image. Therefore, it is apparent to achieve scopes with less than 3 mm overall diameter using current technologies, resolution and/or FOV must be sacrificed by having fewer pixel elements. All commercially available scopes suffer from this fundamental tradeoff between high image quality and small size. More recently, our research has been working on developing a 2-D electro-optic scanner potentially be implemented for clinical endoscopic imaging application. The proposed optical device has several unique advantages. Electro-optical scanning offers a sensitive, facile, accurate, and superb quality method to capture images of physical and biological tissues. In addition, the minute physical size of the imaging system has a much needed advantage over conventional imaging systems. The proposed design is based on the fact that the propagation direction of a light beam can be changed when the index of refraction of an electro-optic medium is altered by the application of an external electric field. The basic design of the system consists of a thin film electro-optic polymer waveguide with built-in cascaded prisms structure for horizontal beam deflection and an electro-optic grating structure for vertical beam deflection. The cascaded prisms are combined with the electro-optic polymer to create a voltage-controlled horizontal beam deflection. A grating coupler, a structure that is commonly used as light coupling device for dielectric waveguide, is combined with the EO polymer to create the vertical controlled beam deflection. A collimated light beam coupled into the waveguide by a mechanical coupler via an optical fiber cascaded down these two deflection stages. When the beam exits, the emitted light beam is displaced along two orthogonal directions in a raster pattern. A photodetector array integrated in the same substrate captured the reflected intensity. The scanned imaged is then analyzed and reconstruct based on the received signal.
Creating Low-Impedance Coatings for Neural Recording Electrodes Using Electroplating Inhibitors
Authors: Ferguson J. E. , Boldt C. , Redish A. D.
Published: July 2009

Microelectrodes are routinely used for recording from ensembles of neurons for clinical and neuroscience research applications. The quality of the neural recording is highly dependant on the electrical properties of the microelectrode. Lowering the impedance of the electrode-electrolyte interface can improve the signal-to-noise ratio and the ability of the microelectrode to record from more distant neurons. Therefore, tetrodes, which are made by twisting four 12.7 μm nichrome wires together, are usually gold plated to lower impedances to 200–500 kΩ (measured at 1 kHz) before implantation. A further reduction in impedance could drastically improve recording quality but is not possible with standard gold electroplating methods without causing crossed connections (shorts) between the wires. Keefer et al. (2008, Nature Nanotechnology) reported that they could reduce electrode impedance and improve neural recordings by adding multi-walled carbon nanotubes to the gold plating solution, producing a “rice-like” texture on electrode coatings. We replicated this coating and were able to lower tetrode impedances to 120–150 kΩ without crossed connections. Furthermore, we found that by decreasing the electroplating current density and the concentration of multi-walled carbon nanotubes in the gold plating solution, we could create a 40–90 kΩ coating on each tetrode wire without any crossed connections. A scanning electron microscope (SEM) image revealed this 40–90 kΩ coating to be thick and globular with nano-scale texture, distinct from the “rice-like” coating of Keefer et al. The nano-scale texture coating had a large effective surface area likely responsible for the great reduction in impedance. In comparison, an SEM image of a standard gold-plated tetrode showed a thin coating with primarily lateral growth. The carbon nanotubes act as electroplating inhibitors by adsorbing onto the electrode surface and changing the dynamics of the gold electrocrystallization. We confirmed this by replacing the carbon nanotubes with polyethylene glycol (PEG), a known electroplating inhibitor, recreating the nano-scale texture and 40–90 kΩ tetrode impedances. By varying the concentration of electroplating inhibitors and the electroplating current, the dynamics of gold electrocrystallization can be controlled. This gives the ability to design an electrode coating with a specific shape, thickness, and texture that can be tailored to a specific application. Creating a low-impedance coating with a nano-scale texture using electroplating inhibitors can improve the recording quality of microelectrodes and can allow for the use of smaller microelectrodes that were previously limited by their high impedance. Supported by a grant from the Institute for Engineering in Medicine (U Minnesota) and training grant support from T32-EB008389. Corresponding author; email: redish@umn.edu
A Wireless, Passive pH Sensor Based on Magnetic Higher-Order Harmonic Fields
Authors: Horton B. , Tan E. , Pereles B. , Ong K.
Published: July 2009

A wireless, passive sensor was fabricated for remote monitoring of chemical analytes in the human body. The sensor was made of a magnetically soft film (sensing element) and a permanent magnetic film (biasing element) sandwiching a reversibly swelling hydrogel. When subjected to a low frequency magnetic AC field, the sensing element generated higher-order harmonic magnetic fields that were detected with a remotely located detection coil. In the presence of a DC magnetic field (biasing field), such as that generated from the biasing element, the pattern of the higher-order harmonic magnetic fields varied, and the magnitude of change (referred to as the harmonic field shift) was proportional to the strength of the biasing field. The hydrogel, which acted as a transducer that converted variations in the chemical concentration into changes in dimensions, physically varied the separation distance between the sensing and the biasing elements. This causes a change in the magnitude of biasing field experienced by the sensing element, thus changing its higher-order harmonic field shift allowing remote measurement of chemical concentrations. The novelty of this sensor was its wireless and passive nature, which allows it to be used inside a human body for long term chemical monitoring. A scaled-up prototype was fabricated and tested to demonstrate the pH monitoring capability of the sensor. The main structure of the prototype sensor was a polycarbonate substrate containing a larger rectangular well of 36mm×8mm×4mm on top of a smaller well of 30mm×5mm×2mm (see Fig. 1). The smaller well was filled with hydrogel made of (poly)vinyl alcohol and (poly)acrylic acid. A commercial magnetoelastic thick film, Metglas 2826MB from Metglas Inc., was attached to the step at the bottom of the larger well and allowed to rest on the hydrogel. The DC magnetic field was provided by an Arnokrome III film (Arnold Magnetic Technologies) of 30mm×6mm attached at the bottom of the sensor structure. The sensor was placed on the detection coil, and its response was measured with a spectrum analyzer while exposed to test solutions of varying pH. The sensor's harmonic field shift, when cycled between pH 7 and pH 3, was measured and plotted in Fig. 2. As shown in the figure, the hydrogel swelled when the sensor was exposed to pH 3, decreasing the harmonic field shift. The response and recovery times of the hydrogel were below 2 minutes. This experiment proves the feasibility of the technology for real-time, remote monitoring of pH. Further work includes improving the response time and sensitivity of the hydrogel, as well as miniaturization of the sensor.
KTP High Power Laser-Tissue Interactions: In Vitro Experiment and Simulation
Authors: Elkhalil Hossam , Akkin Taner , Barocas Victor H. , Bischof John C.
Published: July 2009

Benign prostatic hyperplasia (BPH) is one of the most common disorders and the most common cause of lower urinary tract symptoms (LUTS) in elderly men. Transurethral resection of the prostate (TURP) is considered the gold standard treatment for BPH; however, laser prostatectomy has several advantages over TURP with regard to reduced catheterization and morbidity particularly in high-risk patients. Of the many lasers that can be used in the laser prostatectomy, the GreenLight potassium-titanyl-phosphate (KTP) laser is one of the most commonly used. The optimum outcome of this laser procedure is ablation with minimal coagulation. Our objective was to experimentally and theoretically characterize the KTP laser-tissue interactions in order to understand the laser and tissue parameters that lead to an optimal outcome. The rat hind limb muscle was used as a model for the in vitro study. Q-switched 532 nm laser (GreenLight PV, American Medical Systems, MN) was used and the laser was allowed to scan over the tissue with controlled speed and working distance, distance from the tip of the optical fiber to the tissue's surface. Injury was assessed by digital images of the tissue's cross section in terms of ablation, zone of removed tissue, and coagulation, zone of thermally denatured protein, zones. Ablation simulation was done in Matlab R2008a and the ablation was assumed to be a vaporization process. Thermal properties of water were assumed for the basic first run, where the ablation energy of tissue was assumed to be the vaporization energy of water. Parametric study involving changing the ablation energy, thermal conductivity, and absorption (attenuation) coefficient of tissue was performed. Ablated tissue volume increased with decreased scanning speed and trended to saturate at higher values of working distance and lower scanning speed. The optimal therapeutic outcome (minimal coagulation volume and maximal ablation volume) was achieved at 0 mm working distance and 1 mm/s scanning speed. The simulation was able to capture and predict the effect of the tested parameters (ablation energy, thermal conductivity, and absorption coefficient) on the therapeutic outcome. Notably, decreased ablation energy and thermal conductivity, and increased absorption coefficient were predicted to enhance the KTP laser ablation therapeutic outcome (i.e., reduce coagulation volume and increase ablation volume). This will open avenues to improve KTP laser prostatectomy by modulating optical, thermal, and mechanical properties of prostatic tissue.
Cardiac Arrest Alert System
Authors: Schroeder M. , Alvarez E. , Steele M. , Malhotra P. , Mbipeh M.
Published: July 2009

According to the American Heart Association, approximately 166,200 out-of-hospital cardiac arrests occur each year. It is estimated that a victim's chances of survival are reduced by 7-10 percent for every minute that passes without treatment. Obviously, time is very critical in such situations. In most cardiac arrest cases, there is little to no warning to the victim that their heart has stopped and thus no time to notify others that emergency care is immediately required. To help alert the victim and others that a cardiac arrest episode has occurred, an ambulatory alarm and notification system has been built for individuals at high risk of cardiac arrest. The cardiac arrest alert system uses a ring-style photoplethysmograph that is connected to an armband unit which performs signal processing and wireless transmission and possesses an audible alarm. A wristband interface provides visual and tactile warnings, a reset button and a threshold adjuster. If the user's heart rate goes outside the preset range or is not detected by the system, a visual and tactile warning notifies the user of the situation. If the device is not reset or the problem not rectified within several seconds, the device then goes into full activation mode and sounds a loud alarm to notify nearby individuals who may be able to provide emergency assistance to the user. In full activation mode, the device also wirelessly transmits a signal to a central unit that, when signaled, automatically calls 911 and plays a pre-recorded message that states the incident and specifies the location. An additional phone number can also be stored so that another notification call is automatically performed. The central unit has a speaker so that the notification message is locally audible as well. In emergency situations, the cardiac arrest alert system will provide a life-saving service by rapidly alerting the user as well as nearby individuals and emergency respondents who can provide immediate assistance.
Visualization of Coronary Artery Bypass Grafts and Coronary Artery Stents in Re-Animated and Perfusion Fixed Human Hearts
Authors: Bateman M. G. , Rolfes C. D. , Iaizzo P. A.
Published: July 2009

Using Visible Heart® methodologies we imaged coronary artery bypass grafts (CABGs) and coronary stents in isolated beating human hearts and perfusion fixed human hearts. Due to the varying cardiac health of the donor hearts it has been possible to see progressive levels of stent endothelialization and vascular calcification. The isolated heart model uses a clear Krebs–Henseleit buffer in place of blood, allowing for the unique opportunity to image the coronary vessels. In the isolated human heart a fiberscope was inserted into either the native coronary artery or the CABG with the heart in sinus rhythm. In order to verify cardiac function during the imaging process the following measurements were read at a sampling rate of 5 kHz: ECG, aortic flow, and ventricular pressures. Perfusion fixed hearts were fixed in an end diastolic state achieved by applying pressures comparable to physiological conditions. This process causes the coronary arteries to fix in a dilated state. CABGs of human hearts were then imaged using fluoroscopy (angiograms) and fiberscopic techniques. The stented native coronary arteries of human hearts were imaged via fluoroscopy and by dissection. Through a variety of imaging techniques and using Visible Heart® methodologies we have obtained a unique visualization of a CABG and a coronary artery stent in a beating human heart during sinus rhythm. Investigative studies in perfusion fixed human hearts have provided a more complete anatomical imaging study of stent endothelialization in the native coronary arteries and vascular calcification in bypass grafts.
A Laser-Based Device for Tissue Fusion
Authors: Larson M. C.
Published: July 2009

A prototype device (patent pending) has been created, and successfully used, to fuse tissue membranes as an alternative to sutures or staples. The joining, or coaptation, is accomplished through the controlled application of laser heating and pressure to induce protein denaturation and subsequent tissue fusion, through renaturation and intertwining, across the interface. Lasers have been used by a number of researchers to close wounds in controlled laboratory tests over the last 15 years. Many encouraging results have been obtained; however, no commercial delivery systems are currently available. This is due primarily to two factors: requiring an inordinate amount of experience on the part of the operator to detect changes in tissue appearance, and attempting to achieve general applicability for multiple tissue systems, i.e., a one-size-fits-all approach. Different combinations of system performance parameters may be required for different types of tissues. The present device overcomes these barriers as it is tailored for the particular application of septal laser fusion, namely for the coaptation of mucoperichondrial membranes. The optimal laser performance characteristics are pre-set for nasal tissue and packaged in an easy to use device. The important parameters involved in fusing biological tissues using radiation from laser sources are identified. The development of the device followed from computational modeling of the fusion process based on engineering first-principles from heat transfer, fluid dynamics and optics, and from experimental results on a particular tissue system. The experiments were designed and analyzed using orthogonal arrays, employing a subset of the relevant parameters, i.e., laser irradiance, dwell time and spot size, for a range of wavelengths. The in vitro fusion experiments employed 1 cm by 1 cm sections of equine nasal mucosa having a nominal thickness of 1 mm.
Design of Ultrasonic Motion Analysis System for Estimating Segment's Stabilization During Dynamic Condition
Authors: Hemmati N.
Published: July 2009

While the function of central and peripheral nervous system decreases (caused by aging, vestibular deficiency or stroke), maintaining of body stability become hard. Studies indicate that movement coordination of axial segments (head, thorax, and pelvis) in a dynamic state such as walking disrupted in these pathologic conditions. In recent years goniometry and cinematography have been widely used to measure active or passive range of motion (ROM) in asymptomatic adults. The aim of this investigation is to design and implement a new method by evidence based approach for estimating the level of impairment in segment stability and improvement after treatment by measuring quality or quantity of movement among axial segments. Ultrasound based coordinate measuring system (CMS) can continuously measure motion in three dimensions during the course of time in a dynamic condition. The measuring procedure is based on the travel time measurement of ultrasonic pulses that are emitted by miniature transmitters (markers) to three microphones built into the compact device. Our system consist electronic, mechanic and software sections. Electronic board include: 40 KHz pulse oscillator, PRF pulse generator, sensor drivers, high voltage analog switches, 60 dB Amplifier, signal detector and CPU. Transmitter sensors which have been mounted on body send ultrasonic burst signals periodically and other 3 sensors which arranged on a T-shape Mechanical base receive the 3 dimensional coordinate of these transmitters. After sending 3D coordination data to PC via serial port, a complex and elaborative Visual Basic software calculate the angular dispersion, angular rate acceleration for each also calculate the stabilization parameters among segments such as Al (anchoring index) and cross-correlating between head and trunk coordinates.
Harmonic Focus Case Study: Leading Innovation Through Unique User Research Methods and Tools
Authors: Morgan Stuart , Wilcox Stephen
Published: July 2009

Ethicon Endo-Surgery's Harmonic FOCUS is a curved-shear (blade with clamp arm) surgical instrument that combines the intuitive elements of a classic precision instrument with a Harmonic ultrasonic hand piece for a revolutionary multifunction precision device. We propose to describe the unique approach to user research used in the development of the product and how the team used these innovative methods and tools to identify and meet the following design and engineering challenges: 1. Combine the surgical tasks of dissecting, grasping and simultaneously cutting and coagulating into one precision device for the first time. The Harmonic FOCUS was developed as a result of three years of extensive market assessment and a unique research methodology, including a novel process of ethnographically observing and graphically mapping thyroidectomy procedures. 2. Miniaturize the hand piece (transducer) from the existing ultrasonic product line while retaining its clinical performance (speed and hemostasis). The following dramatic and extensive design changes offer improved clinical performance: Reducing the volumetric size of the transducer 55% relative to the predecessor device. Achieving reliable control of clamp force. Curving the blade to resemble typical surgical instruments. Improving speed of operation. Reduction of residual heat. 3. Provide the surgeon with superior and intuitive ergonomics by leveraging elements of a classic precision tool. The team combined the essential elements of a classic precision tool with Harmonic (ultrasonic) technology to develop a revolutionary, multifunctional device with superior and intuitive ergonomics. Surgeons concur with the versatile, comfortable design. 4. Use materials that are all sterilization-compatible. Extensive research was done to identify and use materials that were all compatible with ethylene oxide sterilization. The device is packaged in flexible packaging and ethylene-oxide sterilized prior to sale. Harmonic FOCUS is designed for single-patient use. The Harmonic Blue Hand Piece is sold non-sterile and is qualified for multiple sterilization methods readily available in hospitals. The hand piece can be reused up to 100 times.
Distance Measuring Device Over Body Surface
Authors: Tiryaki E. , Singh V. , Tewfik A. H.
Published: July 2009

Nerve conduction studies help to diagnose muscle and nerve diseases and point to the underlying cause and potential treatments. Conduction studies involve stimulating nerve at different points along its course and recording the response with an electrode, conduction velocity is determined by dividing the distance traveled by the time it takes the impulse to travel that distance. While the measurement of time is done electronically and is very accurate, measurement of distance in every commercial laboratory is done by marking the skin and measuring the distance with a flexible tape measure. Such distance measurement is highly error prone and leads to erroneous results and misdiagnosis. We present a device to measure distances along the body surface. It eliminates examiner error in the measurement of distance. It delivers an operator-independent and reproducible measurement and thereby increases accuracy of test results and avoids misdiagnosis. Furthermore, the device saves a significant amount of time. Stopping to pull out a tape measure, reading it and entering the data into the computer, all adds time to the length of the procedure. The measurement device eliminates these steps thereby increasing efficiency. It also transmits the measured distances directly to the computer, thus eliminating error in data entry. The device uses the established optical mouse technology at its core. It can measure displacements with a 0.0635 mm resolution. It is based on a commercial chip set, ADNS-5030 from ‘Avago Technologies.’ The system consists of an optoelectronic sensor which measures changes in position by optically acquiring sequential skin surface images (frames) and mathematically determining the direction and magnitude of movement. The sensor only needs to be pointing at but not touching the skin. The main advantage of this approach is that it is contactless, eliminating the need for disinfection. Although, current limitation of the device is in measuring accurately over non-planar surface due to its considerably large size making it difficult to maneuver over bumpy surfaces. Initial results for measurement studies performed over a diverse subject pool (in terms of skin color, hair density) results are promising with an error less than 9% for distances over 75 mm. A reduction in size of the device would lead to more accurate results as smaller size would help in easy maneuverability. Future implementations will exploit the contactless feature and integrate the measurement in the stimulus probe, reducing testing time and the need to operate multiple devices.
Development of a Fiberoptic Distributive Shear/Pressure Sensor
Authors: Wang W. , Soetanto W. , Reinhall P. , Ledoux W. , Nuckley D.
Published: July 2009

An estimate of $6 billion is being spent annually to deal with diabetes-related health problems. In the United States, 6% of the population (about 18 million people) has diabetes, either diagnosed or undiagnosed. During their lifetimes, about 15% of diabetic patients will develop a foot ulcer. More than 60,000 of them will end up with amputations of lower extremities due to complications arising from diabetes mellitus, accounting for nearly two-thirds of the total number of nontraumatic amputations performed annually. Previous studies report that has indicated that both the vertical and shear components of ground reaction force play a role in the formation of plantar ulcers. However, the exact relationship between stresses and ulcer formation is still unclear. The reason for that is due to lack of a sensor that is currently available to be able to measure pressure and shear force on the plantar surface simultaneously. It is because of these inadequacies that have motivated the search for a new design to transduce pressure and shear stress based on a multi-layered optical bend loss sensor. We have recently developed a sensor that can be used to measure shear and pressure of an extended area using fiber optic technology. The fiber optic technique that we have developed has also been extended by utilizing an array of microfabricated waveguides made of polydimethylsiloxane (PDMS). For the fiberoptic technique, the pressure/shear sensor consisted of an array of optical fibers lying in perpendicular rows and columns separated by elastomeric pads. A map of pressure and shear stress was constructed based on observed macro bending through the intensity attenuation from the physical deformation of two adjacent perpendicular fibers. Each sensing layer consists of multiple fibers molded into a thin PDMS substrate. In this design, the top layer is composed of a 3 by 3 fiber mesh with 9 intersection points and the bottom layer is made of a 4 by 4 fiber mesh with 16 intersection points. The space between the adjacent fibers is 0.5 cm. The pressured points between the top and the bottom layer are offset by 0.25 cm which is used to increase the shear sensitivity. In the experiment, the sensor was tested with various loading condition. A force image algorithm using neural networks was developed to identify the loading pattern, magnitude and direction of loads that were applied at more than one pressure point. Here 3 loading patterns with 5 different loading directions and 3 different loading magnitudes were tested. The results show a >90% accuracy was obtained using an algorithm with 2 layered neural networks system.
Experimental Evidence of Hydroacoustic Pressure Waves in a Francis Turbine Elbow Draft Tube for Low Discharge Conditions
Authors: Arpe Jorge , Nicolet Christophe , Avellan François
Published: July 2009

The complex three-dimensional unsteady flow developing in the draft tube of a Francis turbine is responsible for pressure fluctuations, which could prevent the whole hydropower plant from operating safely. Indeed, the Francis draft tube is subjected to inlet swirling flow, divergent cross section, and the change of flow direction. As a result, in low discharge off-design operating conditions, a cavitation helical vortex, so-called the vortex rope develops in the draft tube and induces pressure fluctuations in the range of 0.2–0.4 times the runner frequency. This paper presents the extensive unsteady wall pressure measurements performed in the elbow draft tube of a high specific speed Francis turbine scale model at low discharge and at usual plant value of the Thoma cavitation number. The investigation is undertaken for operating conditions corresponding to low discharge, i.e., 0.65–0.85 times the design discharge, which exhibits pressure fluctuations at surprisingly high frequency value, between 2 and 4 times the runner rotation frequency. The pressure fluctuation measurements performed with 104 pressure transducers distributed on the draft tube wall, make apparent in the whole draft tube a fundamental frequency value at 2.5 times the runner frequency. Moreover, the modulations between this frequency with the vortex rope precession frequency are pointed out. The phase shift analysis performed for 2.5 times the runner frequency enables the identification of a pressure wave propagation phenomenon and indicates the location of the corresponding pressure fluctuation excitation source in the elbow; hydroacoustic waves propagate from this source both upstream and downstream the draft tube.
Impact of Orifice Length/Diameter Ratio on 90 deg Sharp-Edge Orifice Flow With Manifold Passage Cross Flow
Authors: Nurick W. H. , Ohanian T. , Talley D. G. , Strakey P. A.
Published: July 2009

The available information describing the various stages of flow conditions that occur as the flow transitions from noncavitation to cavitation (turbulent flow), supercavitation, and finally separation in sharp-edge 90 deg orifices is extensive. However, although sharp-edge orifices in cross flow represent a significant number of injection schemes inherent in many applications, data for this configuration are sparse or nonexistent. This study is intended to increase the database and understanding of the driving variables affecting the flow in all of these conditions. Tests were carried out in a unique test facility capable of achieving large variations in back pressure, flowrate, and operating upstream pressure. The configuration and test ranges of this study includes orifice length/diameter ratios from 2 to 10, upstream pressures from 7.03 kg/cm2 to 105.1 kg/cm2, orifice/manifold area ratio of 0.028 to 0.082, and manifold cross flow velocity of from 410 cm/s to 1830 cm/s. The results for these small area ratio configurations support two different first order models, one for cavitation and the other noncavitation both in turbulent flow. Under cavitation conditions the discharge coefficient is related to the contraction coefficient and the cavitation parameter to the 1/2 power. In the noncavitation flow regime the head loss is related to the loss coefficient and the dynamic pressure at the orifice exit. Both the head loss and contraction coefficient were found to be a strong function of the ratio of manifold/orifice exit velocity. Equations are provided defining the relationships that allow determination of the contraction coefficient, discharge coefficient, and head loss between the contraction coefficient, as well as the loss coefficient and operating conditions. Cavitation parameter values for cavitation inception, cavitation, and supercavitation are also provided. The potential flow theory was shown to predict the contraction coefficient when upstream (manifold to vena-contracta) losses are minimal.
Simulation of Train Derailment in Passing Over Rails With Random Irregularities on a Viscoelastic Foundation
Authors: Durali Mohammad , Jalili Mohammad Mahdi
Published: July 2009

Derailment of a passenger wagon on a rail with random irregularities is investigated in this paper. The wagon having 48 degrees of freedom is assumed to travel over a rail on a viscoelastic foundation. The wagon model is a 3-D, non-linear model of a passenger train car, considering non-linear elements for the primary and secondary suspension systems having friction and slack between their elements, the center pivot with kinematics constraints, forces between pads, and bolster. The motion of the wagon on rail with random vertical irregularities is simulated for different line grades and travel speeds. Derailment coefficient and a new derailment criterion are used to investigate probability of wheelset derailment moving on different line grades. The study shows that the new criterion can very well predict wheelset derailment and can duplicate the predictions by conventional derailment coefficient (Q/P). Comparison of the wagon derailment on lines with different sleeper rigidity shows that increase in sleeper rigidity decrease derailment probability.
An Approach for the Modularization of a Product Architecture of Redesign Processes of Complex Systems
Authors: Albers Albert , Sedchaicharn Korkiat , Sauter Christian , Burger Wolfgang
Published: July 2009

Design Structure Matrix (DSM) is known as an efficient tool to modularize product architectures. It is only effective when all the matrix elements are described with a similar level of abstraction. This lies generally in the level of the real existing components. In order to implement a DSM, all assemblies, components and their relations have to be defined beforehand. In this step, the product architecture is often developed intuitively without any analysis. After the analysis using DSM, the developed product architecture normally requires rectification. Some components have to be designed and modified repeatedly. In this paper, the model for describing the relationship between function and embodiment, the Contact and Channel Model (C&CM) as well as an approach and its implementation will be presented to avoid this repetition. After a principle solution has been selected, the system is modeled with C&CM elements in a new intermediate level of abstraction. An integration analysis by DSM can be performed in parallel with the use of a search algorithm to find the modular product architecture. The analysis result is a guideline for a modular architecture which helps designers to reduce the number of required iterations. This approach is implemented in the development of a robot forearm for the humanoid robot ARMAR III.
A Systematic Approach to Support Drive Train Design Using Tools for Human Comfort Evaluation and Customer Classification
Authors: Albers Albert , Lerspalungsanti Sarawut , Du¨ser Tobias , Ott Sascha , Wang Jiangang
Published: July 2009

This article presents a systematic procedure and Artificial Neural Networks (ANN) based tool for comfort objectification and customer classification, to support drive train developer during the product development process. In this case, the term “comfort objectification” can be clarified as reproduction of subjectively sensed convenience of a passenger through objectively measurable values. Many factors, such as noise, vibration, physical or psychological condition of a passenger generally influence the ride comfort. The main purpose of this project is to develop the drive train and his assemblies which can sustain customers’ demand of vibration comfort. The presented methods enable the identification and the evaluation of vehicle dynamic properties from the passengers’ point of view during start-up, shifting, steering as well as other procedures in the early stage of the product development process. For instance, this tool is developed for the evaluation of ride comfort during a start-up of a front-drive, intermediate-class car. To estimate the subjective sensation, the new driver modeling tool based on ANN is developed from the way individual drivers make their assessment. This paper presents a user-friendly interface which allows both experts and users who are still short of experience in the ANN field, to create different network structures depending on the task. By means of this tool, the modeling process can be effectively simplified and shortened. As a result, the objective values captured during each drive test are efficiently correlated with the subjective sensation. Consequently, the high performance of comfort prediction can be achieved. By using self organizing map as a tool for driver classification, the different types of drivers can be considered due to their comfort expectation and style of driving. The comfort prediction concerning each driver group can then be carried out. According to the approach of virtual drive train development, in this study, the elaborated multi-body simulation models are primarily used to generate several virtual start-up processes. This enables the determination of NVH properties of the future product and allows the developer to investigate the effect of vibration like judder and jerking on the degree of ride comfort. By applying objective data from the simulation, the comfort assessment using the presented tools can be executed. In the long run, costly drive tests and cost-intensive prototypes can be partially replaced.
Determination of the Instantaneous Pole Axes in Single-DOF Spherical Mechanisms
Authors: Di Gregorio Raffaele
Published: July 2009

In spherical mechanisms, the instantaneous pole axes play the same role as the instant centers in planar mechanisms. Notwithstanding this, they are not fully exploited to study the kinematic behavior of spherical mechanisms as the instant centers are for planar mechanisms. The first step to make their use possible and friendly is the availability of efficient techniques to determine them. This paper presents a general method to determine the instantaneous pole axes in single-dof spherical mechanisms as a function of the mechanism configuration. The presented method is directly deduced from a algorithm already proposed by the author for the determination of the instant centers in single-dof planar mechanisms.
Evaluation of Vertical Wall-To-Guardrail Transition
Authors: Atahan Ali O. , Bonin Guido , El-Gindy Moustafa
Published: July 2009

Transition barriers are used to connect longitudinal barriers that have different stiffnesses. They are designed to provide a gradual increase in stiffness towards the stiffer barrier section. In this study, a W-beam rail and a W-beam rubrail transition connecting a rigid bridge rail to a semi-rigid guardrail was evaluated using numerical and experimental methods. First, a finite element model of the transition design was constructed and validated using a 2000 kg pickup truck impact. Then, a series of vehicle models, i.e., 900 kg compact automobile, 8000 kg single unit truck and finally 30,000 kg heavy truck was used to evaluate the impact performance of the same transition design numerically. Simulation results predict that the double W-beam transition barrier performs acceptably in containing and redirecting all vehicles except 30,000 kg heavy truck. Occupant injury criteria were also found to be acceptable for all the cases, except 30,000 kg truck impact. Performing further simulations with vehicle sizes heavier than 8,000 kg that exist in crash testing guidelines is recommended to evaluate the acceptability limit of existing W-beam rail and a W-beam rubrail transition.
Topology Optimization for Steady-State Heat Transfer Problems Including Design-Dependent Effects
Authors: Iga Atsuro , Nishiwaki Shinji , Izui Kazuhiro , Yoshimura Masataka
Published: July 2009

In this paper, a topology optimization method is constructed for thermal problems with generic heat transfer boundaries in a fixed design domain that includes design-dependent effects. First, the topology optimization method for thermal problems is briefly explained using a homogenization method for the relaxation of the design domain, where a continuous material distribution is assumed, to suppress numerical instabilities and checkerboards. Next, a method is developed for handling heat transfer boundaries between material and void regions that appear in the fixed design domain and move during the optimization process, using the Heaviside function as a function of node-based material density to extract the boundaries of the target structure being optimized so that the heat transfer boundary conditions can be set. Shape dependencies concerning heat transfer coefficients are also considered in the topology optimization scheme. The optimization problem is formulated using the concept of total potential energy and an optimization algorithm is constructed using the Finite Element Method and Sequential Linear Programming. Finally, several numerical examples are presented to confirm the usefulness of the proposed method.
Topology Optimization of Multiple Parts in Dynamic Controlled Systems
Authors: Albers Albert , Ottnad Jens , Ha¨ußler Pascal , Minx Johannes
Published: July 2009

The importance of computer aided engineering (CAE) in product development processes and research has been increasing throughout the past years. Consequently, optimization tools gained more and more importance. In state-of-the-art processes and methods concerning structural optimization it is assumed that there exists a set of external loads or load functions acting on the part. Very often modern products represent complex mechatronic system. The fact that the system’s dynamic properties and its overall behaviour may change due to geometric modifications of a part caused by an optimization process is typically neglected. In order to take into account the interaction between the part, dynamic system, control system and the changing mechanical behaviour with all its consequences for the optimization process, a simulation of the complete mechatronic system is integrated into the optimization process within the research work presented in this paper. A hybrid multibody system (MBS) simulation, that is, a MBS containing flexible bodies, in conjunction with a cosimulation of the control system represented by tools of the Computer Aided Control Engineering (CACE) is integrated into the optimization process. The research work presented in this paper is a contribution towards the integration of existing CAE methods into a continuous process for structural optimization. The benefits will be illustrated by an example, namely a part of the humanoid robot ARMAR III of the collaborative research centre for “Humanoid Robots” [1]. Especially the optimization of two parts at a time within one optimization loop allows an efficient optimization of structures “within” their surrounding mechatronic system.
Mathematical Formulation of Macroscopic Feature for Digital Style Design
Authors: Kawanishi Shouki , Matsunaga Emi , Ujiie Yoshiki , Matsuoka Yoshiyuki
Published: July 2009

In style design, a mathematical formulation of a macroscopic feature, which emerges from the sum of the shape elements, is important. However, mathematically formulating a macroscopic feature is difficult using conventional microscopic shape information such as dimension and curvature. Because the evaluation of a macroscopic feature depends on the experience of the designer, constructing a mathematical model to formulate the macroscopic feature is highly desired. Herein, we examined the mathematical formulation of the macroscopic feature “complexity”, which affects the evaluation of important aspects in styling, such as “beauty” and “similarity.” We report the guideline with regard to circumstance and cognition experiments to mathematically formulate the macroscopic feature “complexity.”
Using Enviromental Models Approximated by Fuzzy Identification for Hybrid Planning of Mechatronic Systems
Authors: Schmidt Alexander , Adelt Philipp , Esau Natascha , Kleinjohann Lisa , Kleinjohann Bernd
Published: July 2009

Above the controller level a lot of components are needed in mechatronic systems for the development towards self-optimizing systems. One of these components is a hybrid planning architecture. This architecture integrating discrete and continuous domains is of major importance to support the permanent determination of system objectives and their implementation during the course of action. Through this the principle of self-optimizing mechatronic systems is defined as well. Such a novel hybrid planning architecture is outlined in this paper. In order to plan efficiently and safely, environment models are needed for predicting future system behaviors. In this paper we propose a fuzzy logic based approach to environment modeling and apply it in a railway-bound domain within the context of an air gap adjustment system for a dual-fed linear motor powering a wheeled train.
Knowledge-Based Repository to Support Engineering Design
Authors: Crowder Richard M. , Wong Sylvia , Shadbolt Nigel , Wills Gary
Published: July 2009

Manufacturers are currently shifting their focus from selling products to providing services, hence the product’s designers must increasingly consider life-cycle requirements, in addition to conventional design parameters. To identify possible areas of concern, engineers must consider knowledge gained through the life cycle of similar or related product. However, because of the size and distributed nature of a company’s operation, engineers often do not have access to front-line maintenance data. In addition, the large number of documents generated during the design and operation of a product makes it impractical to manually review all documents thoroughly during a task. This paper presents a knowledge-based document repository demonstrator that is capable of providing such support for the maintainers and designers of jet engines.
An Efficient Re-Analysis Methodology for Probabilistic Vibration of Large-Scale Structures
Authors: Zhang Geng , Nikolaidis Efstratios , Mourelatos Zissimos P.
Published: July 2009

It is challenging to perform probabilistic analysis and design of large-scale structures because it requires repeated finite-element analyses of large models and each analysis is expensive. This paper presents a methodology for probabilistic analysis and reliability-based design optimization of large-scale structures that consists of two re-analysis methods; one for estimating the deterministic vibratory response and another for estimating the probability of the response exceeding a certain level. Deterministic re-analysis can analyze efficiently large-scale finite element models consisting of tens or hundreds of thousand degrees of freedom and large numbers of design variables that vary in a wide range. Probabilistic re-analysis calculates very efficiently the system reliability for different probability distributions of the design variables by performing a single Monte Carlo simulation. The methodology is demonstrated on probabilistic vibration analysis and a reliability-based design optimization of a realistic vehicle model. It is shown that computational cost of the proposed reanalysis method for a single reliability analysis is about 1/20th of the cost of the same analysis using NASTRAN. Moreover, the probabilistic re-analysis approach enables a designer to perform reliability-based design optimization of the vehicle at a cost almost equal to that of a single reliability analysis. Without using the probabilistic re-analysis approach, it would be impractical to perform reliability-based design optimization of the vehicle.
Design and Dynamic Simulation of a Novel Piano Action Mechanism
Authors: Nelson Carl A.
Published: July 2009

A novel piano action mechanism is presented, which is based on a multi-lobed lifting cam. The cam replaces several bodies in the standard action mechanism and allows the upright piano to achieve fast repetition of a single note, which is a quality more commonly attributed to grand piano actions. The use of simulation software to aid in tuning of the design is described, and the final simulation results are presented. These results indicate the ability of the new mechanism to achieve good performance over a range of playing intensities and to play repeated notes in rapid succession.