bluuebunny/crossref_metadata_2025 huggingface dataset:
The Biogeomorphology of Mangroves and Their Role in Natural Hazards Mitigation
Authors: Ostling Johanna L. , Butler David R. , Dixon Richard W.
Published: July 2009

Along low‐relief coasts in tropical regions, mangroves occupy the biogeographical landscape usually occupied by salt‐marsh or cypress ecosystems in more temperate regions. Over 50 species of mangroves are found worldwide. In tropical regions, mangroves are the prevalent coastal wetland ecosystem, overshadowed in the public mind by tropical rainforests and coral reefs. Mangroves exist on the tropical rims of all continents except Antarctica. Numerous species of mangroves exist; collectively they create large ecosystems such as the Sundarbans in Bangladesh and India that provide habitats for endangered species, including the Bengal Tiger. As biogeomorphological agents, mangroves interact with tidal flows to entrap and stabilize sediment, create humus, and alter tropical coastal environments. Mangrove sediments and pollen entrapped therein record substantial sea‐level rises and falls during the Holocene, including a mid‐Holocene highstand, and a regression associated with the Little Ice Age. Mangroves provide habitats for a variety of coastal creatures, including crabs, juvenile fish, and sponges. Worldwide, the mangrove ecosystem is threatened by anthropogenic activities such as aquaculture, urban development, and forestry. Removal of mangroves not only endangers sensitive ecosystems, but also reduces the protection from natural hazards that mangroves offer. Tsunami and storm surges from tropical cyclones are dissipated by the intertwined root systems of the mangroves, limiting the destructive potential of the surging water, although the extent of protection offered by mangroves is controversial. The natural protection of the mangroves has proven superior to man‐made objects to deflect tsunami and storm surge. Mangrove revegetation efforts are underway in numerous countries, most notably Bangladesh, Vietnam, Thailand, and Tanzania. A variety of remote‐sensing platforms provide the ability to monitor mangrove recovery or decline around the world. The ultimate results of anthropogenic influences on mangroves remain to be seen.
MicroRNA expression profile in non‐cancerous colonic tissue associated with lymph node metastasis of colon cancer
Authors: HUANG Zhi Ming , YANG Ji , SHEN Xiao Ying , ZHANG Xiao Yan , MENG Fan Sheng , XU Jiang Tao , ZHANG Bao Feng , GAO Heng Jun
Published: July 2009

OBJECTIVE:  To identify microRNA expression patterns associated with the lymph node metastasis of colon cancer.

METHODS:  MicroRNA were isolated from six frozen non‐cancerous surrounding colonic tissues derived from stage II–III colon cancer patients with (n = 3) and without (n = 3) lymph node metastasis. We compared the microRNA expression profiles of the six non‐cancerous colonic tissues from two colon cancer patient groups; those with confirmed lymph node metastasis, termed the lymph node positive group, and those without detectable lymph node metastasis, termed the lymph node negative group. MicroRNA expression was analyzed with Agilent microarrays containing 723 human microRNA probes. We validated the expression level of differentially expressed microRNA using quantitative real‐time PCR analysis.

RESULTS:  Two microRNA (hsa‐miR‐129*, hsa‐miR‐137) were differentially expressed in the lymph node positive group compared with the lymph node negative group. The expression level of hsa‐miR‐137 was quantified via quantitative real‐time PCR analysis for validation. Hsa‐miR‐137 expression was significantly upregulated nearly 6.6‐fold in lymph node positive specimens (P = 0.036). The quantitative real‐time PCR result correlates with the microarray finding.

CONCLUSION:  The non‐cancerous colonic tissues from colon cancer patients with lymph node metastasis have a significantly different microRNA expression profile compared to that from colon cancer patients without lymph node metastasis. The differentially expressed microRNA could have relevance to the lymph node metastasis of colon cancer and may provide a simple profiling method to assist in identifying patients with lymph node metastasis. Besides, these data might offer new ideas for preventing and controlling lymphatic metastasis in colon cancer.
Modeling of Pumping Performance of Labyrinth Screw Pump (LSP) by 2D Reynolds Stress Equations
Authors: Ma Runmei , Wang Kuisheng
Published: July 2009

By using Prandtl’s mixing length theory to model two-dimensional Reynolds stress equations, the pumping performance of a labyrinth screw pump (LSP) is studied and several key parameters are empirically determined. As a result, two innovative concepts, a cell head coefficient Kf and a pump total head coefficient Kb, are proposed. A simple empirical equation quantifying the effects of the main geometric parameters of the threads on the pump performance is obtained and compared with Golubiev’s experimental results (1965, “Studies on Seal for Rotating Shafts of High-Pressure Pumps,” Wear, 8, pp. 270–288; 1981, Labyrinth-Screw Pumps and Seals for Corrosive Media, 2nd ed., Mashinostroenie, Moscow, pp. 34–49). Both theoretical study and Golubiev’s results indicate that with an increase in screw lead, Kf increases while Kb decreases. Kf is inversely proportional to power of screw-sleeve relative diametrical clearance, and the power exponent varies with different shapes of thread. Finally, Kf decreases with an increase in the relative depth of the thread groove over a wide range. Furthermore, some empirical relations between Kf and screw lead, the screw-sleeve relative diametrical clearance and the relative depth of thread groove are fitted, respectively, based on the derived relation between Kf and thread geometric parameters and Golubiev’s experimental data, which would provide a theoretical basis for LSP design.
Single Channel Hybrid FES Gait Assist System
Authors: Kangude A. , Burgstahler B. , Katsys J. , Durfee W.
Published: July 2009

Loss of mobility due to lower limb paralysis is common consequence of thoracic level spinal cord injury (SCI). In the US there are approximately 253,000 persons with SCI. The wheelchair is the most common form of mobility for individuals with paraplegia but there remains a need for assistive technology that can enable paraplegics to walk and reach in the periphery of wheelchair. A new concept is presented that combines functional electrical stimulation (FES) with an energy storing orthosis (ESO) that contains a fluid power system to store and transfer energy during the gait cycle. Elastic energy storage elements on the orthosis hip and knee joints hold the leg in a flexed equilibrium position. Stimulation of the quadriceps extends the knee, placing excess energy in both the equilibrium spring and an energy transfer element. The stored energy is transferred to the hip where it is discharged and used to extend the hip against its equilibrium spring which also aids in forward progression. A new step is initiated by releasing the hip and knee joints from the straight leg position to the flexed position. The concept is realized using gas springs and pneumatic cylinders. Gas springs act as flexed energy storage elements. Lower air cylinder and the tubing acts as an accumulator and the upper cylinder acts as hip joint actuator. The system uses 2 way proportional solenoid actuated pneumatic valves for control during extension. The conceptual design of the ESO was completed and implemented in a dynamic simulation model (MSC ADAMS) and in a benchtop prototype for engineering measurements. Of the 14 joules of energy available from quadriceps, 8.9 joules of energy is utilized for doing work against springs and inertial forces; 5.4 joules is stored in pneumatic system; of which 1.4 joules is required for hip extensions and the remaining will be used for forward progression. No studies were conducted with human subjects. A hydraulic fluid power system was investigated for better control and braking possibilities but was not adopted because of difficulities in accumulator design and high fluid friction losses. A Matlab code was used to calculate the torques required at joints to support standing. Commerical braces are being used for improved user comfort. A wrap spring brake is being designed to maintain standing posture without FES or any active energy input. Technical feasibility of the ESO prototype will be evaluated using two subjects with paraplegia.
Laparoscopic Image Guidance via Conoscopic Holography
Authors: Lathrop R. A. , Cheng T. T. , Webster R. J.
Published: July 2009

Spatially registered 3D preoperative medical images can improve surgical accuracy and reduce reliance on memory and hand-eye coordination by the surgeon. They enable visualization of internal structures within the anatomy of a patient on the operating table. In the case of biopsy, for example, this would allow the surgeon to guide the needle tip to a tumor though opaque tissue. It has been well established that for soft tissues, image registration can be performed by aligning the preoperative image with a cloud of points that describe the surface of an organ [1]. Collecting this point cloud can be challenging, generally requiring open surgery to permit line-of-sight access for laser triangulation (e.g., the system of Pathfinder Therapeutics, Inc.). We present a conoscopic holography-based system for collecting a point cloud less invasively-through a laparoscopic port. The system consists of a commercial conoscope (Optimet, Inc., Probe Head Mk3), designed for precision machine-shop linear measurements, that is tracked (the surgical tool is also tracked) with an optical tracking system (Claron Micron Tracker H3-60). The conoscope laser beam can, in principle, be aimed through a laparoscopic port. The 1 degree of freedom linear distance measurements it returns are converted into a point cloud using optical tracker information. Proof-of-concept for obtaining point clouds via conoscopic holography and registering them to known shapes is provided in [2]. However, the procedure for collecting these point clouds requires the surgeon to manually `paint' the surface of the organ with the laser beam, aiming it at many points on the surface by manipulating the conoscope base unit, thus pivoting the tube in the laparoscopic port. It would be desirable to relieve the surgeon of this task by creating a system for automatically aiming the laser beam from a stationary conoscope. We hypothesize that this can be done with a suitably designed actuated mirror assembly at the tip of the laparoscopic tube. To assess whether a conoscope can make an accurate distance measurement when reflected by a mirror, we conducted a set of experiments. We placed a front-silvered mirror at a fixed 45 degree angle relative to the conoscope, 12 cm in front of it. Total beam length was 185-315 mm measured in 10 mm increments. The results were similar to direct measurements of the same distance without a mirror. We recorded a standard deviation of error of less than 0.01 mm in each 10 mm increment. A second experiment was then carried out to assess the effect of mirror angle. The laser was swept across a flat surface 105 mm from the mirror by rotating the mirror. The standard deviation of the data points from a true line was less than 0.1 mm along a 175 mm line segment. These experiments indicate the feasibility of using a mirror to aim a conoscopic holographic laser, paving the way for an automatic laparoscopic laser, paving the way for an automatic laparoscopic point cloud collection device to be developed in future work.
The Neural Nanoprobe: Physically Decoupling the Neural Recording Site From the Headstage
Authors: Al-Ashmouny K. M. , Boldt C. , Ferguson J. E. , Redish A. D. , Yoon E.
Published: July 2009

The ability to record neural ensembles from awake, behaving animals is one of the most important and successful components of the neuroscience experimental toolbox. However, even the most advanced modern systems have limitations due to the physical coupling of the recording site with the headstage. These systems can only record from a limited number of structures at any one time and have particular difficulty recording large ensembles from animals with thin skulls (e.g., mice, songbirds). Current systems cannot record from fragile structures (spinal cord, peripheral nerves and ganglia) during behavior because the wire electrodes would shred the fragile nerves as the animal moves. We propose the concept of a neural nanoprobe that is physically decoupled from a separately implanted waystation. Because the nanoprobes are not connected to the waystation by physical wires, multiple nanoprobes could be placed in multiple neural structures, all transmitting to a single, separate waystation. Because the nanoprobes effectively float in the cellular matrix, they are safe to put in fragile structures. The waystation does not need to be implanted in the fragile structures; it only needs to be electrically coupled to them. The first step to the realization of this device is a low-power, high-fidelity method for communicating between the nanoprobe and the waystation. In this abstract, we report a successful test proving the viability of using the brain itself as the conducting medium through which the nanoprobe and waystation can communicate. Initial tests show that neural signals from multiple transmission sites can be sent to a single, separated receiver. We first identified the current-loss of sine-waves transmitted through live (anesthetized) brain tissue. We found negligible current-loss across frequencies ranging from 100 kHz–50 MHz across distances as much as 15 mm. As these frequencies are larger than any known frequencies used by neural signals, they are unlikely to interfere with neural function. We next measured the ability to transmit and receive pre-recorded neural signals (sampled at 20 kHz), using pre–recorded signals to determine the fidelity of transmission. The two different signals were transmitted, received, and successfully demodulated with high-fidelity, even with transmission currents as low as 2 μA. Both the transmitters and the receiver each had their own battery power supply to ensure that they used separate, floating grounds. Finally, to ensure that the intra-brain communication signals did not interfere with neural activity, we recorded extra-cellular potentials before, during, and after the test. No changes were observed in spike shape, spike frequency, bursting, or other cellular properties, demonstrating the safety of this technique. Supported by a grant from the Institute for Engineering in Medicine (U Minnesota) and training grant support from T90-DK070106. Corresponding author; email: redish@umn.edu
Molecular Imprinted Polymer for a Purfication Device
Authors: Bawazir A. A. , Moore B. D. , Gaylor J. D. S.
Published: July 2009

Molecular imprinting is a well established technology that mimics biological recognition systems using artificial materials. This involves synthesizing a nanostructured polymeric host in the presence of a target molecule to generate complementary binding sites that are selective for a molecule of interest. The technique offers a platform for developing simple and inexpensive systems with a vast array of applications such as; chromatography, separation, catalysts purification, solid phase extraction, biosensors, medical diagnostics and drug delivery. Elevated levels of some proteins in the blood can lead to a number of medical conditions. Incorporating these polymers into a device for blood purification to remove such molecules can be used as a means to combat these problems. Protein imprinting was studied from a novel perspective using protein coated micro crystals (PCMCs). PCMCs are nanostructured particles made via a rapid 1-step process developed by Moore et al. (2001). The use of a novel PCMCs strategy in molecular imprinting has allowed the retention of selected protein native conformation in organic media and the creation of access pores lined with nanocavities which facilitate protein extraction and re-introduction into the imprinted polymer. This technique has enabled us to overcome many of the challenges faced when using conventional imprinting methodology, such as protein insolubility in aprotic solvents, protein insolubility in aprotic solvents, protein denaturation and aggregation as a result of polymerization conditions and the permanent entrapment of the protein template in the cross linked polymer network.
Bioactive Magnetoelastic Materials as Coatings for Implantable Biomaterials
Authors: Vlaisavljevich E. , Janka L. , Ong K. , Rajachar R.
Published: July 2009

Enhanced fibroblast activity at the soft tissue-implant interface can dramatically decrease the stability, function, and lifespan of biomedical implants such as bone anchored prostheses. Although bone anchoring systems dramatically improve prosthetic limb mechanical stability, uncontrolled fibrosis at the soft tissue-mounting post interface is a significant problem. The aberrant cell growth leads to irregular skin folds that prevent proper sealing to the bone anchoring post and also serves as a site for opportunistic infection and failure of the prosthetic system. We are developing a bioactive vibrational coating to control fibrous tissue overgrowth. The coating is based on a magnetoelastic (ME) material that can be set to vibrate at a predetermined amplitude and frequency using a controlled magnetic field. We hypothesize that small local vibrations can be used to selectively control cell adhesion and gene expression to promote and maintain functional stability at the implant-tissue interface. For bone anchored prostheses, the ME coating would be applied around the mounting post at the soft tissue interface. The specific aims of this work were to (1) modify the coating for use in contact with a biologic environment and (2) determine if local vibrational strain can efficiently control cell attachment to the coating without significantly influencing viability. First, two common biocompatible polymers, polyurethane and chitosan, were deposited as thin films on the ME coating to allow for its use in tissue culture. An indirect cytotoxicity test was used to determine fibroblast (L929) viability in media conditioned for 24 and 48 hours with uncoated, chitosan coated, and polyurethane coated ME materials. Results demonstrated that both polymer coatings returned cell survival to levels statistically indistinguishable from controls (cells cultured on tissue cultured polystyrene, TCP) with cell viability over 96% under all coating conditions. Second, the affect of local vibrations on cell adhesion was tested in vitro. A cell viability assay (Calcein-AM) followed by fluorescent imaging was used to quantify attachment and viability of fibroblasts cultured directly on the bioactive ME material. Results clearly indicated that controlled local vibrations can induce complete cell detachment from the ME material compared with non-vibrated controls at up to 72 hours post-seeding. Further, cells detached via applied vibrations showed no significant decrease in viability compared to adherent controls. These results suggest the potential for this novel coating to effectively control fibrous tissue overgrowth using the mild application of tunable local vibrations, a significant and cost-effective approach that could improve the stability, function, and lifespan of biomedical implants and reduce the need for surgical revision.
RF Magnetic Signal Localization at Very High Magnetic Field Systems
Authors: Yoo H. , Delabarre L. , Gopinath A. , Vaughan J. T.
Published: July 2009

The impetus of this work originated from the advent of high magnetic field magnetic resonance imaging scanners with B0 fields of 4T, 7T, and 9.4T. These ultrahigh magnetic field systems generally improve the signal to noise ratios. However, B1 field non-uniformity also occurs due to the increased RF field frequencies when wavelengths in the head become shorter than its size. As interest in multiple channel transmission line coils increases, the control of the amplitude and phase of individual coil elements is required in order to develop desired B1 field. The choice of the excitation of the coil elements may be determined by convex optimization. Convex optimization is used provides results very fast, when the problem is formulated globally. In addition, convex optimization provides better signal to noise (SNR) ratio when anatomic specific regions are investigated. In this paper, simulation and experimental results are discussed at 9.4T systems based on the number of elements. The primary objective of this study is to increase the signal in a specific target region and decrease the signal and noise in the outside region termed the suppression region. The convex formulations are minimizing the maximum field point in the suppression region while keeping the center of target maximum. Based on this min-max optimization criterion, an iteration method which modifies the selection of suppression fields is also performed to produce better results. The results of the localization on FDTD human data at 9.4T are shown in Fig. 1. In these figures, the axial slices of the center of human head model provided by XFDTD are used after manipulating with MATLAB and the 16 channel head coil is excited. Figure 1 shows an improvement of the homogeneity in the suppression region when the target region is at center. In Fig. 2, received signal localizations are obtained for three different regions of interest (ROI) after using the convex optimization. Note that the selection of ROI is limited by the geometric setting of phantom in the 8-channel TEM head coil. Convex optimization with an iterative method was performed on both the human head and phantom models with operating frequency 400 MHz to design coil channel excitation parameters. By applying the iterative method to the convex optimization, more homogeneous B1 fields are obtained in the suppression region for 9.4T system.
Arthroscopic Sheath Design and Technical Evaluation
Authors: Tuijthof Gabriëlle J. M. , Blankevoort Leendert , Herder Just L. , Niek van Dijk C.
Published: July 2009

The maintenance of a clear view on the operation area is essential to perform a minimally invasive procedure. In arthroscopy, this is achieved by irrigating the joint with a saline fluid that is pumped through the joint. At present, the arthroscopic sheaths are not designed for optimal irrigation, which causes suboptimal arthroscopic view. The goal of this study is to present new design concepts and their technical evaluation to optimize irrigation. We focused on decreasing the fluid restriction and stimulating turbulent inflow streams. This is achieved by combining analysis of clinical practice, fluid mechanics theory, and experiments. A distinction is made between a three- and a two-portal technique. For a three-portal technique, the design concept consisted of a conventional sheath (∅4.5 mm) used with a smaller diameter arthroscope (∅2.7 mm). This resulted in a decreased fluid restriction. For the two-portal technique, a partition is designed, which separates the inflow and outflow streams in this sheath. Practical embodiments of the concepts are evaluated experimentally, in comparison with conventional sheaths. The setup consisted of a simulated arthroscopic operative setting of a knee joint. The main discriminating measures are the irrigation time, the fluid restriction, the flow, and the pressure in the joint. The results show that the proposed concept for the three-portal technique decreased the irrigation time significantly by 25%, and the concept with the partition for the two-portal technique decreased the irrigation time by 67% (analysis of variance, p<0.05). Different sheath tips showed no significant differences, leaving the straight shaft as the preferred embodiment. The simulation environment proved to be a suitable platform to test devices in a conditioned setting. The new sheath is expected to be a valuable improvement in achieving optimal irrigation.
Policy-Induced Constraints in the Design and Commercialization of Monitoring Devices: An Assessment of Three Technologies’ Reimbursement Models
Authors: Rao Sunil K. , Pietzsch Jan B.
Published: July 2009

Successful commercialization of medical technologies increasingly requires developers and manufacturers to think early-on about regulatory approval and reimbursement strategies for their new devices. This can be particularly challenging in the case of monitoring devices, where demonstrating the effectiveness and finding the coding and coverage can often be a complicated and lengthy process, particularly with the given current reimbursement policy. In this paper, we use three technology case studies to examine how firms are navigating the status quo and illustrate the importance of incorporating a comprehensive understanding of current market and regulatory constraints into the development and commercialization process. The case studies suggest that viable approaches can include pairing a monitoring technology with a therapy, or relying on hospital-pay or patient-pay models that are based on demonstration of direct benefits or cost-savings to these parties. The results emphasize that successful innovation in monitoring technologies increasingly requires a very closely aligned engineering, business, and health-economic strategy. Developing a comprehensive understanding of the specific value drivers and policy-induced constraints can contribute substantially to achieving the true benefits of monitoring technologies.
Intra-Operative Pulse Oximetry
Authors: Oliveira L. , Servais E. , Rizk N. , Adusumilli P. , Bikson M.
Published: July 2009

Bowel resection surgery is a commonly performed operation used to treat a variety of gastro-intestinal tract disorders, including cancer. The surgery entails excising the diseased portion of intestine, and then creating a surgical anastomosis, or reattachment of the remaining ends. One of the major complications following bowel resection surgery is breakdown or leakage from the anastomosis, which affects 20% of patients, with an associated 10-15% mortality rate. The surgical creation of anastomosis frequently involves dividing blood vessels and can introduce unrecognized twists and tension on the intestine. As a result, the blood supply to the site of anastomosis is often hampered, limiting the oxygen supply that is essential for adequate anastomotic healing. We are proposing a device that enables surgeons to obtain real-time feedback on local tissue oxygen saturation (SpO2) during operative procedures. Such data will not only help surgeons realize any bowel oxygenation compromising maneuvers, but also help perform an anastomosis at the site of maximal tissue oxygenation, thus minimizing the occurrence of postoperative anastomotic leakage and improve patient outcomes. This report details the specifications, fabrication, operation and performance of a handheld wireless pulse oximeter suitable for the intraoperative measurement of tissue SpO2 during bowel surgery. The device adapts principles and technology developed for non-invasive pulse oximetry, and introduces tissue interface, physician tools, and signal processing algorithms for intra-operative application. The handheld device includes local display of SpO2 level (<1s refresh) at the contacted tissue, and signals the operator on degraded signal quality/faults. An onboard micro-controller digitizes and processes signals transduced through a controlled LED array. Signal processing and display parameters were optimized for operating room conditions. A disposable functionally-transparent cover provides both device and tissue protection. Through serial or Bluetooth wireless transmission (250 Kbps), SpO2 and pulse signals can be processed on a PC or operating room VI. The incorporation of a pressure sensor to increase accuracy and robustness is explored. The device was validated intra-operatively on rodent and bovine surgical models.
Efficient Design Testing With Statistical Concept of Degree of Freedom
Authors: Goh Thong N.
Published: July 2009

Efficient testing of design prototypes or early batches of products is essential to meeting time-to-market as well as field performance and other requirements such as those specified in environmental and safety standards. Most design engineers are concerned with the technical arrangements and execution of such tests but may not be making use of an approach based on information transformation that is better known to statisticians in the form of experimental design. In this paper, we suggest the use of strategies and tools of experimental design from the perspective of information utilization, and highlight ways in which specific performance characteristics of a new or improved product can be effectively and efficiency tested, quantified, and evaluated. The approach also bridges the usual gap that exists between design engineers and mathematical statisticians, as traditionally each profession tends to have its own parlance and mindset in empirical studies. The techniques illustrated in this paper tend to “fall through the crack” in various texts on empirical product testing; they help put in place a framework that can be fruitfully adopted by design engineers who do not necessarily have an extensive background in statistics. Knowledge of this framework is essential today when on one hand, time for product development, testing and evaluation is short in a globalized market, while on the other is the prevalence of computing hardware and software that has virtually eliminated the chores of data-crunching arising from product evaluation and proofing activities.
Handling Module of Glass Slide for Whole Human Genome Micro-Array Automated Hybridization Platform
Authors: Jiang Jinq-Yu , Huang Chun-Hung
Published: July 2009

A micro-array based automated hybridization platform, ITRI HybOne, with the throughput rate of 12-sets per lot has been proposed and developed for whole human genome expression profiling test. A special handling module has been designed for capturing of Whole Human Genome Micro-array which is a glass slide 75mm in length and 25mm in width and 1mm in thickness. According to the user-defined protocol, an operator can set the heating temperature, washing temperature, heating hours and washing hours before starting the profiling test. Operator inputs target samples and micro-arrays to ITRI HybOne, pushes the Cycle-Start button to start. With the help of the handling module and other automatic devices, after hours of automatic process, the micro-arrays are ready for profile scanning. All the handling modules used in the platform are recycled for next profiling test.
Development of a Rigid Ring Quarter-Vehicle Model With an Advanced Road Profile Algorithm for Durability and Ride Comfort Predictions
Authors: Allen James , El-Gindy Moustafa , Koudela Kevin
Published: July 2009

In this paper a new five-degree-of-freedom in-plane Rigid Ring Quarter-Vehicle Model (RRQVM) with a Force Dependent Effective Road Profile (FDERP) is derived and programmed in MATLAB/Simulink©. This novel fully integrated model uses the tire-road vertical contact force to update the effective road height and slope at each integration time step. The model is capable of simulating the response of a free rolling tire over arbitrarily uneven road surfaces to study vehicle ride comfort and durability with efficient, accurate results. The RRQVM is validated with tire spindle vertical acceleration data from virtual Finite Element Analysis (FEA) Quarter-Vehicle Model (QVM) tests. A baseline in-plane RRQVM with a Force Independent Effective Road Profile (FIERP) is also developed for comparison with the FDERP RRQVM. Results show that the FDERP RRQVM predicts the vertical tire spindle acceleration more accurately than the FIERP RRQVM when compared to the FEA RRQVM results, especially at speeds above 11 km/hr. Therefore, the advanced FDERP model provides the RRQVM with a more accurate effective road profile than a conventional FIERP model.
Moving Pivot Specification for Three Precision Position Planar Linkage Synthesis
Authors: Wanner John T. , Sherman Andrew E. , Fisher Benjamin J. , Chase Thomas R.
Published: July 2009

An analytical solution to moving pivot specification of motion generating dyads at three precision positions is derived using the complex number formulation. This solution enables replicating the functionality of a well-known graphical construction for three position synthesis. It complements an existing complex number based solution for ground pivot specification. The solution is demonstrated by a practical example of designing a vehicle suspension linkage. The example also demonstrates how moving pivot specification can be applied to synthesize multiloop linkages.
A Load Independent Pseudo-Rigid-Body 3R Model for Determining Large Deflection of Beams in Compliant Mechanisms
Authors: Su Hai-Jun
Published: July 2009

Modeling flexible beams that undergo large deflection is one of the key steps in analyzing and synthesizing compliant mechanisms. Geometric nonlinearities introduced by large deflections often complicate the analysis of mechanism systems comprising such members. Several pseudo-rigid-body (PRB) or multi segment models in the literature have been proposed to approximate the tip deflection and slope. However these models are either dependent on external loads or too complicated to analyze. They are neither appropriate for analyzing mechanisms in which loads change significantly as they move, nor for synthesizing mechanisms where a parametric model is preferred. In this paper, a load independent PRB 3R model which comprises of four rigid links joined by three revolute joints and three torsion springs is proposed. The traditional PRB 1R models are first studied for both small deflection beams and large deflection beams. These studies provide fundamental insights to the geometric nonlinearity of large deflection beams. Numerical integration is applied to compute tip deflections for various loads. A three-dimensional search routine has been developed to find the optimal set of characteristic radius factors for the proposed PRB 3R model. Detailed error analysis and comparison against the result by the numerical integration and the PRB 1R model are accomplished for different load modes. The benefits of the PRB 3R model include (a) high accuracy for large deflection beams, (b) load independence which is critical for applications where loads vary significantly and (c) explicit kinematic and static constraint equations derived from the model. To demonstrate the use of the PRB 3R model, a compliant 4-bar linkage is studied and verified by a numerical example. The result shows a maximum tip deflection error of 1.2% compared with the FEA model.
An Analytical Design Method for a Shape Memory Alloy Wire Actuated Compliant Finger
Authors: Lan Chao-Chieh , Yang You-Nien
Published: July 2009

This paper presents an analytical method to design a mechanical finger for robotic manipulations. As traditional mechanical fingers require bulky electro-magnetic motors and numerous relative-moving parts to achieve dexterous motion, we propose a class of fingers the manipulation of which relies on finger deflections. These compliant fingers are actuated by shape memory alloy (SMA) wires that exhibit high work-density, frictionless, and quite operations. The combination of compliant members with embedded SMA wires makes the finger more compact and lightweight. Various SMA wire layouts are investigated to improve their response time while maintaining sufficient output force. The mathematical models of finger deflection caused by SMA contraction are then derived along with experimental validations. As finger shapes are essential to the range of deflected motion and output force, we find its optimal initial shapes through the use of a shape parameterization technique. We further illustrate our method by designing a humanoid finger that is capable of three-dimensional manipulation. As compliant fingers can be fabricated monolithically, we expect the proposed method to be utilized for applications of various scales.
Synthesis of Adjustable Linkages for Precise Path Generation Using the Optimal Pivot Adjustment
Authors: Zhou Hong , Castillo Thomas
Published: July 2009

Regular nonadjustable four-bar linkages can only generate the desired continuous paths approximately. The whole desired continuous path can be generated precisely by an adjustable four-bar linkage with the one-degree-of-freedom adjustment of the pivot location of the driven side link. In this paper, an adjustment R joint is used to adjust the pivot location of the driven side link in the four-bar linkage. A closed-loop 5R linkage is formed by the adjustable four-bar linkage. The linkage feasibility conditions and path generation flexibilities of the adjustable four-bar linkages are analyzed. The synthesis model of the adjustable four-bar linkages is set up based on the required optimal adjustment of the pivot location when the desired continuous path is precisely generated. The global optimal solution is searched by a genetic algorithm in which the involved constraints are handled using the function penalty method. The effectiveness of the synthesis approach proposed in the paper is verified by two demonstrated examples.
Geometric Synthesis of Spatial Compliant Mechanisms Using Three-Dimensional Wide Curves
Authors: Zhou Hong , Ting Kwun-Lon
Published: July 2009

A three-dimensional wide curve is a spatial curve with variable cross sections. This paper introduces a geometric synthesis method for spatial compliant mechanisms by using three-dimensional wide curves. In this paper, every connection in a spatial compliant mechanism is represented by a three-dimensional wide curve and the whole spatial compliant mechanism is modeled as a set of connected three-dimensional wide curves. The geometric synthesis of a spatial compliant mechanism is considered as the generation and optimal selection of control parameters of the corresponding three-dimensional parametric wide curves. The deformation and performance of spatial compliant mechanisms are evaluated by the isoparametric degenerate-continuum nonlinear finite element procedure. The problem-dependent objectives are optimized and the practical constraints are imposed during the optimization process. The optimization problem is solved by the MATLAB constrained nonlinear programming algorithm. The effectiveness of the proposed geometric procedures is verified by the demonstrated examples.
A General Formula of Degree of Freedom for Parallel Mechanisms
Authors: Yang Ting-Li , Sun Dun-Jin
Published: July 2009

In this paper, a general formula of degree of freedom (DOF) for parallel mechanisms has been presented which could provide the full-cycle DOF. The key parameters in the formula can be determined via the position and orientation characteristic equations and their symbolic operations of serial and parallel mechanisms proposed by author and the symbolic operation is simple. It is totally different from the methods based on screw theory and based on displacement subgroup. The formula has been used for selection of driving pairs and determination of idle pairs. The formula may also be used for determining the DOF of other multi-loop mechanisms besides parallel mechanisms.
Reduced Models for the Active Vibration Control of Light Structures
Authors: Gouttebroze C. , Louf F. , Champaney L.
Published: July 2009

The vibration control of mechanical structures is an important issue for the preservation of their structural integrity, especially in the case of light structures such as electronic cards aboard flying vehicles. One of the most effective methods in this domain is active vibration control, which requires an observation of the structure and an adequate command. Therefore, one must use a satisfactory numerical model of the structure. One way of achieving such a model consists in improving a given initial model. The governing principle of the updating method used in this paper, based on the modified constitutive relation error principle [1, 2], consists in dividing the equations of the problem into two groups: a reliable group and an unreliable group. Then, among the mechanical fields which verify the equations of the reliable group exactly, one seeks the field which minimizes a norm containing the residuals of the unreliable group and some distance between the observed experimental data and the numerical results. Like many other widely used updating techniques [3, 4], this is an optimization-based method whose objective function has a very high calculation cost. In-flight updating requires rapid calculations; therefore, the cost function must be approximated. In order to do that, we use vector spaces over a field of truncated rational functions of multiple variables. Tensor manipulations on such vector spaces lead to very-low-cost, rational objective functions. Furthermore, this technique enables one to calculate the gradient and higher-order derivatives of the cost function very inexpensively, leading to very efficient minimization algorithms. In this paper, we illustrate the method by updating a beam. This is a simple problem, but one which is representative of the updating of electronic cards. The beam is instrumented with piezoelectric sensors and actuators, which are taken into account in the numerical model. The experimental data are simulated by applying perturbations to the stiffness, damping and/or mass parameters in the beam itself, in the piezoelectric components or at the boundaries.
One and Two Dimensional Data Analysis Using Bezier Functions
Authors: Venkataraman P.
Published: July 2009

Bezier functions, which are Bezier curves constrained to behave like functions, are excellent for representing smooth and continuous function of high degree, over the entire range of the independent variable. They provide excellent solutions to systems of linear, nonlinear, ordinary and partial differential equations. In this paper we examine their usefulness for data approximation as a prelude to their use in solving the inverse problem. Bezier function and B-splines, which are related, have mostly been used in geometrical modeling. There are not many examples of their use in data analysis. In this paper, organized and unorganized data are used to illustrate the effectiveness of Bezier functions for data approximation, reduction, mining, transformation, and prediction. Two criteria are used for the overall data fitting process. A simple incremental strategy identifies the order of the function using the minimum of the sum of the absolute error over all data. For a given order of the function, the least squared error over all data identifies the Bezier function through a non iterative algebraic relation. The entire data can then be represented by the coefficients of the Bezier function. Alternately, the data can also be reduced to a polynomial based on a parameter varying between 0 and 1. The Bezier function is global over all of the data so that all data points, including interpolated data, have the same properties. Three important properties are explicit is using Bezier functions for data analysis. The mean of the original data and the approximate data are the same. Large orders of polynomials can be used without local distortion. The independent and dependent variables can be decoupled by the Bezier representation. The data fitting process can also filter noisy data to recover principal data behavior.
On the Terminology for Redundant Parallel Manipulators
Authors: Mu¨ller Andreas
Published: July 2009

Different types of redundancy in parallel kinematics machines (PKM) can be used to improve their kinematic and dynamic properties. The meaning of redundancy of PKM is often differently understood in the literature. In this paper a terminology for redundant PKM is proposed. The basis for this classification is a general mathematical model. With the help of this model PKM are regarded as non-linear control systems. The different types of redundancy are clearly distinguished, and their potential applications are discussed. Redundancy is considered from a geometric point of view. Redundancy is a means to deal with singularities of PKM. The different types of singular configurations are considered in the paper, and the potential of redundancy to cope with such situations is discussed. Again singularities are considered from a geometric point of view.
Should Designers Worry About Market Systems?
Authors: Shiau Ching-Shin , Michalek Jeremy J.
Published: July 2009

Engineering approaches for optimizing designs within a market context generally take the perspective of a single producer, asking what design and price point will maximize producer profit predicted by consumer choice simulations. These approaches treat competitors and retailers as fixed or nonexistent, and they take business-oriented details, such as the structure of distribution channels, as separate issues that can be addressed post hoc by other disciplines. It is well established that the structure of market systems influences optimal product pricing. In this paper, we investigate whether two types of these structures also influence optimal product design decisions; specifically, 1) consumer heterogeneity and 2) distribution channels. We first model firms as players in a profit-seeking game that compete on product attributes and prices. We then model the interactions of manufacturers and retailers in Nash competition under alternative market structures and compare the equilibrium conditions for each case. We find that when consumers are modeled as homogeneous in their preferences, optimal design can be decoupled from the game, and design decisions can be made without regard to price, competition, or channel structure. However, when consumer preferences are heterogeneous, the behavior of competitors and retailers is key to determining which designs are profitable. We examine the extent of this effect in a vehicle design case study from the literature and find that the presence of heterogeneity leads different market structures to imply significantly different profit-maximizing designs.
Computer-Aided Fixture Planning: A Review
Authors: Kang Xiumei , Peng Qingjin
Published: July 2009

Fixture planning is a complex activity restricted by the extreme diversity of workpieces and constraints of design geometry, part accessibility, working force, and component deformation. This paper reviews major approaches to computer-aided fixture planning (CAFP). Geometry methods, kinematical analysis, force analysis, deformation analysis, case-base reasoning, fixture assembly planning, feature-based methods, rule-based methods and optimization methods are surveyed. The CAFP systems are summarized as CAD-based systems and Web-based systems. Some promising research areas are identified in respect of fixture design, assembly planning and virtual fixture planning.