bluuebunny/crossref_metadata_2025 huggingface dataset:
How allometric scaling relates to soil abiotics
Authors: Mulder Christian , Vonk J. Arie , Den Hollander Henri A. , Hendriks A. Jan , Breure Anton M.
Published: March 2011

For most species, the logarithm of their average body mass is negatively related to the logarithm of their relative population density, i.e. the numerical abundance. In this way, the allometric scaling (both mass–abundance regressions and body–size spectra) becomes useful in ecological theory to build and explain food webs. Using empirical evidence derived from 145 Dutch sites, a hypothesis is formulated to explain how soil microbivores, detritivores and predators react to increasing resource availability. Shifts in size distribution, and subsequently changes in soil food‐web structure, are further discussed in the perspective of Holling's sequential interactions between basic system functions. We show that the allometric scaling and the averages of the (log‐transformed) prey:predator body‐mass ratios are reliable predictors for assessing faunal responses to nutrient availability. We view this work as a first attempt toward an extensive comparison of ecological processes in different soil systems.
Prudent males, group adaptation, and the tragedy of the commons
Authors: Kokko Hanna , Heubel Katja U.
Published: March 2011

For almost five decades three threads have coexisted in the evolutionary and ecological literature, with their links only recently becoming visible and some of them still not properly addressed. These are the levels of selection debate, the metaphor of the tragedy of the commons, and the evolutionary study of sexual conflict. We analyze the eco‐evolutionary dynamics of a curious system where an asexual all‐female fish species (the Amazon molly Poecilia formosa) requires sperm from other species as a developmental trigger, without utilizing the genes from sperm. The dynamics of such a system bear strong resemblance to host–parasite dynamics, and populations of the sexual ‘host’ species persist much better if males avoid mating with Amazons. However, such avoidance may compromise their current mating success, and if this is the case, prudent mating becomes an altruistic trait that helps to keep an accumulating problem of a competing species at bay, and Amazon‐free space can be seen to form a common good that a population should maintain for future generations. A model shows that the evolution of altruistic mating restraint is possible but selection for short‐term gains means that it will remain less than perfect. This helps to explain why the anomalous gynogenetic system can persist, but it also raises questions about what kinds of traits can be classified as adaptations when optimization is not perfect and traits evolve to achieve short‐term goals better than long‐term performance. Contributing to the levels of selection debate, we encourage researchers to study the implications of the different timescales involved in the eco‐evolutionary process.
Breastfeeding practices of Cameroonian mothers determined by dietary recall since birth and the dose‐to‐the‐mother deuterium‐oxide turnover technique
Authors: Medoua Gabriel Nama , Sajo Nana Estelle C. , Ndzana Anne Christine A. , Makamto Caroline S. , Etame Lucien S. , Rikong Honorine A. , Oyono Jean Louis E.
Published: March 2011

Exclusive breastfeeding during the first 6 months of infant's life is a public health recommendation and important factor for the promotion of optimal growth, health and behavioural development of each child. The accuracy of the mothers' self‐reported past infant‐feeding events was examined and compared with the isotopic dilution technique. Breastfeeding practices were assessed in a sample of 44 Cameroonian mother–infant pairs using dietary recall since birth. Intakes of breast milk and non‐breast milk water were measured in the same sample using the dose‐to‐the‐mother deuterium‐oxide turnover technique and compared with questionnaire. Results showed that mothers' self‐reported behaviour overestimates the exclusive breastfeeding rate. Seventy‐five per cent of the mothers who claimed to be exclusively breastfeeding were found to be predominantly or partially breastfeeding by the dose‐to‐the‐mother deuterium‐oxide turnover technique. Only 11% of the infants were exclusively breastfed, and the breast milk output was not significantly affected (P ≤ 0.05) by the mother's body composition. Mean intakes of breast milk and non‐breast milk water were 701 mL day−1 and 268 mL day−1, respectively. Introduction of non‐breast milk foods is associated with a reduction in the level of breast milk intake, but the difference in breast milk intake was not significant between exclusively and predominantly breastfed infants. In conclusion, the dose‐to‐the‐mother deuterium‐oxide turnover technique can be applied to validate the mother's reports of infant‐feeding practices, but non‐breast milk water intake by breastfeeding category still needs to be normalized.
Simple clinical targets associated with a high level of patient satisfaction with their pain management
Authors: Jao Kathy , McD Taylor David , Taylor Simone E , Khan Munad , Chae John
Published: March 2011

Introduction: We aimed to determine factors that are significantly associated with a high level of patient satisfaction with their pain management.

Methods: We undertook an observational study in a large metropolitan ED. Adult patients with a triage pain score of ≥4 (0–10 scale) were enrolled. Data collected included demographics, presenting complaint, pain scores every 30 min, whether nurse‐initiated analgesia was administered, the nature of the pain relief administered, time to first dose of analgesia, elements of staff communication and whether ‘adequate analgesia’ was provided (defined as a decrease in pain score to <4 and a decrease from the triage pain score of ≥2). The primary end‐point, determined at follow up within 48 h, was the level of satisfaction with pain management (6‐point scale: very unsatisfied–very satisfied).

Results: One hundred and sixty‐seven (82.7%) of 202 enrolled patients were followed up – mean (SD) age 46.4 (18.3) years, 75 (44.9%) men. Eighty‐one (48.5%) patients were very satisfied with their pain management. Only two clinical variables were significantly associated with a high level of satisfaction: receipt of ‘adequate analgesia’ (as defined) and specific communication regarding pain management. Forty‐four (58.7%) versus 37 (40.2%) patients who did/did not receive ‘adequate analgesia’, respectively, were very satisfied (difference 18.5%, 95% CI 2.3–34.7, P= 0.027). Seventy‐seven (53.9%) and four (16.7%) patients who were/were not advised by ED staff that their pain management was important, respectively, were very satisfied (difference 37.2%, 95% CI 17.7–56.6, P= 0.002).

Conclusions: Our ‘adequate analgesia’ definition might provide a useful clinical target, which, combined with adequate communication, might help maximize patient satisfaction.
A Population Pharmacokinetic–Pharmacodynamic Model for Simvastatin that Predicts Low‐Density Lipoprotein‐Cholesterol Reduction in Patients with Primary Hyperlipidaemia
Authors: Kim Jimyon , Ahn Byung‐Jin , Chae Hong‐Seok , Han Seunghoon , Doh Kichan , Choi Jeongeun , Jun Yong K. , Lee Yong W. , Yim Dong‐Seok
Published: March 2011

Abstract:  Simvastatin (SV), a HMG‐CoA reductase inhibitor, is widely used for the treatment of hyperlipidaemia. The objectives of the present study were to develop a population pharmacokinetic–pharmacodynamic (PK‐PD) model for simvastatin and to evaluate its usefulness in predicting the dose–response relationship of simvastatin in patients with hyperlipidaemia. The data were obtained from a drug–drug interaction study to assess the effect of aspirin on the PK of simvastatin. Twenty‐seven healthy volunteers were given simvastatin 40 mg daily for 14 days in whom aspirin 100 mg q.d. was co‐administered after day 8. Full PK studies were performed on days 1, 7 and 14 in addition to trough sampling on days 5, 6, 12 and 13. Low‐density lipoprotein‐cholesterol (LDL‐C) levels were also measured serially. Then, a population PK‐PD model for simvastatin and its active metabolite, simvastatin acid (SVA), was developed using mixed effect methods (NONMEM Ver. 6.2). A simple linear PK model with parent and metabolite compartments provided the best fit for the 2647 concentrations of simvastatin and simvastatin acid, and a turnover model was used to describe the change in LDL‐C levels. The dose–response curve simulated from the final model and those obtained from the literature overlapped very closely. No influence of aspirin was observed in PK or PD. A simple PK‐PD model developed using only 2‐week study data from fewer than 30 healthy volunteers successfully predicted the dose–response relationship of simvastatin in patients when compared with published data.
Botanicals for the prevention and treatment of cutaneous melanoma
Authors: Syed Deeba N. , Mukhtar Hasan
Published: March 2011

Cutaneous melanoma, a cancer of melanocytes, when detected at later stages is arguably one of the most lethal cancers and the cause of more years of lost life than any other cancer among young adults. There is no standard therapy for advanced‐stage melanoma and the median survival time for patients with metastatic melanoma is <1 yr. An urgent need for novel strategies against melanoma has directed research towards the development of new chemotherapeutic and biologic agents that can target the tumor by several different mechanisms. Recently, several dietary agents are being investigated for their role in the prevention and treatment of various forms of cancer and may represent the future modality of the treatment. Here, we have reviewed emerging data on botanicals that are showing promise for their potential inhibitory effect against cutaneous melanoma.
Can Coherence Generate Warrant Ex Nihilo? Probability and the Logic of Concurring Witnesses
Authors: VAN CLEVE JAMES
Published: March 2011

Most foundationalists allow that relations of coherence among antecedently justified beliefs can enhance their overall level of justification or warrant. In light of this, some coherentists ask the following question: if coherence can elevate the epistemic status of a set of beliefs, what prevents it from generating warrant entirely on its own? Why do we need the foundationalist’s basic beliefs? I address that question here, drawing lessons from an instructive series of attempts to reconstruct within the probability calculus the classical problem of independent witnesses who corroborate each other’s testimony. Starred section headings indicate sections omitted here, but available on the author’s USC website.
Fatigue Life Prediction of Different Fiber-Reinforced Composites Using Polynomial Classifiers
Authors: El Kadi H. , Deiab I. M. , Al-Assadi M.
Published: March 2011

Polynomial classifiers (PC) have already been shown to produce good fatigue life prediction for a specific composite under a variety of fatigue loading conditions. In this study, polynomial classifiers are used to predict the fatigue life in other composite materials not used in training. Different composite materials with a variety of fiber orientation angles are considered. The predictions obtained using PC are compared with the experimental results and are shown to be promising.
Monitoring Solar Home Systems With Pulse Width Modulation Charge Control
Authors: Williams Nathaniel J. , van Dyk E. Ernest , Vorster Frederik J.
Published: March 2011

With the high cost of grid extension and approximately 1.6 billion people still living without electrical services, the solar home system is an important technology in the alleviation of rural energy poverty across the developing world. The performance monitoring and analysis of these systems provide insights leading to improvements in system design and implementation in order to ensure high quality and robust energy supply in remote locations. Most small solar home systems now use charge controllers using pulse width modulation (PWM) to regulate the charge current to the battery. A rapid variation in current and voltage resulting from PWM creates monitoring challenges, which, if not carefully considered in the design of the monitoring system, can result in the erroneous measurement of photovoltaic (PV) power. In order to characterize and clarify the measurement process during PWM, a mathematical model was developed to reproduce and simulate measured data. The effects of matched scan and PWM frequency were studied with the model, and an algorithm was devised to select appropriate scan rates to ensure that a representative sample of measurements is acquired. Furthermore, estimation methods were developed to correct for measurement errors due to factors such as nonzero “short circuit” voltage and current/voltage peak mismatches. A more sophisticated algorithm is then discussed to more accurately measure PV power using highly programmable data loggers. The results produced by the various methods are compared and reveal a significant error in the measurement of PV power without corrective action. Estimation methods prove to be effective in certain cases but are susceptible to error during conditions of variable irradiance. The effect of the measurement error has been found to depend strongly on the duty cycle of PWM as well as the relationship between scan rate and PWM frequency. The energy measurement error over 1 day depends on insolation and system conditions as well as on system design. On a sunny day, under a daily load of about 20 A h, the net error in PV energy is found to be 1%, whereas a system with a high initial battery state of charge under similar conditions and no load produced an error of 47.6%. This study shows the importance of data logger selection and programming in monitoring accurately the energy provided by solar home systems. When appropriately considered, measurement errors can be avoided or reduced without investment in more expensive measurement equipment.
Distribution of Emerged Energy for Daylight Illuminate on Prismatic Elements
Authors: Yeh Shih-Chuan , Whang Allen Jong-Woei , Hsiao Horng-Ching , Hu Xi-Duo , Chen Yi-Yung
Published: March 2011

Prismatic elements are typical devices of natural light illumination system for redirecting and collecting daylight. Based on the principles of optics, this paper presents a simple mathematical matrix ray-tracing methodology through which a detailed intensity distribution of parallel light beam incident onto a right angled prism from different incident angles can be calculated precisely. We also present the distribution of the secondary emerged intensity from a prism illuminated by the emerged light of an adjacent prism. The direction, concentration, and distribution of intensity of the emerged light from the parallel light incident onto a surface of the right-angle prism, as well as daylight illuminate on a prismatic collector, are precisely calculated. The detailed calculation of the emerged light re-incident onto the adjacent prism or emerged out of the prismatic element presented that most of daylight are directly emerged out and are confined in some directions at earlier morning and afternoon, and the emerged light re-incident into the adjacent prism at noon around. This detailed calculation model of parallel light beam incident to a prismatic element can be applied to the hybrid natural light illumination system, as well as to the prism-relative solar illumination system for the improvement of efficiency.
Characterization of Rapidly Consolidated Titanium Diboride
Authors: Kothari Kunal , Radhakrishnan Ramachandran , Wereley Norman M.
Published: March 2011

This study reports on the microstructure and mechanical properties of titanium diboride (TiB2) that was rapidly consolidated via plasma pressure compaction (P2C®). Titanium diboride powder with 2.5 wt % of silicon nitride (Si3N4), as a sintering aid, was rapidly consolidated using P2C® to inhibit grain growth and ensure high strength and ductility of the consolidated material. The consolidated specimens were 93.5% of theoretical density. The microstructure of the consolidated material was characterized using optical microscopy, scanning electron microscopy, and wavelength dispersive spectroscopy. Oxygen concentration in the consolidated sample was 13.55% less than in the as-received powders. The flexure strength, fracture toughness, Young’s modulus, and Vickers hardness of the consolidated specimens were measured at room temperature and were found to be equivalent if not superior to those reported in the literature.
Extrapolation Techniques for Very Low Cycle Fatigue Behavior of a Ni-base Superalloy
Authors: Daubenspeck Brian R. , Gordon Ali P.
Published: March 2011

A combination of extrapolation and estimation techniques from both prior and current studies has been explored with the goal of developing a method to accurately characterize high-stress amplitude low cycle fatigue of a material commonly used in gas turbine blades with the absence of such data. This paper describes innovative methods used to predict high-temperature fatigue of IN738LC, a dual-phase Ni-base superalloy. Three sets of experimental data at different temperatures are used to evaluate and examine the validity of extrapolation methods such as anchor points and hysteresis energy trends. High-stress amplitude data points approaching the ultimate strength of the material were added to pre-existing base data with limited plastic strain to achieve a full-range data set that could be used to test the legitimacy of the different prediction methods. Each method is evaluated at a number of temperatures.
Dead-Time Compensation for Wave/String PDEs
Authors: Krstic Miroslav
Published: March 2011

Smith predictorlike designs for compensation of arbitrarily long input delays are commonly available only for finite-dimensional systems. Only very few examples exist, where such compensation has been achieved for partial differential equation (PDE) systems, including our recent result for a parabolic (reaction-diffusion) PDE. In this paper, we address a more challenging wave PDE problem, where the difficulty is amplified by allowing all of this PDE’s eigenvalues to be a distance to the right of the imaginary axis. Antidamping (positive feedback) on the uncontrolled boundary induces this dramatic form of instability. We develop a design that compensates an arbitrarily long delay at the input of the boundary control system and achieves exponential stability in closed-loop. We derive explicit formulae for our controller’s gain kernel functions. They are related to the open-loop solutions of the antistable wave equation system over the time period of input delay (this simple relationship is the result of the design approach).
Simulation of Deep Spherical Indentation Using Eulerian Finite Element Methods
Authors: Anderson D. , Warkentin A. , Bauer R.
Published: March 2011

Simulation of deep indentation, and the associated pile-up effects, requires a robust and accurate finite element model capable of naturally handling the large deformations present. This work successfully demonstrates that the Eulerian formulation is capable of accurately reproducing the forces and general material response of deep indentation. It was found that, in the absence of friction, sink-in dominates at indentation depths less than 1.1% of the indenter radius, there is a transition from sink-in to pile-up from 1.1% to 2.3% of the indenter radius, and pile-up is fully developed at indentation depths larger than 13.2% of the indenter radius for the 4340 steel workpiece and the 0.508 mm radius indenter presented in this work. Friction tended to marginally increase the sink-in and transition depths as well as reduce the material height at the onset of fully developed pile-up due to a reduction in the tensile radial strain directly under the indenter.
Predictive Modeling of the Dynamic Response of Electronic Systems to Shocks and Vibrations
Authors: Suhir E.
Published: March 2011

The published work on analytical (“mathematical”) and computer-aided, primarily finite-element-analysis based, predictive modeling of the dynamic response of electronic systems to shocks and vibrations is reviewed. Understanding the physics and the ability to predict the response of an electronic structure to dynamic loading has been always of significant importance in military, avionic, aeronautic, automotive, and maritime electronics. For the past decade, this problem has become important also in commercial, and, particularly, in portable, electronics in connection with accelerated testing on the board level of various surface-mount technology systems. The emphasis of this review is on the nonlinear behavior of flexible printed circuit boards experiencing shock loading applied to their support contours.
Tire-Soil Modeling Using Finite Element Analysis and Smooth Particle Hydrodynamics Techniques
Authors: Lescoe Ryan , El-Gindy Moustafa , Koudela Kevin , O¨ijer Fredrik , Trivedi Mukesh , Johansson Inge
Published: March 2011

New soil models for a tire-soil interaction are developed and compared. A rigid tire model is used to perform an extensive sensitivity study on the previously used Finite Element Analysis (FEA) soft soil (dense sand) to determine the importance of mesh size, soil plot size, and edge constraints. Furthermore, parameters for Smooth Particle Hydrodynamics (SPH) particles are determined for either complete or partial replacement of FEA elements in the soil model. Rolling resistance tests are then conducted for different FEA, SPH, and FEA/SPH soil models. Replacement of FEA elements with SPH particles is isolated as a variable and it is found that using a deeper amount of SPH particles increases rolling resistance while increasing the SPH particle density has little effect on rolling resistance.
Design Methodology of Heavy Truck Front Underride Protection Devices (FUPD)
Authors: Castellanos Manuel , Fedishen Chris , El-Gindy Moustafa , Atahan Ali
Published: March 2011

The Objective of this study is to explain a new methodology in the design of heavy vehicle front underride protection devices (FUPD). This methodology is targeted generating optimal solutions in a cost-effective manner. In this research project non-linear finite element models were created using LS DYNA FEA package to perform crash simulations between a small car and the front of the truck at various levels, starting from component model level and ending with full tractor-semitrailer model level. Comparison between the crash simulation results with and without FUPD cases was performed to assess the adequacy of the design at every level of the study. Based on the results obtained an efficient and confident methodology for the evaluation of heavy truck FUPD designs is proposed. Furthermore, the proposed evaluation criteria are recommended to be the pioneering standard for FUPD performance evaluation.
Damage Study of Copper Alloys Submitted to Vibration Tests
Authors: El Abdi Rochdi , Carvou Erwann
Published: March 2011

The main requirement for the connector materials used in electrical contacts and submitted to vibration mode is to maintain very low and stable electrical resistance. Wear and fretting corrosion are a major cause of connector failure and the main reasons influencing the reliability of the electrical system. If the use of coating materials in electrical contacts is widespread, the coatings disappear from the contact surfaces after a certain number of vibration cycles and the contact is carried out between the two basic substrates in contact at the interface. Our study relates to the contact resistance characterization under dynamic vibrations for a contact between a sphere and plane using high content copper alloys with no coatings. Only one contact part is subjected to a vibratory movement, the other part is fixed. The contact resistance is continuously measured during the test. An experimental study of contact resistance behaviour is undertaken in order to evaluate the influence of mechanical and electrical material properties on the degradation of conduction. The obtained results show that the hardness and the resistivity of the copper alloys used have a large influence on the component lifespan.
Finite Element Modeling and Analysis of Orthotropic Butt Welds
Authors: Mojtahed Masoud , Cai Qingtian
Published: March 2011

Butt welds with orthotropic behavior are widely applied in mechanical and structural designs. Since welds cannot always be perfect in practice, it is important to understand the weld’s stress behavior under different imperfect geometries. In this paper research has been performed to investigate the relationship between stress intensity factors and change of geometry of orthotropic butt welds. Finite element methods were applied to simulate weld geometries. The simulation was performed using ANSYS software assuming two beams are welded together with a discontinuity at the bottom of the weld. The combined beams and the butt weld are then considered to be one piece of glued structure. The discontinuity in the structure is used to model a crack and lack of weld penetration. By changing three important factors of the weld geometry under uniform axial static loads, the trend of stress intensity factor behavior versus change of geometry has been investigated. Both single and double sided butt welds were considered in this paper. The results of this investigation will be a helpful tool for design engineers in deciding the best weld geometry in applications.
The Direct Kinematics of Objects Suspended From Cables
Authors: Jiang Qimi , Kumar Vijay
Published: March 2011

This work addresses the problem for determining the position and orientation of an object with regular polygon suspended from n cables with the same length when the n robots form a regular polygon on the horizontal plane. First, an analytic algorithm based on resultant elimination is presented to determine all possible equilibrium configurations of the planar 4-bar linkage. As the nonlinear system can be reduced to a polynomial equation in one unknown with a degree 8, this algorithm is more efficient than numerical search algorithms. Then, considering that the motion of the 3D cable system in its vertical planes of symmetry can be regarded as the motion of an equivalent planar 4-bar linkage, the proposed algorithm is used to solve the direct kinematic problem of objects suspended from multiple cables. Then, case studies with three to six cables are conducted for demonstration. Finally, experiments are conducted for validation.
Magnetic Assistance for Suppressing Cross-Reactions Between Biomolecules in Immunoassay
Authors: Hong Chin-Yih , Yang Shieh-Yueh , Horng Herng-Er , Yang Hong-Chang
Published: March 2011

A method involving the use of magnetic nanoparticles to suppress the cross-reactions in immunoassay is developed. Antibodies are coated onto magnetic nanoparticles. These antibodies bind with target and non-target molecules. Once an alternative-current magnetic field is applied, magnetic nanoparticles oscillate with the magnetic field. The target and non-target molecules attached onto magnetic nanoparticles via antibodies experience a centrifugal force, which is against the association between antibodies and target/non-target molecules. Theoretically, the centrifugal force is proportional to the square of the frequency of the applied magnetic field. Thus, the strength of the centrifugal force can be manipulated by changing the frequency of the applied magnetic field. By well controlling the frequency of applied magnetic field, the centrifugal force can be stronger than the binding between antibodies and non-target molecules, but still weaker than that of target molecules. Consequently, the binding between antibodies and non-target molecules is broken by the centrifugal force.
Hybrid Transmission for Mobile Robot
Authors: Esmail Essam L.
Published: March 2011

This paper presents proposed designs of parallel hybrid transmissions with only one electric motor/generator (MG) and without any rotating clutches. The proposed motor/generator integrated hybrid transmission serves to regulate the engine’s effective gear ratio (engine rotational velocity versus vehicle velocity) by mixing the engine and electric motor powers through a power controlling device. The proposed design provides some of the benefits and flexibility of a power-split design but using conventional available components in a simpler mechanical layout that makes the design compact, mechanically simple, and operationally flexible. Three commonly used transmission gear sets are used for this purpose; Simpson, Ravigneaux, and Type-6206 gear sets. With an electronic control unit, eight major modes of operation including a regenerative braking capability are shown to be feasible in the proposed hybrid transmission; one electric motor mode, two engine modes, two engine/charge modes, and two power modes. Continuously variable transmission (CVT) capability is provided with the second engine/charge mode and with the second power mode. The second power mode can be further subdivided into three hybrid sub-modes that correspond to the direct drive, under-drive, and over-drive of a conventional automatic transmission. The feasibility of the proposed hybrid transmission is demonstrated with a numerical example employing conventional Ravigneaux gear train. The kinematics, static torque, and power flow relations for all operation modes are analyzed in detail.
Fatigue Damage Evaluation of Turbine Generator Due to Multi-Mode Subsynchronous Oscillation
Authors: Liu Chao , Jiang Dongxiang
Published: March 2011

In recent years, Subsynchronous Resonance (SSR) and Subsynchronous Oscillation (SSO) are increasingly attracting more and more researchers’ interests in China. The network is encountering great changes and large-scale networks are increasingly implemented for long distance power transmission as well as various kinds of power electronic devices. Several SSO phenomena were monitored in a fossil-fired power plant in China in 2008. They were determined as complex factors’ co-activation between the network and the turbine generator. Multi-mode torsional vibration is one significant feature of torsional vibration caused by SSO. The paper simulates the multi-mode SSO based on the practical situation in China. The torsional vibration is studied to analyze the torsional vibration features under multimode SSO and the differences caused by different peak values and phases of electromagnetic torques. Based on some type of 600MW steam turbine generator, the fatigue damage of the shafts is studied.
A MINLP Model for Global Optimization of Plug-In Hybrid Vehicle Design and Allocation to Minimize Life Cycle Greenhouse Gas Emissions
Authors: Shiau Ching-Shin Norman , Michalek Jeremy J.
Published: March 2011

Plug-in hybrid electric vehicles (PHEVs) have potential to reduce greenhouse gas (GHG) emissions in the U.S. light-duty vehicle fleet. GHG emissions from PHEVs and other vehicles depend on both vehicle design and driver behavior. We pose a twice-differentiable, factorable mixed-integer nonlinear programming model utilizing vehicle physics simulation, battery degradation data, and U.S. driving data to determine optimal vehicle design and allocation for minimizing lifecycle greenhouse gas (GHG) emissions. The resulting nonconvex optimization problem is solved using a convexification-based branch-and-reduce algorithm, which achieves global solutions. In contrast, a randomized multistart approach with local search algorithms finds global solutions in 59% of trials for the two-vehicle case and 18% of trials for the three-vehicle case. Results indicate that minimum GHG emissions is achieved with a mix of PHEVs sized for around 35 miles of electric travel. Larger battery packs allow longer travel on electric power, but additional battery production and weight result in higher GHG emissions, unless significant grid decarbonization is achieved. PHEVs offer a nearly 50% reduction in life cycle GHG emissions relative to equivalent conventional vehicles and about 5% improvement over ordinary hybrid electric vehicles. Optimal allocation of different vehicles to different drivers turns out to be of second order importance for minimizing net life cycle GHGs.
A Hoop Method for Orientation Order Analysis of Spherical Mechanisms
Authors: Tipparthi Hemanth , Larochelle Pierre
Published: March 2011

In this paper we present a novel methodology for orientation order analysis of spherical RR dyads. The methodology is a spherical generalization of the recent works of Myszka, Murray, and Schmiedeler for assessing position order of planar RR dyads. The objective of the methodology is to determine if a prescribed fixed axis location for a spherical RR dyad will result in the dyad guiding a moving rigid-body through a set of finitely separated spherical orientations in the desired order (e.g. 1, 2, 3, 4, etc.). First, the prior works on the order analysis of planar RR dyads via the propeller method are briefly reviewed. Next, the planar propeller methodology of Myszka, Murray, and Schmiedeler is extended to yield a spherical hoop methodology. The result is a useful tool to determine if a given spherical RR dyad will guide a moving body through a set of prescribed orientations in the desired order. Finally, we demonstrate the utility of the hoop method for order analysis of spherical RR dyads in three case studies.
Case Study in Systematic Design Engineering: Automotive Oil Pump Redesign
Authors: Eder W. Ernst
Published: March 2011

Students learning design engineering at times need a good example of procedure for design engineering, both for novel problems and for redesign. The systematic heuristic-strategic use of a theory to guide the design process — Engineering Design Science — and the methodical design process followed in this case study is only necessary in limited situations. The full procedure should be learned, such that the student can select appropriate parts for other applications. Creativity is usually characterized by a wide search for solutions, especially those that are innovative. The search can be helped by this systematic and methodical approach. This case example is presented to show application of the recommended method for redesign, and the expected scope of the output, with emphasis on the stages of conceptualizing. The case follows a redesign problem of an automotive oil pump.
Robust Control for Coordinated Motion of Flexible Space Manipulator Based on the Augmentation Approach
Authors: Chen Zhiyong , Chen Li
Published: March 2011

In this paper, the coordinated control of a flexible space manipulator system with a front flexible link is discussed. With the assumed mode method and linear momentum conservation of the system, the dynamics of the manpulator is derived in Lagrangian formulation. By using the augmentation approach, a robust control scheme for the coordinated motion between the spacecraft’s attitude and arm’s joints of the flexible space manipulator with bounded external disturbances and uncertain parameters to track the desired trajectories in joint space is proposed. It is designed based on a priori knowledge about the uncertainty-bound and possesses the advantage that it can greatly reduce the calculation time needed by the adaptive or neural network control schemes. Simulation results show that the presented controller can stabilize the system to track the desired trajectories and keep the vibration amplitude of the flexible arm to be relatively low-level.
How Likely is the Variety of Singularities of a Serial Manipulator a Smooth Manifold?
Authors: Mu¨ller Andreas
Published: March 2011

It is commonly assumed that the singularities of serial manpulators constitute generically smooth manifolds. This assumption has not been proved yet, nor is there an established notion of of genericity. In this paper two different notions of generic properties of forward kinematic mappings are discussed. Serial manipulators are classified according to the type of end-effector motion and feasible manipulator geometries. A sufficient condition for that generically singularities form locally smooth manifolds is presented. This condition admits to separately treat the individual classes. As an example it is shown that the singularities of 3-DOF manipulators form generically smooth manifolds.
Investigations of PMN-PT Single Crystal Performance
Authors: DeGiorgi Virginia G. , Gorzkowski E. P. , Pan M.-J. , Qidwai M. A. , Wimmer Stephanie A.
Published: March 2011

Application of new materials, such as PMN-PT single crystals, requires a good understanding of basic material performance under both electrical and mechanical loading. Over the past 5 years the authors have used both computational and experimental techniques to examine the relationships between poling direction, crystal orientation, and electric field actuation. Experiments show mixed results indicating that the relationship between material orientation and loading is more complex than originally imagined. In some cases crack initiation and propagation perpendicular to the applied field was observed within a few thousand cycles but in other cases no failure was observed even after a few hundred thousand cycles despite crack growth in the presence of introduced defects. Computational effort quickly identified a gap between development of theoretical constitutive models that addressed domain switching based nonlinear behavior and what was available in workable form as part of commercial finite element codes. This led to the implementation of a macro-mechanical constitutive model which addresses domain switching, into a commercially available finite element code. The rate independent version has been used to investigate issues of electric field actuation and poling direction. Presented here are insights into the fracture and fatigue behavior of piezoelectric single crystals from both experimental and computational studies.
Damage Detection of Space Truss Using Second Order Polynomial Method With BFGS Quasi-Newton Optimization
Authors: Wong Chun Nam , Xiong Jingqi , Huang Hong-Zhong , Hu Tianyou
Published: March 2011

A second order damage detection method is developed by expanding the original eigenparameters using their sensitivity terms with the variations in the structural variants. This vibration-based polynomial method is generated from eigenvalue re-analysis in conjunction with the polynomial algorithm. By incorporating basic forms of the Lagrange factor functions, numerical eigenparameter functions are generalized to multi-variate polynomial interpolated forms. Second order sensitivity terms are computed by differentiating these multi-variate eigenparameter functions with respect to the structural variants. Convergence of different order algorithms are compared using finite element model of a four element cantilever beam structure under various damaged percentage cases. Moreover, finite element model of a four bay modular space truss is established. Damage detections from small to large percentages are carried out through numerical simulations on the space truss. Most of these cases converge efficiently toward the ultimate solutions within 1% termination level. Therefore the BFGS algorithm works well with the nonlinear multi-variate system equations. The algorithm operates robustly with limited number of d.o.f.s in the reduced order model and limited number of vibration modes in the full model.
A Unified Approach for Multi-Point Cartesian Compliance Control of Serial Manipulators
Authors: Pitakwatchara Phongsaen
Published: March 2011

This paper proposes a unified approach for controlling the Cartesian compliance of multiple points assigned along the linkage chains of the manipulator. The method applies two key frameworks. Task-priority based control is used to synergistically plan the tasks of the advanced manipulation according to their relative priority. Then, the impedance control scheme is employed for implementing the controller. Additionally, with the use of generalized inverse theory throughout the development, the method is capable of controlling the manipulator at the singularities seamlessly. This low-level control system may be integrated with the high-level manipulation planning algorithm, which generates the online dynamical tasks based on the desired behavior and the sensor information, to accomplish the demanding operation.
Enhanced Topographical Characterization of Sharp Step Edges With Simultaneous AFM Imaging and Force Spectroscopy
Authors: Solares Santiago D.
Published: March 2011

Topographical imaging with atomic force microscopy (AFM) has become an established method since its invention in 1986. However, there exist a variety of imaging artifacts that can distort the acquired images, especially when using sharp probes such as carbon nanotubes or nanowires. This paper briefly discusses common imaging artifacts occurring at sharp step edges and explores theoretically their mitigation with spectral and multi-frequency methods that can perform simultaneous topographical imaging and force spectroscopy. The work focuses on the spectral inversion method, which has been experimentally validated by others [Stark et al., Proc. Natl. Acad. Sci. USA 99, 8473–8478 (2002); Sahin et al., Nature Nanotech. 2, 507–514 (2007)], and on a recently proposed dual-frequency-modulation method, which has been demonstrated within computational simulations and is under experimental implementation in our laboratory [Solares & Chawla, Meas. Sci. & Technol. 19, No. 055502; Chawla & Solares, Meas. Sci. & Technol. 20, No. 015501].
Neural Network Bushing Model Development Using Simulation
Authors: Johrendt Jennifer L. , Frise Peter R.
Published: March 2011

Neural networks are computationally efficient mathematical models that can be used to model quantitative and qualitative data. A neural network can be created through training with known input and output load-deflection data such that it learns to generalize the material characteristics without over-predicting the training data and losing its ability to anticipate behavior outside the training set. The challenge in creating a neural network model of a rubber bushing in a virtual model of a prototype assembly, for instance, is the lack of a physical prototype assembly. This paper describes a method by which data can be measured from a virtual prototype and used to define an appropriate data acquisition for the physical bushing. Training data can then be acquired using these guidelines and used for neural network model development. Subsequently, the enhanced model can then be used in the virtual simulation environment to increase the accuracy of the simulation results.
Validation of Computational Fluid Structure Interaction Models for Shape Optimization Under Blast Impact
Authors: Tan Huade , Goetz John , Tovar Andre´s , Renaud John E.
Published: March 2011

A first order structural optimization problem is examined to evaluate the effects of structural geometry on blast energy transfer in a fully coupled fluid structure interaction problem. The fidelity of the fluid structure interaction simulation is shown to yield significant insights into the blast mitigation problem not captured in similar empirically based blast models. An emphasis is placed on the accuracy of simulating such fluid structure interactions and its implications on designing continuum level structures. Higher order design methodologies and algorithms are discussed for the application of such fully coupled simulations on vehicle level optimization problems.
Part Reliability Design of Air-Cooled Turbine Blade Under Thermal Stress-Dependent Strength Using Polynomial Method
Authors: Wong Chun Nam , Huang Hong-Zhong , Xiong Jingqi , Ling Daijun
Published: March 2011

In this paper, Lagrange factor polynomial method is developed to generate the stress-strength interference model with thermal stress-dependent strength. Accuracy of this method is investigated by an aeroengine air-cooled turbine blade. The computed reliability is quite high under several thermal stress modes. Then probability mean function estimated by this method has relatively low errors over most subintervals of the thermal stress dependent strength distribution. With this approach conditional thermal stress-dependent strength reliability of aeroengine structural systems can be established conveniently. Meanwhile the application range of the classical stress-strength interference model can be extended.
Investigation of the Influences of Micro Vibrational Stimuli and Hydrophilicity of a Scaffold on a Bovine Endothelial Cell Culture
Authors: Li Ching-Wen , Wang Gou-Jen
Published: March 2011

Both the hydrophilicity of the scaffold and applied sheer stress can influence the growth of cultured cells. In this study, the influences of applied shear stress and the hydrophilicity of the scaffold on the growth of bovine endothelial cells (BEC) were investigated. A piezoelectric micro vibrational stage was used to provide micro vibrational stimuli of different frequencies to generate various sheer stresses. 24-well, biodegradable lactide-co-glycolide (PLGA) scaffolds, and nanostructuresd PLGA scaffolds were used for the cell culturing. From the results of this study, it can be inferred that the vibration induced sheer stress can effectively enhance BEC growth as long as the corresponding sheer force is less than the adhesive force between a cell and the scaffold. It is also suggested that micro vibration stimulus may be a more cost and time effective solution than the nanostructured scaffold approach for the enhancement of BEC growth.
Evaluating the Structural Performance of Ship’s Rudder Coatings
Authors: Wimmer Stephanie A. , DeGiorgi Virginia G. , Lemieux Edward J.
Published: March 2011

Computational simulations are used in many disciplines to determine levels of stress and deformation in a structure for comparison with material allowable limits. In this work, use is made of a detailed 3D model of a typical ship’s rudder to evaluate the stress and deformation characteristics of the rudder structural components including the corrosion control coating applied to the rudder surface. Three commercially available coating materials were evaluated. These coating selections represent a range of material characteristics from high ductility polymer to glassy. Design condition hydrostatic loads were used in all evaluations. Stress and deformation patterns within the rudder structure are discussed. Differences between the structural performance of the coatings are highlighted.
The Effect of Module Motion on MEMS Crash Sensor Outputs During Vehicle Crash Events
Authors: Chen Wei
Published: March 2011

This paper investigates the effect of sensor module motion on the output and functionality of MEMS crash accelerometers. Short duration and high amplitude shock pulses generated by a crash event may excite a large vibration on sensor module and cause undesirable sensor output and system failure. A series of vibration and shock tests are carried out to characterize the dynamic response of four commercial crash satellite sensor modules in the sensitive axis of MEMS sensor. It is found that most modules have natural frequencies below 5 kHz and Q-factors are generally high. Due to very stiff PCB structure in this direction, the difference between PCB response and module response is very small. A single degree of freedom vibration model is used to simulate vibration on sensor module during crash event or shock test. The simulation data from this model is input to the MEMS sensor behavior model to simulate its output in vehicle crash tests. It is found that neglecting module effect on MEMS sensor output may lead to large discrepancy between sensor simulation results and sensor test data. It is also found that the peak acceleration output of MEMS sensor may be reduced by module vibration due to complex sensor design.