bluuebunny/crossref_metadata_2025 huggingface dataset:
An optimized Protocol for Human M2 Macrophages using M‐CSF and IL‐4/IL‐10/TGF‐β Yields a Dominant Immunosuppressive Phenotype
Authors: Mia S. , Warnecke A. , Zhang X.‐M. , Malmström V. , Harris R. A.
Published: February 2014

Monocytes are highly abundant circulatory effector cells and play a vital role in driving or resolving inflammatory processes depending on their activation phenotype. We investigated and compared a panel of polarization protocols of blood‐derived monocytes to achieve a stable, optimal and effective regimen for in vitro induction of immunosuppressive human macrophages, evaluating their surface receptor expression, cytokine profile, scavenging function and ability to suppress T‐cell proliferation. Importantly, we assessed the effect of copolarization or secondary pro‐inflammatory stimulation of a primary anti‐inflammatory activation phenotype. A combination of IL‐4/IL‐10/TGF‐β yielded a relatively stable and dominant immunosuppressive phenotype characterized by higher IL‐10 production and down‐regulated TNF‐α, IL‐6, CD86, CD274 and MHC II expression. Functionally, IL‐4/IL‐10/TGF‐β‐stimulated macrophages (M2) had a potent deactivating effect on a subsequent pro‐inflammatory LPS/IFNγ‐activated macrophage (M1) stimulation and significantly suppressed T‐cell proliferation. Monocytes derived from patients with chronic inflammatory diseases could be induced to be anti‐inflammatory using this protocol. Pre‐differentiation with GM‐CSF or M‐CSF was further demonstrated to enhance final M1/M2 activation status. Our findings indicate a robust polarization protocol for generation of specific immunosuppressive human monocyte‐derived macrophages.
Age‐dependent changes in stratum corneum barrier function
Authors: Boireau‐Adamezyk E. , Baillet‐Guffroy A. , Stamatas G. N.
Published: February 2014

Background/purpose

The Stratum Corneum (SC) barrier function mainly depends on the SC structure at the tissue level, its composition, and the organization of intercellular lipidic cement at the molecular level. The goal of this study was to assess the age‐dependent changes of the SC barrier function and the associated physiological parameters.

Methods

This study was conducted on 40 French women divided into four groups of age. Measurements were done on three sites: cheek, protected, and exposed arm sites. SC composition (water, lipid/protein ratio, cholesterol, and ceramides) was measured using Raman confocal microspectroscopy, skin surface hydration using skin conductance, and barrier function through transepidermal water loss (TEWL) measurements.

Results

Transepidermal water loss decreases slightly with age, which is partially explained by the age‐dependent increase in SC thickness. This decrease is faster for the face compared to both arm sites. The lipid to protein ratio and lipid compactness decrease significantly with age only for the arm sites. Water concentration profiles only decrease very close to the skin surface. At all ages tested, the SC on the cheek showed significantly higher TEWL, water and lipid content and less thickness compared to the arm sites. Comparison of the exposed to unexposed arm site showed difference only for the lipid compactness at the older group studied.

Conclusion

Skin aging, body site and environmental exposure can affect the SC barrier function, its structure, and its lipid content. The thickening of the SC with age compensates for the decrease of the quantity and ordering of the lipidic cement.
The presence of KIR2DS5 confers protection against adult immune thrombocytopenia
Authors: Seymour L. A. , Nourse J. P. , Crooks P. , Wockner L. , Bird R. , Tran H. , Gandhi M. K.
Published: February 2014

Immune thrombocytopenia (ITP) is an autoimmune disorder of unknown aetiology, characterised by an isolated low platelet count in the absence of other identifiable causes. Genes influencing activation of the immune system have been identified as influencing predisposition. Killer cell immunoglobulin‐like receptors (KIR) control T‐cell and natural killer (NK) cell function via inhibitory and activating signalling pathways. The inhibitory KIR2DL3, KIR3DL2 and KIR3DL1 are up‐regulated in the T‐cells of patients with ITP in remission relative to those with active disease, and an association of KIR2DS2 and KIR2DL2 with ITP has also been reported. No comprehensive KIR analysis in ITP has been reported. We performed genotyping of all currently known KIR genes using sequence specific primer polymerase chain reaction (SSP‐PCR) on a cohort of 83 adult patients with ITP (chronic/persistent or relapsed primary ITP identified by defined criteria) and 106 age matched healthy white volunteers. Non‐white patients were not included in the analysis. There was an over‐representation of KIR2DS3 (known to be in linkage disequilibrium with KIR2DS2 and 2DL2) and under‐representation of KIR2DS5 (also protective against other immune mediated disorders) in adult ITP [odds ratio (OR) = 0.16, confidence interval (CI) 0.08–0.32, P < 0.001]. By multivariable binary logistic regression to adjust for age, sex and the effects of other KIR genes, the presence of KIR2DS2/2DL2 with KIR2DS5 abrogated the risk of KIR2DS2/2DL2 and the protective benefit of KIR2DS5. Further studies are required to establish the mechanistic basis for these observations and their potential impact on ITP therapy.
A histone methyltransferase inhibits seed germination by increasing PIF1 mRNA expression in imbibed seeds
Authors: Lee Nayoung , Kang Hyojin , Lee Daeyoup , Choi Giltsu
Published: February 2014

Phytochrome‐interacting factor 1 (PIF1) inhibits light‐dependent seed germination. The specific function of PIF1 in seed germination is partly due to its high level of expression in imbibed seeds, but the associated regulatory factors have not been identified. Here we show that mutation of the early flowering in short days (EFS) gene, encoding an H3K4 and H3K36 methyltransferase, decreases the level of H3K36me2 and H3K36me3 but not H3K4me3 at the PIF1 locus, reduces the targeting of RNA polymerase II to the PIF1 locus, and reduces mRNA expression of PIF1 in imbibed seeds. Consistently, the efs mutant geminated even under the phyBoff condition, and had an expression profile of PIF1 target genes similar to that of the pif1 mutant. Introduction of an EFS transgene into the efs mutant restored the level of H3K36me2 and H3K36me3 at the PIF1 locus, the high‐level expression of PIF1 mRNA, the expression pattern of PIF1 target genes, and the light‐dependent germination of these seeds. Introduction of a PIF1 transgene into the efs mutant also restored the expression pattern of PIF1 target genes and light‐dependent germination in imbibed seeds, but did not restore the flowering phenotype. Taken together, our results indicate that EFS is necessary for high‐level expression of PIF1 mRNA in imbibed seeds.
SCARECROW, SCR‐LIKE 23 and SHORT‐ROOT control bundle sheath cell fate and function in Arabidopsis thaliana
Authors: Cui Hongchang , Kong Danyu , Liu Xiuwen , Hao Yueling
Published: February 2014

Bundle sheath (BS) cells form a single cell layer surrounding the vascular tissue in leaves. In C3 plants, photosynthesis occurs in both the BS and mesophyll cells, but the BS cells are the major sites of photosynthesis in C4 plants, whereas the mesophyll cells are only involved in CO2 fixation. Because C4 plants are more efficient photosynthetically, introduction of the C4 mechanism into C3 plants is considered a key strategy to improve crop yield. One prerequisite for such C3‐to‐C4 engineering is the ability to manipulate the number and physiology of the BS cells, but the molecular basis of BS cell‐fate specification remains unclear. Here we report that mutations in three GRAS family transcription factors, SHORT‐ROOT (SHR), SCARECROW (SCR) and SCARECROW‐LIKE 23 (SCL23), affect BS cell fate in Arabidopsis thaliana. SCR and SCL23 are expressed specifically in the BS cells and act redundantly in BS cell‐fate specification, but their expression pattern and function diverge at later stages of leaf development. Using ChIP–chip experiments and sugar assays, we show that SCR is primarily involved in sugar transport whereas SCL23 functions in mineral transport. SHR is also essential for BS cell‐fate specification, but it is expressed in the central vascular tissue. However, the SHR protein moves into the BS cells, where it directly regulates SCR and SCL23 expression. SHR, SCR and SCL23 homologs are present in many plant species, suggesting that this developmental pathway for BS cell‐fate specification is likely to be evolutionarily conserved.
Clustering of the K+ channel GORK of Arabidopsis parallels its gating by extracellular K+
Authors: Eisenach Cornelia , Papanatsiou Maria , Hillert Ellin‐Kristina , Blatt Michael R.
Published: February 2014

GORK is the only outward‐rectifying Kv‐like K+ channel expressed in guard cells. Its activity is tightly regulated to facilitate K+ efflux for stomatal closure and is elevated in ABA in parallel with suppression of the activity of the inward‐rectifying K+ channel KAT1. Whereas the population of KAT1 is subject to regulated traffic to and from the plasma membrane, nothing is known about GORK, its distribution and traffic in vivo. We have used transformations with fluorescently‐tagged GORK to explore its characteristics in tobacco epidermis and Arabidopsis guard cells. These studies showed that GORK assembles in puncta that reversibly dissociated as a function of the external K+ concentration. Puncta dissociation parallelled the gating dependence of GORK, the speed of response consistent with the rapidity of channel gating response to changes in the external ionic conditions. Dissociation was also suppressed by the K+ channel blocker Ba2+. By contrast, confocal and protein biochemical analysis failed to uncover substantial exo‐ and endocytotic traffic of the channel. Gating of GORK is displaced to more positive voltages with external K+, a characteristic that ensures the channel facilitates only K+ efflux regardless of the external cation concentration. GORK conductance is also enhanced by external K+ above 1 mm. We suggest that GORK clustering in puncta is related to its gating and conductance, and reflects associated conformational changes and (de)stabilisation of the channel protein, possibly as a platform for transmission and coordination of channel gating in response to external K+.
Amplification of ABA biosynthesis and signaling through a positive feedback mechanism in seeds
Authors: Nonogaki Mariko , Sall Khadidiatou , Nambara Eiji , Nonogaki Hiroyuki
Published: February 2014

Abscisic acid is an essential hormone for seed dormancy. Our previous study using the plant gene switch system, a chemically induced gene expression system, demonstrated that induction of 9‐cis‐epoxycarotenoid dioxygenase (NCED), a rate‐limiting ABA biosynthesis gene, was sufficient to suppress germination in imbibed Arabidopsis seeds. Here, we report development of an efficient experimental system that causes amplification of NCED expression during seed maturation. The system was created with a Triticum aestivum promoter containing ABA responsive elements (ABREs) and a Sorghum bicolor NCED to cause ABA‐stimulated ABA biosynthesis and signaling, through a positive feedback mechanism. The chimeric gene pABRE:NCED enhanced NCED and ABF (ABRE‐binding factor) expression in Arabidopsis Columbia‐0 seeds, which caused 9‐ to 73‐fold increases in ABA levels. The pABRE:NCED seeds exhibited unusually deep dormancy which lasted for more than 3 months. Interestingly, the amplified ABA pathways also caused enhanced expression of Arabidopsis NCED5, revealing the presence of positive feedback in the native system. These results demonstrated the robustness of positive feedback mechanisms and the significance of NCED expression, or single metabolic change, during seed maturation. The pABRE:NCED system provides an excellent experimental system producing dormant and non‐dormant seeds of the same maternal origin, which differ only in zygotic ABA. The pABRE:NCED seeds contain a GFP marker which enables seed sorting between transgenic and null segregants and are ideal for comparative analysis. In addition to its utility in basic research, the system can also be applied to prevention of pre‐harvest sprouting during crop production, and therefore contributes to translational biology.
Quality of functional haematopoietic stem/progenitor cells from cryopreserved human umbilical cord blood
Authors: Eom J.‐E. , Kim D. S. , Lee M. W. , Yu D.‐K. , Jin K. S. , Shin S. , Lee S. H. , Sung K. W. , Koo H. H. , Yoo K. H.
Published: February 2014

Background and Objectives

Transplantation of cryopreserved umbilical cord blood (UCB) can be used to treat a multitude of haematologic and immunological diseases. In this study, we examined the quality of UCB cryopreserved for 2 (group I), 4 (group II) and 6 (group III) years.

Methods

The following parameters and procedures were used to test individual units of cryopreserved UCB: the number of total nucleated cells (TNC), cell viability, CFU‐GM assay, T‐cell activation in vitro and haematopoietic stem cell engraftment in NOD/SCID mice in vivo.

Results

The TNC recovery rates for groups I, II and III were 106·2 ± 6·17%, 96·69 ± 6·39% and 100·38 ± 5·27%, respectively, and the mean percentages of viable cells after thawing were 86·88%, 86·38% and 87·43%. When TNC were plated at 5 × 103, the number of CFU‐GM was 13·6 (group I), 13·8 (group II), 14·2 (group III) and 14·7 (fresh UCB). We confirmed that the huCD4+ and huCD8+ T cells within cryopreserved UCB are functionally responsive by assessment of activated huCD25+ cells. Moreover, the percentage of huCD45+ cells in the bone marrow was 4·32 ± 1·29% (group I), 4·48 ± 1·11% (group II), 4·40% ± 1·12% (group III) and 4·50% ± 0·66% (fresh UCB), and that in the peripheral blood was 14·69 ± 3·08% (group I), 15·24 ± 4·05% (group II), 15·74 ± 3·43% (group III) and 17·48 ± 3·74% (fresh UCB) in NOD/SCID mice infused with isolated huCD34+ cells.

Conclusion

These results indicated that cryopreserved UCB units efficiently retrieve in functionally competent form and are suitable for transplantation.
Implementation and public acceptability: lessons from food irradiation and how they might apply to pathogen reduction in blood products
Authors: Heddle N. M. , Lane S. J. , Sholapur N. , Arnold E. , Newbold B. , Eyles J. , Webert K. E.
Published: February 2014

Background and Objectives

The issues around food irradiation (FI) have both similarities and differences to pathogen reduction (PR) in blood products. We performed a systematic search of the FI literature to identify lessons that could help to inform the implementation of pathogen reduction technology for blood products.

Methods

A comprehensive literature search was performed in EMBASE. MEDLINE, PSYCHINFO, CINAL and Physiological Abstracts for articles related to FI that met predefined eligibility criteria. A coding scheme was developed by the investigators, and relevant information from the articles was coded using NVivo 9. Reports for each code were generated and summarized.

Results

One thousand two hundred and sixty‐six articles were identified by the broad search, and 50 met the study eligibility criteria for inclusion. The implementation of FI was slow and has been met by significant controversy, sparked by concerns from the public and social groups about the acceptability of irradiated food. Numerous factors influenced public acceptability including: demographic factors; perceptions of safety and risk; endorsement of and trust in the FI industry and social institutions that serve as opinion leaders; knowledge and the provision of scientific information including benefits and cost; and the availability of choice.

Conclusion

There are a number of lessons from the FI literature that may be generalizable to the implementation of PR of blood products. Based on findings from this study, six recommendations are made to facilitate public implementation of this new technology.
Design of a Nonreacting Combustor Simulator With Swirl and Temperature Distortion With Experimental Validation
Authors: Hall Benjamin F. , Chana Kam S. , Povey Thomas
Published: February 2014

Nonuniform combustor outlet flows have been demonstrated to have significant impact on the first and second stage turbine aerothermal performance. Rich-burn combustors, which generally have pronounced temperature profiles and weak swirl profiles, primarily affect the heat load in the vane but both the heat load and aerodynamics of the rotor. Lean burn combustors, in contrast, generally have a strong swirl profile which has an additional significant impact on the vane aerodynamics which should be accounted for in the design process. There has been a move towards lean burn combustor designs to reduce NOx emissions. There is also increasing interest in fully integrated design processes which consider the impact of the combustor flow on the design of the high pressure vane and rotor aerodynamics and cooling. There are a number of current large research projects in scaled (low temperature and pressure) turbine facilities which aim to provide validation data and physical understanding to support this design philosophy. There is a small body of literature devoted to rich burn combustor simulator design but no open literature on the topic of lean burn simulator design. The particular problem is that in nonreacting, highly swirling and diffusing flows, vortex instability in the form of a precessing vortex core or vortex breakdown is unlikely to be well matched to the reacting case. In reacting combustors the flow is stabilized by heat release, but in low temperature simulators other methods for stabilizing the flow must be employed. Unsteady Reynolds-averaged Navier–Stokes and large eddy simulation have shown promise in modeling swirling flows with unstable features. These design issues form the subject of this paper.
An Experimental Study on Heat Transfer Surface Area of Wavy-Fin Heat Exchangers
Authors: Asadi Masoud , Xie Gongnan
Published: February 2014

Effects of wavy-fins surface area on thermal-hydraulic performance of a heat exchanger have been observed. First, a new method to calculate the heat transfer area of wavy-fin surfaces is introduced. The results show that the proposed method is accurate enough to be used in the analysis of heat exchanger performance. One of the important aspects of this method is that it is a direct method compared with the experimental method introduced by Kays and London, and thus might be a strong tool in the optimization of heat exchangers based on different objective functions. Effects of some nondimensional parameters, such as amplitude-to-wavelength ratio, fin space ratio, and channel cross-section ratio on the heat transfer characteristics and pressure drop are also investigated.
Flow in the Simplified Draft Tube of a Francis Turbine Operating at Partial Load—Part II: Control of the Vortex Rope
Authors: Foroutan Hosein , Yavuzkurt Savas
Published: February 2014

Numerical simulations and investigation of a method for controlling the vortex rope formation in draft tubes are carried out in this paper, which is the second part of a two-paper series. As shown in the companion paper, formation of the vortex rope is associated with a large stagnant region at the center of the draft tube. Therefore, it is concluded that a successful control technique should focus on the elimination of this region. In practice, this can be performed by axially injecting a small fraction (a few percent of the total flow rate) of water into the draft tube. Water jet is supplied from the high-pressure flow upstream of the turbine spiral case by a bypass line; thus, no extra pump is needed in this method. It is shown that this method is very effective in elimination of the stagnant region in a simplified draft tube operating at two part-load conditions, i.e., at 91% and 70% of the best efficiency point (BEP) flow rate. This results in improvement of the draft tube performance and reduction of hydraulic losses. The loss coefficient is reduced by as much as 50% for the case with 91% of BEP flow rate and 14% for the case with 70% of BEP flow rate. Unsteady, three-dimensional simulations show that the jet increases the axial momentum of flow at the center of the draft tube and decreases the wake of the crown cone and thereby decreases the shear at the interface of the stagnant region and high velocity outer flow, which ultimately results in elimination of the vortex rope. Furthermore, reduction (by about 1/3 in the case with 70% of BEP flow rate) of strong pressure fluctuations leads to reliable operation of the turbine.
Estimating Local Decision-Making Behavior in Complex Evolutionary Systems
Authors: Sha Zhenghui , Panchal Jitesh H.
Published: February 2014

Research in systems engineering and design is increasingly focused on complex sociotechnical systems whose structures are not directly controlled by the designers, but evolve endogenously as a result of decisions and behaviors of self-directed entities. Examples of such systems include smart electric grids, Internet, smart transportation networks, and open source product development communities. To influence the structure and performance of such systems, it is crucial to understand the local decisions that result in observed system structures. This paper presents three approaches to estimate the local behaviors and preferences in complex evolutionary systems, modeled as networks, from its structure at different time steps. The first approach is based on the generalized preferential attachment model of network evolution. In the second approach, statistical regression-based models are used to estimate the local decision-making behaviors from consecutive snapshots of the system structure. In the third approach, the entities are modeled as rational decision-making agents who make linking decisions based on the maximization of their payoffs. Within the decision-centric framework, the multinomial logit choice model is adopted to estimate the preferences of decision-making nodes. The approaches are illustrated and compared using an example of the autonomous system (AS) level Internet. The approaches are generally applicable to a variety of complex systems that can be modeled as networks. The insights gained are expected to direct researchers in choosing the most applicable estimation approach to get the node-level behaviors in the context of different scenarios.
A Performance Index for Planar Repetitive Workspace Robots
Authors: Seriani S. , Gallina P. , Gasparetto A.
Published: February 2014

When large surfaces need to be covered by a robotic system, the most common solution is to design or employ a robot with a comparably large workspace (WS), with high costs and high power requirements. In this paper, we propose a new methodology consisting in an efficient partitioning of the surface, in order to use robotic systems with a workspace of arbitrarily smaller size. These robots are called repetitive workspace robots (RWR). To support this method, we formally define a general index IRWR in order to evaluate the covering efficiency of the workspace. Three algorithms to compute the index are presented, the uniform expansion covering algorithm (UECA), the corrected inertial ellipsoid covering algorithm (CIECA), and the genetic covering algorithm (GCA). The GCA, which delivers a solution in the proximity of the global-best one, is used as a baseline for a comparison between the UECA and the CIECA. Eventually, we present the results of a performance analysis of the three algorithms in terms of computing time. The results show that the CIECA is the best algorithm for the evaluation of the IRWR, almost reaching the global-best solutions of the GCA. Finally, we illustrate a practical application with a comparison between two commercial industrial paint robots: the ABB™ IRB 550 and the CMA® Robotics GR 6100.
Closed-Form Solution for Constant-Orientation Workspace and Workspace-Based Design of Radially Symmetric Hexapod Robots
Authors: Agheli Mahdi , Nestinger Stephen S.
Published: February 2014

The workspace of hexapod robots is a key performance parameter which has attracted the attention of numerous researchers during the past decades. The selection of the hexapod parameters for a desired workspace generally employs the use of numerical methods. This paper presents a general methodology for solving the closed-form constant orientation workspace of radially symmetric hexapod robots. The closed-form solution facilitates hexapod robot design and minimizes numerical efforts with on-line determination of stability and workspace utilization. The methodology can be used for robots with nonsymmetric and nonidentical kinematic chains. In this paper, the methodology is used to derive the closed-form equations of the boundary of the constant-orientation workspace of axially symmetric hexapod robots. Several applications are provided to demonstrate the capability of the presented closed-form solution in design and optimization. An approach for workspace-based design optimization is presented using the provided analytical solution by applying an iterative optimization algorithm to the find optimized structural parameters and an optimized workspace.
Rigid Front Underride Protection Device (FUPD): Compatibility and Development via Optimization
Authors: MacDonald Todd , El-Gindy Moustafa , Ghantae Srikanth , Ramachandra Sarathy , Critchley David
Published: February 2014

Front underride involving tractor-trailers and small passenger vehicles remains a concern to those wishing to improve highway safety. Although a number of Front Underride Protection Device (FUPD) designs have been studied for effectiveness with respect to performance under crash scenarios, the development process of such devices has been seemingly restricted to a disconnected method. This is to say; in order to truly optimize an FUPD, all influencing factors should be studied together as a unit, while conducting intelligent parameter variation to improve performance. NCAC’s 2010 Toyota Yaris Finite Element model is subjected to multiple rigid bar crash testing in order to investigate compatibility with changing ground clearance and contact bar cross sectional height.

Three FUPDs are then modeled using topology and multi-objective parametric optimization including shape variation in conformity with ECE R93 static load standards. These guards are then subjected to dynamic testing versus the Yaris model.
Disappearance of Resonance Tongues
Authors: Ruelas Rocio E. , Rand Richard H.
Published: February 2014

We investigate a phenomenon observed in systems of the form dx/dt=a1tx+a2tydy/dt=a3tx+a4ty

where ait=Pi+εQicos2t

where Pi, Qi and ε are given constants, and where it is assumed that when ε = 0 this system exhibits a pair of linearly independent solutions of period 2π. Since the driver cos2t has period π, we have the ingredients for a 2:1 subharmonic resonance which typically results in a tongue of instability involving unbounded solutions when ε >0. We present conditions on the coefficients Pi, Qi such that the expected instability does not occur, i.e., the tongue of instability has disappeared.
The Application of Parametric Excitation in MEMS Gyroscopes
Authors: Gallacher Barry J. , Hu Zhongxu , Harish Kiran Mysore , Bowles Stephen , Grigg Harry
Published: February 2014

Parametric excitation, via electrostatic stiffness modulation, can be exploited in resonant MEMS gyroscopes. In the case of the Rate gyroscope, which is by far the most common type of MEMS gyro, parametric excitation may be used to amplify either the primary mode of the gyro or the response to the angular rate. Both approaches will be discussed. In the more complex mode of operation, known as “Rate Integrating” the output of the gyro is angle directly as opposed to angular velocity in the case of Rate gyro. In this rate integrating mode of operation parametric excitation does offer an effective energy control used to initiate, sustain the vibration and minimise damping perturbations.

Parametric amplification of the primary mode of the rate gyroscope is presented and supported with experimental results. In this implementation parametric excitation is combined with external harmonic forcing of the primary mode in order to reduce electrical feedthrough of the driving signal to the sense electrodes. A practical parametric excitation scheme implemented using Digital Signal Processing has been developed to enable either amplification of the primary mode of the gyroscope or amplification of the response to the applied angular velocity. Parametric amplification of the primary mode of the gyroscope is achieved by frequency tracking and regulation of the amplitudes of the harmonic forcing and parametric excitation to maintain a desired parametric gain by closed loop PID control. Stable parametric amplification of the primary mode by a factor of 20 is demonstrated experimentally. This has important benefits regarding the minimisation of electrical feedthrough of the drive signal to the sense electrodes of the secondary mode. By taking advantage of the phase dependence of parametric amplification and the orthogonality of the Coriolis force and quadrature forcing, the response to the applied angular velocity may be parametrically amplified by applying excitation of a particular phase directly to the sensing mode. The major advantage of parametric amplification applied to MEMs gyroscopes is that it can mechanically amplify the Coriolis response before being picked off electrically. This is particularly advantageous for sensors where electronic noise is the major noise contributor. In this case parametric amplification can significantly improve the signal to noise ratio of the secondary mode by an amount approximately equal to the parametric amplification. Preliminary rate table tests performed in open loop demonstrate a magnification of the signal to noise ratio of the secondary mode by a factor of 9.5.
An Envelope Approach to Time-Dependent Reliability Analysis for Mechanisms
Authors: Du Xiaoping
Published: February 2014

This work is concerned with the time-dependent mechanism reliability defined over a period of time where a certain motion output is required. An envelope approach is proposed to improve the accuracy of the time-dependent mechanism reliability analysis. The envelope function of the motion error over the time period is created. Since the envelope function is not explicitly related to time, the time-dependent problem is converted into a time-independent problem. Then the envelope function is approximated by piecewise hyper-planes. To find the expansion points of the hyper-planes, the approach linearizes the motion error at the means of random dimension variables, and this approximation is accurate because the tolerances or the variances of the dimension variables are small. Then the expansion points are found with the maximum probability density at the failure threshold. The time-dependent mechanism reliability is then estimated by a multivariable normal distribution function at the expansion points. As an example, analytical equations are derived for a four-bar function generating mechanism. The numerical example shows the significant accuracy improvement.
Effects of Added Mass on Lead-Zirconate-Titanate (PZT) Thin-Film Microactuators in Aqueous Environments
Authors: Luo Chuan , Yang Chen-Wei , Cao G. Z. , Shen I. Y.
Published: February 2014

In this paper, we conduct experimental and theoretical studies of a lead-zirconate-titanate (PZT) thin-film microactuator probe submerged in water. The microactuator consists of a base silicon diaphragm, a layer of bottom electrode, a layer of lead-zirconate-titanate (PZT) thin film, and a layer of top electrode. The diaphragm is anchored on a silicon substrate by etching the silicon substrate from the back to form a cavity under the diaphragm. The diaphragm along with part of its anchor is then diced off from the silicon substrate to form a PZT probe and subsequently packaged with parylene. The probe tip has dimensions of 1 mm × 1 mm × 0.4 mm, while the diaphragm has dimensions of 800 μm × 800 μm × 2 μm. In the experimental study, frequency response functions of actuator displacement are measured via a laser Doppler vibrometer and a spectrum analyzer. The measurements show that the first natural frequency of the microactuator reduces from 80 kHz in air to 20 kHz when the microactuator is submerged in water. A literature search indicates that the surrounding water induces significant added mass to the microactuator. Estimation of the added mass based on theories in fluid mechanics successfully reconcile the predicted frequency to the vicinity of 20 kHz confirming the effects of added mass.
Alternate Models of Replicator Dynamics
Authors: Wesson Elizabeth N. , Rand Richard H.
Published: February 2014

Models of evolutionary dynamics are often approached via the replicator equation, which in its standard form is given by x.i=xifix-ϕ,i = 1,…, n, where xi is the frequency, or relative abundance, of strategy i, fi is its fitness, and ϕ=∑i=1nxifi is the average fitness. A game-theoretic aspect is introduced to the model via the payoff matrix A, where Ai,j is the expected payoff of i vs. j, by taking fi(x) = (A·x)i. This model is based on the exponential model of population growth, ẋi = xifi, with ϕ introduced in order both to hold the total population constant and to model competition between strategies. We analyze the dynamics of analogous models for the replicator equation of the form x.i=gxifi-ϕ,

for selected growth functions g.
Multibody Analysis of a Human and Inverted-Pendulum Vehicle With and Without a Handle–Hand Constraint
Authors: Nakagawa Chihiro , Arakawa Shunsuke , Shintani Atsuhiko , Ito Tomohiro
Published: February 2014

An inverted-pendulum vehicle is controlled by the movement of the user’s gravity center; however, detailed dynamic interaction between the vehicle and a user has not been clarified. In a previous basic study, we investigated the relationships between the user and vehicle in the case that the handle and hand are not constrained [3]. In the present study, we constructed a model that constrains the hand and handle, and simulated the situation of the vehicle accelerating. The coupling model was built using multibody dynamics. The vehicle was expressed by three rigid bodies and a user by eight rigid bodies. In the numerical simulation, it was found that the vehicle accelerates more quickly when there is a constraint linking the handle and hand. This is because the force imparted by the user’s hand, resulting in inclination of the vehicle in the traveling direction, is easily transmitted to the vehicle through the handle.
Integration of Drill Torsional-Axial Coupling in Spindle-Vibratory Drilling Head Model for Stability Analysis
Authors: Mousavi Said , Gagnol Vincent , Ray Pascal
Published: February 2014

The drilling of deep holes with small diameters remains an unsatisfactory technology, since its productivity is rather limited. The main limit to an increase in productivity is directly related to the poor chip evacuation, which induces frequent tool breakage and poor surface quality. Retreat cycles and lubrication are common industrial solutions, but they induce productivity and environmental drawbacks. An alternative response to the chip evacuation problem is the use of a vibratory drilling head, which enables the chips to be fragmented thanks to the axial self-excited vibration. Contrary to conventional machining processes, axial drilling instability is sought, thanks to an adjustment of head design parameters and appropriate conditions of use. In this paper, self-vibratory cutting conditions are established through a specific stability lobes diagram. A dynamic high-speed spindle / drilling head / tool system model is elaborated on the basis of rotor dynamics predictions. The model-based tool tip FRF is integrated into an analytical stability approach. The torsional-axial coupling of the twist drill is investigated and consequences on drilling instability are established. Specific stability lobes are established and indicate modifications of self-excited operating zones. This approach allows refining the stability prediction of the global system during a drilling operation.
An Analysis of Engineers Information Seeking Activity
Authors: Cash Philip , Stanković Tino , Štorga Mario
Published: February 2014

Information seeking is an important part of the engineering design process. In this context the Internet has become a significant source of information, shaping the way engineers work and interact. Current work has focused on characterizing this activity in terms of total time allocated to different information sources or overall tasks, such as evaluating. However, these approaches do not give an understanding of how engineers information seeking affects their problem solving activity and ultimately their performance in the context of the design process. As such, a new approach is needed to decompose the complexity of information seeking activity in order to more effectively support the evolving needs of engineering designers and design researchers. This paper addresses these issues by using an experimental study and network visualization technique to analyze Internet based information seeking activity and its affect on engineers overall performance during the information seeking/feasibility stage of the design process. The study uses both final year trainee engineers and practicing engineers in order to more fully explore the different modes of information seeking activity. With the study complete, the visual network analysis is used to explore patterns of information seeking and other design activity. Based on the results, three clearly differentiated types of information seeking activity are identified and discussed.
Investigations on Concepts for Modularizing a Horizontal Axis Wind Turbine Blade
Authors: Saldanha Faber A. , Rao V. Venkateswara , Christopher J. , Adhikari Raviraja
Published: February 2014

The proposed investigation aims at evaluating concepts for modularizing horizontal axis wind turbine blades and also evaluate for their load carrying capability. This work begins with evaluation of a non-modularized blade to serve as a reference and for comparison with modularized blade. Static bending test is simulated as per IEC61400-23 standard. This work started with evaluating various modularization concepts for joining after identifying suitable location based on trade-off studies. These concepts are evaluated through a concept selection process involving various performance parameters as criteria. This work being exploratory in nature resulted in an evaluation procedure required for modularizing wind turbine blade.
Probabilistic Inverse Simulation and its Application in Vehicle Accident Reconstruction
Authors: Zhang Xiaoyun , Hu Zhen , Du Xiaoping
Published: February 2014

Inverse simulation is an inverse process of direct simulation. It determines unknown input variables of the direct simulation for a given set of simulation output variables. Uncertainties usually exist, making it difficult to solve inverse simulation problems. The objective of this research is to account for uncertainties in inverse simulation in order to produce high confidence in simulation results. The major approach is the use of the maximum likelihood methodology, which determines not only unknown deterministic input variables but also the realizations of random input variables. Both types of variables are solved on the condition that the joint probability density of all the random variables is maximum. The proposed methodology is applied to a traffic accident reconstruction problem where the simulation output (accident consequences) is known and the simulation input (velocities of the vehicle at the beginning of crash) is sought.
Numerical Modeling of Pit Growth in Microstructure
Authors: DeGiorgi Virginia G. , Kota Nithyanand , Lewis Alexis C. , Qidwai Siddiq M.
Published: February 2014

This work presents the numerical modeling of two-dimensional stable corrosion pit growth by solving the Laplace equation which defines the electric potential within the electrolyte. Microstructural features representative of a 316 stainless steel provides the matrix in which the pit grows. Real microstructural features are incorporated into the computational model. The objective is to determine the influence of the microstructure, specifically crystallographic orientation, on the shape of the pit as it grows over time. The high-resolution definition of the microstructure is obtained by the orientation image microscopy (OIM) technique and is incorporated into the finite element model through a grid-based interpolation functionality. The steel-electrolyte corrosion front movement is simulated with the help of the arbitrary Lagrangian-Eulerian (ALE) meshing technique. The front speed, or the material dissolution rate, is approximated with the use of a Butler-Volmer relationship that relates the dissolution current density to the applied overpotential. The results show that small fluctuations (5–10%) in corrosion potential due to the changing crystal orientation ahead of the corrosion front result in variations in pit shape similar to experimental observations reported in the literature.
Complex Modal Analysis of a Non-Modally Damped Continuous Beam
Authors: Xing Xing , Feeny Brian F.
Published: February 2014

This work represents an investigation of the complex modes of continuous vibration systems with nonmodal damping. As an example, a cantilevered beam with damping at the free end is studied. Traditional separation of variables for this problem leads to a differential eigenvalue problem which requires a numerical solution. In this paper, assumed modes are applied to discretize the eigenvalue problem in state-variable form, to then obtain estimates of the frequencies and modes. The finite-element method (FEM) is also utilized to get the mass, stiffness, and damping matrices and further to solve a state-variable eigenproblem. A comparison between the assumed-mode and finite-element eigenvalues and modal vectors shows that the methods produce consistent results. The comparison of the modes was done visually and also by using the modal assurance criterion (MAC) on the modal vectors. The assumed-mode method is then used to study the effects of the damping coefficient on mode shapes and modal damping.
Minimization of the Influence of Misalignments on EHD Lubrication in Face-Hobbed Spiral Bevel Gears
Authors: Simon Vilmos V.
Published: February 2014

In this study, an optimization methodology is proposed to systematically define optimal tooth modifications introduced by head-cutter geometry and machine tool settings to minimize the influence of misalignments on EHD lubrication characteristics in face-hobbed spiral bevel gears. The goal is to simultaneously maximize the EHD load carrying capacity of the oil film and to minimize power losses in the oil film when different misalignments are inherent in the gear pair. The proposed optimization procedure relies heavily on the EHD lubrication analysis developed by the author of this paper. The core algorithm of the proposed nonlinear programming procedure is based on a direct search method. Effectiveness of this optimization was demonstrated on a face-hobbed spiral bevel gear example. Drastic increase in the EHD load carrying capacity of the oil film and reduction in the power losses in the oil film were obtained.
Link-Based Performance Optimization of Spatial Mechanisms
Authors: Yihun Yimesker , Bosworth Ken , Perez-Gracia Alba
Published: February 2014

In the design of spatial linkages, the finite-position kinematics is fully specified by the position of the joints in space. However, most of the tasks have additional requirements regarding motion smoothness, obstacle avoidance, force transmission or physical dimensions. Many of these additional performance requirements are independent of the finite-position kinematic task and can be solved using link optimization for an already defined set of joints.

In this paper we develop a methodology to optimize spatial mechanisms after a first kinematic synthesis stage, by considering the links as anchored to sliding points of a given set of joint axes, which have to meet constraints including link dimension, restricted region of operation and force transmission. The optimization is performed using a hybrid algorithm, including a genetic algorithm (GA) and a gradient-based minimization solver.

The methodology has been applied to a spatial CRR-RRR, one-degree-of-freedom closed linkage. The additional requirements in this example are used to control the position and size of the mechanism, and for reducing friction loads at the joints.

The combination of the kinematic synthesis together with the link optimization developed in this paper allows interactive monitoring and control of the objectives and constraints, to yield practical solutions for realistic spatial mechanism design problems.
Real-Time Vehicle Parameters Estimation
Authors: Kolansky Jeremy , Sandu Corina , Botha Theunis , Els Schalk
Published: February 2014

Parameter estimation for vehicle systems is in general a challenging topic from both sensor instrumentation and modeling perspectives. Modeling vehicle systems is a rather complex process, especially considering the numerous unknown effects on the system such as, for example, aerodynamic effects, road grade and bank angles, roll and pitch kinematics, and suspension nonlinearities. This study develops a method that is able to estimate several vehicle parameters with high accuracy for regular driving behavior. The parameter estimations are performed using the polynomial chaos-based extended Kalman filter (gPC-EKF). This method is a computationally efficient, derivative free, iterative, nonlinear regression technique which is able to estimate multiple parameters in real time. The paper presents the results obtained for estimating the location of the CG of the vehicle in the horizontal plane, and the sprung mass of the vehicle using the proposed technique. Real test data have been used for validation purposes.
Assured Safety Drill With Bi-Stable Bit Retraction Mechanism
Authors: Loschak Paul M. , Xiao Kechao , Pei Hao , Kesner Samuel B. , Thomas Ajith J. , Walsh Conor J.
Published: February 2014

A handheld, portable cranial drilling tool for safely creating holes in the skull without damaging brain tissue is presented. Such a device is essential for neurosurgeons and mid-level practitioners treating patients with traumatic brain injury. A typical procedure creates a small hole for inserting sensors to monitor intra-cranial pressure measurements and/or removing excess fluid. Drilling holes in emergency settings with existing tools is difficult and dangerous due to the risk of a drill bit unintentionally plunging into brain tissue. Cranial perforators, which counter-bore holes and automatically stop upon skull penetration, do exist but are limited to large diameter hole size and an operating room environment. The tool presented here is compatible with a large range of bit diameters and provides safe, reliable access. This is accomplished through a dynamic bi-stable linkage that supports drilling when force is applied against the skull but retracts upon penetration when the reaction force is diminished. Retraction is achieved when centrifugal forces from rotating masses overpower the axial forces, thus changing the state of the bi-stable mechanism. Initial testing on ex-vivo animal structures has demonstrated that the device can withdraw the drill bit in sufficient time to eliminate the risk of soft tissue damage. Ease of use and portability of the device will enable its use in unregulated environments such as hospital emergency rooms and emergency disaster relief areas.