bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparative Study of Energy and Material Flow in Modulation-Assisted Machining and Conventional Machining
Authors: Yeung Ho , Guo Yang , Mann James B. , Compton W. Dale , Chandrasekar Srinivasan
Published: October 2014

A study has been made of deformation, forces and energy in modulation-assisted machining (MAM), wherein chip formation occurs in the presence of a controlled, low-frequency modulation superimposed on to the machining. A unique feature of the study is the use of high speed in situ imaging and image analysis to map material flow in the chip formation zone at high resolution; and simultaneous measurements of tool motions and forces, such that the instantaneous forces can be overlaid onto the chip formation process. The measurements show that the observed significant reductions in specific energy in MAM relative to conventional machining, when cutting ductile metals such as copper and Al 6061T6, are a consequence of chip formation with reduced strain levels in MAM. Additional insights into the chip formation are obtained by examining the effects of a chip aspect ratio parameter.
Fabrication of Continuously Varying Thickness Micro-Cantilever Using Bulk Lithography Process
Authors: Bhole Kiran , Ekshinge Sunil , Gandhi Prasanna
Published: October 2014

This paper presents fabrication of varying thickness polymer micro-cantilever using recently developed and characterized, single scan, three-dimensional (3D) micro-fabrication process termed as “bulk lithography”. The process allows fabrication of 3D microstructures that demonstrate continuous variation in the thickness direction as against the discrete variation provided by the normal microstereolithography (layer-by-layer) and other VLSI processes. The required depth variation is obtained during fabrication by allowing unconstrained depth photopolymerization and varying laser exposure while scanning. Towards goal to achieve the control over cured depth and smooth free surface (down facing surface), the process is characterized for cured depth and width under wide range of energy dose at different exposure duration. The depth characterization, represented earlier in a form of an empirical model, is used programmatically to impose any desired spatial intensity variation during scan. Additional width characterization, presented in this paper, is used to optimize the line spacing for achieving smooth unconstrained surface. Specific case of fabrication of tapered micro-cantilever is demonstrated with the proposed technique.
Vibrating Needle Cutting Force
Authors: Barnett Andrew C. , Wolkowicz Kelilah , Moore Jason Z.
Published: October 2014

Needles are one of most commonly used medical devices, used to deliver drugs, biopsy tissue, draw blood, conduct brachytherapy cancer treatment and many other procedures. Maintaining a low insertion force of the needle is important to the success of these procedures. Utilizing vibratory cutting reduces the insertion force, thus improving the outcome of the procedure. This paper describes the experimental setup utilized to test the effectiveness of axial vibration in reducing the insertion force into porcine skin across a range of frequencies, amplitudes and needle sizes. Experiments showed the addition of the vibration was able to reduce the insertion force by up to 35%. The minimum insertion force occurred at lower maximum vibratory insertion speeds for larger diameter needles.
Deformation Control Based on In-Situ Sensors for Mask Projection Based Stereolithography
Authors: Xu Kai , Chen Yong
Published: October 2014

Curl distortion is one of the main reasons for the part inaccuracy in the Mask Image Projection based Stereolithography (MIP-SL) process. During the building process, the photopolymerization of liquid resin leads to temperature increase. After cooling down, the cured layers will shrink while they are constrained by its supports or the previously built layers. Consequently, residue stresses exist in the built part and will lead to curl distortion after all the supports are removed. In this paper, we investigate the thermal effect in the building process by using an infrared (IR) camera as an in-situ temperature monitoring sensor. Test cases of cured layers with different shapes, sizes and layer thicknesses have been designed and tested. The experimental results show that the temperature increase of a cured layer is mainly related to its layer thickness, while its shapes and sizes have less effect. The temperature increase of a cured layer is also related to its building position in the Z axis. The calibrated temperature increases in the MIP-SL process can be incorporated in a Finite Element Analysis (FEA) model in order to simulate the curl distortion of a given computer-aided design model. Physical experiments of a simple test case have been built, measured, and compared with the FEA simulation result. A discussion of the curl distortion in the MIP-SL process including its prediction and compensation is given.
Towards Knowledge Based Process Planning Support for CAPP-4-SMEs: Problem Description, Relevant State of the Art and Proposed Approach
Authors: Miltner Franz , Vogel Tobias , Hemmje Matthias
Published: October 2014

Knowledge sharing approaches enable collaborative process-oriented planning in adaptive and highly dynamic, i.e., innovation and therefore change-driven, cross-organizational production environments. Externalization of knowledge as well as knowledge and process formalization is the key enabling factors for supporting collaborative production process planning. Beyond that SMEs request for a standardized production-planning oriented knowledge and feature representation. Semantic Web- and at the same time Cloud-based application s solutions which are based on process-driven knowledge representation methodologies such as WPIM can satisfy these needs, support intelligent collaboration, being able to cope with high change dynamics and therefore support boosting overall adaptiveness of production processes. Furthermore semantic knowledge representation and semantic querying add value to knowledge-based Computer-Aided Process Planning and, finally, pave the way towards automating planning, simulation and optimization.
Thermomechanical Investigation of Overhang Fabrications in Electron Beam Additive Manufacturing
Authors: Cheng Bo , Lu Ping , Chou Kevin
Published: October 2014

Electron beam additive manufacturing (EBAM) is one of powder-bed-fusion additive manufacturing processes that are capable of making full density metallic components. EBAM has a great potential in various high-value, small-batch productions in biomedical and aerospace industries. In EBAM, because a build part is immersed in the powder bed, ideally the process would not require support structures for overhang geometry. However, in practice, support structures are indeed needed for an overhang; without it, the overhang area will have defects such as warping, which is due to the complex thermomechanical process in EBAM. In this study, a thermomechanical finite element model has been developed to simulate temperature and stress fields when building a simple overhang in order to examine the root cause of overhang warping. It is found that the poor thermal conductivity of Ti-6Al-4V powder results in higher temperatures, also slower heat dissipation, in an overhang area, in EBAM builds. The retained higher temperatures in the area above the powder substrate result in higher residual stresses in an overhang area, and lower powder porosity may reduce the residual stresses associated with building an overhang.
AFM-Based Nanoscratching: A 3D Molecular Dynamics Simulation With Experimental Verification
Authors: Promyoo Rapeepan , El-Mounayri Hazim , Varahramyan Kody
Published: October 2014

In this paper, a developed three-dimensional model for AFM-based nanomachining is applied to study mechanical scratching at the nanoscale. The correlation between the scratching conditions, including applied force, scratching depth, and distant between any two scratched grooves, and the defect mechanism in the substrate/workpiece is investigated. The simulations of nanoscratching process are performed on different crystal orientations of single-crystal gold substrate, Au(100), Au(110), and Au(111). The material deformation and groove geometry are extracted from the final locations of atoms, which are displaced by the rigid indenter. The simulation also allows for the prediction of normal and friction forces at the interface between the indenter and substrate. An AFM is used to conduct actual scratching at the nanoscale, and provide measurements to which the MD simulation predictions are compared. The predicted forces obtained from MD simulation compares qualitatively with the experimental results.
Investigation of PZT/Si Wafer Micro Milling Using Diamond Coated Tool
Authors: Tai Tsen-Chen , Lu Ming-Chyuan , Wu Chia-Che , Chou Yen-Cheng , Tsai Yao-Yang
Published: October 2014

The cutting performance of the PZT/Si wafer micro milling was investigated by using the diamond coated micro end mill. At the same time, the cutting force and AE signals collected during cutting were also investigated to identify their capability of monitoring the surface condition and ductile/brittle cutting mode. To analyze the cutting performance of PZT thin film and corresponding signals, an experiment was conducted on a micro-machining equipment with resolution of 1 um. The PZT thin film with thickness of around 1 um was deposited on the Si wafer by a Sol-Gel method. During cutting, the AE signal was collected by an AE sensor clamped on the top of wafer, and the cutting force was collected by a Kistler 9256C dynamometer installed under a vacuum chuck. After the cutting, the finished surface was investigated by a white light interferometer system, and the chip was also investigated by a scanning electronic microscopic (SEM). The results show that the while light interferometer can be used to identify the cracked spot on the bottom of the machined surface. For the cutting mode analysis, the ductile mode cutting cannot be reached for the PZT thin film machining in this study. However, it can be obtained for Si wafer at the same cutting condition. Moreover, the RMS cutting force for PZT machining is higher than the Si wafer machining and its surface finish is not as good as in cutting the pure Si wafer. In analyzing the collected AE and cutting force signals, the AE signal, the time domain cutting force signals, and the RMS cutting force signals demonstrate their high correlation with the ductile/brittle cutting mode and surface condition.
Fixture Layout Optimization Based on Social Radiation Algorithm
Authors: Xing Yanfeng , Ni Jun , Lan Shuhuai
Published: October 2014

Sheet metal parts easily deformed during clamping and welding, and fixture layout design is very difficult because it takes a long time to calculate and read displacements of all nodes. This paper proposes a method to optimize fixture scheme by a social radiation algorithm (SRA). Firstly unfeasible candidate nodes are eliminated by some rules according to manufacturing experiences. Afterwards some feasible zones are optimized by SRA. Finally the best fixture layout is obtained through selecting the feasible nodes among the optimal zones. A case study of guiding gutter is used to illustrate the proposed method, and the results show that the social radiation algorithm has better efficiency and higher accuracy than the genetic algorithm.
Intelligent User Interface in Cloud Manufacturing
Authors: Ren Lei , Zhang Lin , Hou Baocun , Wu Qiong , Teng Dongxing
Published: October 2014

The idea of cloud manufacturing is gradually transforming the way enterprises do business in this age of globalization. The development of cloud manufacturing is closely linked to domain specific users in manufacturing industry. The huge amount of users with diverse roles and various requirements in manufacturing industry will face great challenges of cloud system usability problems. Thus user interface issues play important roles in this new area. Current research on cloud manufacturing pays more attention to internal cloud while makes light of external end-users’ usability, i.e. user interface issues. In this paper we discuss the key characteristics of Intelligent User Interface (IUI) for cloud manufacturing, i.e., naturality, smart mobility, self-configuration, and flexible customization. Further, a cloud-plus-IUI model for cloud end-users is presented. Then we discuss the enabling technologies, i.e., automatic configuration based on virtualization, context-aware adaption and recommendation, and multimodal interaction.
Automated High-Dynamic-Range Three-Dimensional Optical Metrology Technique
Authors: Ekstrand Laura , Zhang Song
Published: October 2014

Measuring three-dimensional (3D) surfaces with extremely high contrast (e.g., partially shiny surfaces) is extremely difficult with optical metrology methods. Conventional techniques, which involve measurement from multiple angles or camera aperture adjustments, pose issues for high accuracy measurement in the manufacturing industry because they are difficult to automate and often induce undesirable vibrations in the calibrated measurement system. This paper presents a framework for optically capturing high-contrast 3D surfaces via flexible exposure time variation. This technique leverages the binary defocusing technique that was recently developed at Iowa State University to allow digital fringe projection with a camera exposure time far shorter than the projector’s projection period. Since the camera exposure time can be rapidly adjusted in software, the proposed technique could be automated without mechanical adjustments to the measurement system. Moreover, the exposure times are sufficiently short as to be efficiently packed into a projection period, giving this technique the potential for high speed applications. Experimental results will be presented to demonstrate the success of the proposed method.
A Discussion on Removal Mechanisms in Grinding Polycrystalline Diamond
Authors: Schindler Florestan , Klocke Fritz , Brocker Richard , Mattfeld Patrick
Published: October 2014

In this paper, the removal mechanisms in grinding polycrystalline diamond (PCD) with vitrified bonded diamond grinding wheels are discussed fundamentally. After a short review about the history of diamond machining, the author summarizes the state of the art in PCD grinding and thus deduces gaps and a deficit in research. In order to analyze occurring removal mechanisms in PCD grinding, tool grinding tests were carried out. For the experimental investigations a conventional tool grinding machine has been modified in order to withstand process loads. Subsequent to the tests, the surface integrity of ground PCD inserts has been analyzed in detail for the first time. Therefore, focused ion beam (FIB) preparation, which has minimum invasive influence on the sub surface, was applied in order to get an insight into the substrate. Gained lamellae have been analyzed with transmission electron microscopy (TEM). The drawn conclusion questions solely ductile or brittle behavior as removal mechanisms. With reference to simulation researches about polishing diamond with diamond, alternative removal mechanisms should be regarded as well. Both, thermal and mechanical process loads might lead to thermo-physical and chemical effects on a microscopic scale which influences the material removal even in grinding.
Tool Wear Model for Double Face Grinding With Planetary Kinematics
Authors: Uhlmann Eckart , Kleinschnitker Michael , Hoghe Tom
Published: October 2014

Double face grinding with planetary kinematics is a process used to manufacture workpieces with plane parallel functional surfaces. In order to increase the economic efficiency of this process, it has to be continuously developed. Tool optimization offers a huge potential as the tools are exposed to particular loads, due to the kinematics of the process. To fulfill this task, it is necessary to analyze the chip removal mechanisms, the kinematical coherences and the related tool wear. The main goal of the presented work is the reduction of the tool wear.
Modeling of Melt-Pool Formation and Material Removal in Micro Electro-Discharge Machining
Authors: Mujumdar Soham S. , Curreli Davide , Kapoor Shiv G. , Ruzic David
Published: October 2014

This paper presents a μ – EDM melt-pool model to predict workpiece (anode) material removal from a single discharge μ – EDM process. To model the melt-pool heat transfer and fluid flow equations are solved in the domain containing dielectric and workpiece material. A level set method is used to identify solid and liquid fractions of the workpiece material when the material is molten by μ – EDM plasma heat flux. The plasma heat flux, plasma pressure and the radius of the plasma bubble have been estimated by a μ – EDM plasma model and serve as inputs to the melt-pool model to predict the volume of material removed from the surface of the workpiece. Experiments are carried out to study the effect of inter-electrode voltage and gap distance on the crater size. For inter-electrode voltage in the range of 100–150 V and gap distance of 0.5–2 μm, the model predicts crater diameter in the range of 150–165 μm and maximum crater depth of 25–35 μm for discharge duration of 5 μs. The crater sizes for most of experimental craters at higher gap distances show good agreement with the simulated crater shapes. However, at lower gaps, the model over-predicts the crater size.
Active Chatter Damping in Plunge Grinding Using Magnetic Actuators
Authors: Ahrens Markus , Fischer Ruben , Dagen Matthias , Denkena Berend , Ortmaier Tobias
Published: October 2014

In cylindrical plunge grinding with conventional grinding wheels, self-excited vibrations are one of the most limiting factors in terms of productivity and process stability. Initial vibration related to the dynamic behavior of the workpiece and machine copy on the grinding wheel, causing an increasing waviness due to uneven wear and therefore, an increasing vibration of the workpiece. These self-excited oscillations lead to many expensive true-running cycles in order to ensure high workpiece quality and process stability. In this context, we present an abrasion manipulation system for active vibration control using a self-built magnetic actuator to influence the tool wear and prevent the development of wheel-sided chatter. Estimation of the grinding wheel’s surface waviness has been achieved using a surface model, which parameters are estimated by a recursive-least-square-algorithm (rls), exclusively using data of workpiece movement. Using the estimated tool-surface-signal to predict forces onto the workpiece, it is possible to compensate them by the actuator and impend the development of waves on the wheel’s surface. The concept has been applied to a standardized plunge grinding process demonstrating successful chatter suppression at a former instable process.
Modeling and Compensation of Backlash and Harmonic Drive-Induced Errors in Robotic Manipulators
Authors: Sammons Patrick M. , Ma Le , Embry Kyle , Armstrong Levi H. , Bristow Douglas A. , Landers Robert G.
Published: October 2014

Harmonic drives, used widely in robot transmission systems, can induce significant periodic, joint-dependent position errors. Further, backlash in transmission systems, caused by wear or improper assembly, can considerably limit the overall repeatability, and therefore accuracy, of robotic manipulators. To measure the kinematic errors induced by both the harmonic drive and backlash, a laser tracker system, accurate to 10 μm at 20 m, is used to measure the end-effector position of a FANUC 200i LR Mate as its first joint is actuated randomly through ±130° (i.e., the range visible by the laser tracker). A joint-dependent model is then derived to account for the error seen in the measurements. Using a maximum likelihood estimator, the joint-dependent model coefficients and the amount of backlash are simultaneously identified. After backlash compensation is implemented, the maximum residual calculated between the nominal predicted position and the measured position of the end-effector, 0.2969 mm, is reduced by approximately 68%, to 0.0947 mm and the mean is reduced by 58% from 0.0631 to 0.0264 mm, after the error is modeled and compensation is implemented.
Investigations for Safe Grinding of Ti-6Al-4V Parts Produced by Direct Metal Laser Sintering (DMLS) Technology
Authors: Pavel Radu , Srivastava Anil K.
Published: October 2014

Direct Metal Laser Sintering (DMLS) is an additive manufacturing technology that can construct medium to small size parts very efficiently in comparison to traditional machining processes. The ability of this technology to grow complex parts made of high strength titanium- and nickel-based alloys led to increasing interest from aerospace, defense, and medical industries. Although the technology allows growing parts close to their final shape, the active surfaces still need a finishing operation such as grinding to meet the tight tolerances and surface finish requirements. Due to the novelty of the DMLS technology, and the relatively recent developments of titanium alloy powders, there is a need for testing and validating the capabilities of the components manufactured through a combination of DMLS and grinding processes. This paper presents the findings of an experimental study focused on the effect of various grinding conditions on the surface integrity of titanium alloy (Ti-6Al-4V) specimens produced using DMLS technology. The goal is to identify dressing and grinding conditions that would result in ground surfaces free of defects such as micro-cracks, discoloration of surfaces and/or burn marks due to high heat generated during grinding. The residual stresses were used to quantify the effect of the grinding conditions on the ground surfaces. These investigations were conducted on an instrumented CNC surface grinding machine, using a silicon-carbide grinding wheel and a water-based fluid. The X-ray diffraction method was used to measure the residual stresses. Two batches of specimens were manufactured for these tests. The growing strategy of the specimens and the presence of apparent defects in material structure are considered some of the main causes for the differences observed in the outcomes of the grinding trials. The results of these investigations support the need for continuing research in the additive manufacturing field to develop methods and technologies that will ensure a high level of consistency of the grown parts.
Multi-Objective Particle Swarm Optimization of Machining Parameters for End Milling Titanium Alloy Ti-6AL-4V
Authors: Ulutan Durul , Pleta Abram , Mears Laine
Published: October 2014

Titanium alloy Ti-6Al-4V is a material with superior properties such as high mechanical strength, corrosion and creep resistance, and high strength-to-weight ratio, which make it an attractive material for various industries such as automotive, aerospace, power generation, and biomedical industries. However, these superior properties as well as its low thermal conductivity and chemical reactivity make it a challenge to machine Ti-6Al-4V at optimal conditions. In order to overcome this challenge, researchers constantly develop new tools and new techniques, but the extent of machining rates that can be used efficiently with those tools and techniques are usually not clear. Considering only one variable in the process and optimizing according to that variable is not sufficient because of the interactions between parameters. Also, selecting one objective function from a pool of many is not beneficial since those objectives are in conflict with one another. Therefore, this study proposes the use of a combined optimization algorithm in order to account for three major variables in end milling of Ti-6Al-4V: cutting speed, feed, and depth of cut. These variables are optimized for multiple objectives. Although it is possible to optimize the process for many different objectives, some of them are heavily correlated to each other, hence two objectives representing machinability and efficiency are selected: tool flank wear and material removal rate. The study aims to establish an optimal Pareto front of machining parameters that would optimize the conflicting outputs of the process, utilizing the multi-objective particle swarm optimization technique.
Processing of Porous Zirconium Tungstate and Their Thermomechanical Properties
Authors: Wang Mingang , Do Truong , Kwon Patrick
Published: October 2014

This paper explores a new processing method to fabricate porous zirconium tungstate (ZrW2O8 or ZT) with the porosity content up to 40% in volume. The method uses spherical graphite powders that are mechanically stable, allowing us to compact with ceramic powders in dry condition. Thus, the ceramic powders mixed with spherical graphite powders can be compacted and sintered to a near full density. During sintering, the graphite powders burn out without damaging the powder compact due to their inherent near-zero thermal expansion. The processing route discussed in this paper is applicable to all oxide ceramics where the sintering can take place in air and above 700°C to dissociate the graphite. In this paper, we have applied this processing technique to fabricate porous ZrW2O8. Many porous ZrW2O8 with a range of porosity levels were fabricated and tested for their theromomechanical properties including elastic modulus (E) and coefficient of thermal expansion (CTE). The experimentally determined properties were compared with the predictions based on the micromechanical Mori-Tanaka scheme.
Effect of EAM Pulsed Current on 1450 MPA Martensitic Steel
Authors: Lobdell Megan A. , Roth John T. , Nikhare Chetan P. , Parsons Dennie , Yang Dae-Ho , Lee Hyun-Woo , Hong Sung-Tae
Published: October 2014

Martensitic steel is often used to fabricate parts that require high tensile strength. However, this quality, and the material’s low ductility, requires manufacturing equipment with higher tonnage capacity. This paper explores a potential way to reduce the tonnage requirement by temporarily reducing the steel’s required flow stress. Previous studies with other metals have shown that using a pulsed electric current will provide lower strength, as well as, an increase in ductility, without the sensitivity to temperature that heat treating has. This project investigates how martensitic steel reacts to pulsing electric current in terms of the tensile strength and elongation. The project consists of two studies. First, where the parameters considered were current density (CD), pulse duration (PD), pulse period (PP), and pressurized air (PA). Second is a series of tests where current duration was based off the material’s strength. The results from the first study show that the electricity can increase the material’s achievable elongation; the second study achieved reducing and limiting the material’s strength.
A Parametric Study on Laser Welding of Magnesium Alloy AZ31 by a Fiber Laser
Authors: Bailey Neil S. , Tan Wenda , Shin Yung C.
Published: October 2014

Laser welding of wrought magnesium alloy has been investigated through experimentation and simulation. Laser butt welds and laser lap welds were performed on 2.0 mm thick magnesium alloy AZ31 plates using a 1 kW fiber laser and shielded with argon gas. The effects of laser power and welding speed on weld geometry and microstructure were investigated. Through experimentation, the ranges of operating parameters for laser power and welding speed which resulted in viable, defect-free welds were found and reported. Simulations were carried out to predict the weld pool geometry and resultant microstructure and are shown to be in good agreement with experimental results.
Enhancement of Tribological Performance via Innovative Tooling Design for Extrusion Processes
Authors: Lowrie James B. , Ngaile Gracious
Published: October 2014

Due to the expense and negative environmental impact of commonly used conversion coating type lubricants a new method for reducing the friction in the extrusion process is desired. This paper investigates the possibility of modifying the die set to better the tribological conditions and reduce friction in the extrusion process. A novel design of extrusion tooling is proposed, in which the die set is segmented into three separate pieces, a punch, a wall die, and a bottom die. Additionally, the wall die is given the freedom to move along the axis of the punch and a high pressure lubricant is supplied to the interface between the wall and bottom dies. Preliminary tests of the segmented tooling show that, if the tribological conditions are severe enough, the forming load will decrease in comparison to a conventional extrusion system.
Fatigue Evaluation of 8630 Cast Steel Subjected to Post-Weld Heat Treatment and Stress Relieving
Authors: Shirazi Alireza , Ragai Ihab
Published: October 2014

The effect of post weld heat treating and stress relieving on the fatigue strength of AISI 8630 cast steel, weld repaired with different filler materials, is the primary objective of the study. To determine the material properties, experiments included monotonic tensile tests, load-controlled fatigue tests as well as hardness tests. Moreover, specimens were micro-etched to examine the morphology of the fracture surface.

The results of the fatigue tests are presented in the form of S-N charts. The test findings are then employed in a generalized numerical solution to predict the fatigue behavior of similar components.

Finite element models are used to calculate stresses in tested samples, stress concentrations, and in fatigue life comparisons. Stress-life predictions were performed using the modified Goodman criterion to account for the mean stress effects caused by the stress ratio R = 0.1 loading. Predictions based off of finite element analysis and analytical solution for fatigue life provided reasonable estimates which are confirmed by the experimental results.
Numerical Investigation of Two-Dimensional Thermally Assisted Ductile Regime Milling of Brittle Materials
Authors: Ma Jianfeng , Ge Xianchen , Lei Shuting
Published: October 2014

This study investigates the effects of different variables (preheating temperature, edge radius, and rake angle) on ductile regime milling of a bioceramic material known as nanohydroxyapatite (nano-HAP) using numerical simulation. AdvantEdge FEM Version 6.1 is used to conduct the simulation of 2D milling mimicked by orthogonal machining with varying uncut chip thickness. Thermal boundary conditions are specified to approximate laser preheating of the work material. Based on the pressure-based criterion for ductile regime machining, the dependence of critical depth of cut on cutting conditions is investigated using Tecplot 360. It is found that as uncut chip thickness decreases, the critical depth of cut decreases. In addition, the critical depth of cut increases as the negativity of rake angle and/or preheating temperature increase.
Modeling and Simulation of Flexible Needle Insertion Into Soft Tissue Using Modified Local Constraint Method
Authors: Lei Yong , Lian Bin
Published: October 2014

This paper presents a new simulation model for flexible needle insertion into soft tissue using modified local constraint method. In this work, we assume deformation of the needle is relatively small, therefore, the soft tissue deformation in the radial direction is far less than it is in the axial direction. Under the assumptions above, the spring model in the radial direction of the needle is established and applied in the puncture procedure to obtain the equilibrium position of the needle-tissue system. The FEM model for the simulation includes three iterative steps: 1. Distribute the axial force on the needle into tissue nodes, and add radial constraint on tissue nodes that are connected with needle’s shaft, then calculate the whole displacement of the tissue nodes; 2. Based on the whole displacement of all nodal points and the effective stiffness matrix, we get the radial force on the tissue, then we use the spring model in the radial direction to get the equilibrium position; 3. Compound the radial and axial force on the tissue nodal points to obtain the actual displacement. Simulation results are presented and discussed.
Identification of Process Damping Coefficient Based on Material Constitutive Property
Authors: Jin Xiaoliang
Published: October 2014

The contact between the tool flank wear land and wavy surface of workpiece causes energy dissipation which influences the tool vibration and chatter stability during a dynamic machining process. The process damping coefficient is affected by cutting conditions and constitutive property of workpiece material. This paper presents a finite element model of dynamic orthogonal cutting process with tool round edge and flank wear land. The process damping coefficient is identified based on the energy dissipation principle. The simulated results are experimentally validated.
Experimental and Numerical Analysis of Laser Peen Forming Mechanisms of Sheet Metal
Authors: Ding Hua , Shen Ninggang , Li Keqin , Bo Wu , Pence Chelsey N. , Ding Hongtao
Published: October 2014

Laser peen forming (LPF) is a novel non-contact sheet metal forming process without detrimental thermal defects. High pressure shock waves induced by a focused laser pulse are applied on the workpiece surface to generate deformations. In this study, the deformation mechanisms induced by LPF are experimentally and numerically investigated under different experimental conditions. Experiments have shown that when keeping laser parameters constant, deformation mechanisms vary depending on the sample thickness. The results show that aluminum sheet samples of 0.25 mm in thickness bend concavely for pulse energy ranging from 0.2 to 0.5 J, while 1.75 mm aluminum sheets bend convexly under the same conditions. There is a transition thickness threshold of sheet metal at which the deformation mechanism changes from concave to convex with the increase of the sample thickness with certain levels of laser parameter. This transition thickness threshold is determined to be around 0.7–0.88mm with the studied process parameters. Experiments also show that as the pulse energy increases, the transition thickness of the bending deformation mechanism increases slightly. Under the concave deformation mechanism, the workpiece is more sensitive to pulse energy, while pulse energy is not a critical factor in the convex mechanism. A finite element analysis (FEA) is performed to simulate the LPF deformation process with different specimen thicknesses and loading conditions. The simulation results agreed well with experimental results.
Incipient Plastic Strain Fields in Material Removal Processes
Authors: Du F. , Moreno C. , Wang Z. , Saldana C.
Published: October 2014

Knowledge of the plasticity associated with the incipient stage of chip formation is important for understanding the flow field underlying transient material removal processes. The transition from an incipient state of strain to steady-state was investigated in chip formation of copper. Characterization of the flow field was made by image correlation, hardness mapping and microstructure measurement. A framework for describing the incipient straining length in chip formation as a function of process parameters was established and explained by effects of the deformation on shear plane morphology. The present results are potentially useful for enabling better informed design of processing configurations wherein transient flow fields contribute significantly to the overall deformation process, such as in grain refinement methods for bulk materials and micro-mechanical surface texturing methods based on machining.
Determination of thin film coefficient of thermal expansion and residual strain from freestanding fixed–fixed beams
Authors: Pocratsky Ryan M. , de Boer Maarten P.
Published: October 2014

Coefficient of thermal expansion (CTE) is an important thin film property that is typically measured using multiple whole wafers. Here, the authors show how CTE can be locally extracted on a single substrate using out-of-plane deflection measurements of freestanding fixed–fixed beams versus temperature. Residual strain information is simultaneously extracted. Results for aluminum/0.5% copper thin film CTE, 37.4 ppm/ °C, and tensile residual strain, −161 με, are in good agreement with previously published values.
Effects of MoS2 thickness and air humidity on transport characteristics of plasma-doped MoS2 field-effect transistors
Authors: Chen Mikai , Wi Sungjin , Nam Hongsuk , Priessnitz Greg , Liang Xiaogan
Published: October 2014

The authors present a study on transfer characteristics of plasma-doped MoS2 transistors with various MoS2 thicknesses and those acquired under different air humidity conditions. The MoS2 thickness-dependent characterization implies that plasma-assisted doping processes induce p-doping to multilayer MoS2 channels through a surface-charge-transferlike mechanism and the effective space-charge layer thickness is estimated to be ∼22 nm. The humidity-dependent characterization shows that plasma-doped MoS2 transistors exhibit a much more prominent dependence of the transfer characteristics on humidity in comparison with pristine MoS2-based transistors. This is attributed to the plasma-induced dangling bonds or absorbate centers on MoS2 surfaces, which can enhance the absorption of water molecules and result in additional p-doping to MoS2 transistors. This work advances the understanding of the effects of plasma doping processes on the electronic properties of MoS2 and provides important technical insights for making MoS2-based gas and chemical sensors.
Inelastic electron tunneling spectroscopy for molecular detection
Authors: Zadeh Yasaman Hamidi , Durrani Zahid A. K.
Published: October 2014

Inelastic electron tunneling spectroscopy (IETS) [R. C. Jaklevic and J. Lambe, Phys. Rev. Lett. 17, 1139 (1966); R. G. Keil et al., Appl. Spectrosc. 30, 1 (1976); K. W. Hipps and U. Mazur, J. Phys. Chem. 97, 7803 (1993); U. Mazur et al., Anal. Chem. 64, 1845 (1992); P. K. Hansma, Tunneling Spectroscopy (Plenum, New York, 1982)] measurements are performed on Si nanowire (NW)/SiO2/Al NW tunnel junctions. The tunnel junction area is ∼50 × 120 nm and tunneling occurs across a 10 nm thick SiO2 layer. IETS measurements are performed at 300 K for ammonium hydroxide (NH4OH), acetic acid (CH3COOH), and propionic acid (C3H6O2) molecules. The I–V, dI/dV–V, and d2I/dV2–V characteristics of the tunnel junction are measured before and after the adsorption of molecules on the junction using vapor treatment or immersion. Peaks can be observed in the d2I/dV2–V characteristics in all the cases following molecules adsorption. These peaks may be attributed to vibrational modes of N–H and C–H bonds.
Taking the measure of change
Authors: Collen Ben , Nicholson Emily
Published: October 2014

Predictive models of biodiversity change are required to inform conservation policy decisions
Draft Genome Sequences of Brucella suis Biovar 4 Strain NCTC 10385, Brucella ceti Strain NCTC 12891
T
, Brucella inopinata Strain CAMP 6436
T
, and Brucella neotomae Strain ATCC 23459
T
Authors: Wahab Tara , Ferrari Sevinc , Lindberg Martina , Bäckman Stina , Kaden Rene
Published: October 2014

With the aim of developing quantitative PCR methods for the detection and differentiation of
Brucella
species, the genomes of
Brucella ceti
,
Brucella inopinata
,
Brucella netotomae
, and
Brucella suis
biovar 4 were sequenced and analyzed.
Complete Genome Sequence of Equid Herpesvirus 3
Authors: Sijmons Steven , Vissani Aldana , Tordoya Maria Silva , Muylkens Benoît , Thiry Etienne , Maes Piet , Matthijnssens Jelle , Barrandeguy Maria , Van Ranst Marc
Published: October 2014

Equid herpesvirus 3 (EHV-3) is a member of the subfamily
Alphaherpesvirinae
that causes equine coital exanthema. Here, we report the first complete genome sequence of EHV-3. The 151,601-nt genome encodes 76 distinct genes like other equine alphaherpesviruses, but genetically, EHV-3 is significantly more divergent.
Draft Genome Sequence of Polychlorinated Biphenyl-Dechlorinating Dehalococcoides mccartyi Strain SG1, Which Carries a Circular Putative Plasmid
Authors: Wang Shanquan , Chng Kern Rei , Wu Chen , Wilm Andreas , Nagarajan Niranjan , He Jianzhong
Published: October 2014

Dehalococcoides mccartyi
strain SG1, isolated from digester sludge, dechlorinates polychlorinated biphenyls (PCBs) to lower congeners. Here we report the draft genome sequence of SG1, which carries a 22.65 kbp circular putative plasmid.
Draft Genome Sequences of Campylobacter fetus subsp.
venerealis
bv. venerealis Strain B6 and bv. intermedius Strain 642-21
Authors: Barrero Roberto A. , Moolhuijzen Paula , Indjein Léa , Venus Bronwyn , Keeble-Gagnère Gabriel , Power John , Bellgard Matthew I. , Lew-Tabor Ala E.
Published: October 2014

Campylobacter fetus
subsp.
venerealis
is an important venereal pathogen. We sequenced the genomes of
Campylobacter fetus
subsp.
venerealis
bv. venerealis strain B6 and bv. intermedius strain 642-21. The genetic variability of these Australian strains will facilitate the study of mechanisms of geographical adaptation of these pathogens that impact livestock.
Draft Genome Assembly of Pseudomonas aeruginosa Quality Control Reference Strain Boston 41501
Authors: Minogue T. D. , Daligault H. E. , Davenport K. W. , Broomall S. M. , Bruce D. C. , Chain P. S. , Coyne S. R. , Gibbons H. S. , Jaissle J. , Chertkov O. , Freitas T. , Rosenzweig C. N. , Xu Y. , Johnson S. L.
Published: October 2014

We present the scaffolded genome assembly of
Pseudomonas aeruginosa
Boston 41501, now publicly available in GenBank (JOVK00000000) in 10 contigs placed into a single scaffold. The 6.82-Mbp genome contains 66.1% G+C content and 6,295 coding sequences, including type 4 pilus and type 3 secretion system production genes.
Genome Sequence of Lactococcus lactis subsp.
lactis
NCDO 2118, a GABA-Producing Strain
Authors: Oliveira Letícia C. , Saraiva Tessália D. L. , Soares Siomar C. , Ramos Rommel T. J. , Sá Pablo H. C. G. , Carneiro Adriana R. , Miranda Fábio , Freire Matheus , Renan Wendel , Júnior Alberto F. O. , Santos Anderson R. , Pinto Anne C. , Souza Bianca M. , Castro Camila P. , Diniz Carlos A. A. , Rocha Clarissa S. , Mariano Diego C. B. , de Aguiar Edgar L. , Folador Edson L. , Barbosa Eudes G. V. , Aburjaile Flavia F. , Gonçalves Lucas A. , Guimarães Luís C. , Azevedo Marcela , Agresti Pamela C. M. , Silva Renata F. , Tiwari Sandeep , Almeida Sintia S. , Hassan Syed S. , Pereira Vanessa B. , Abreu Vinicius A. C. , Pereira Ulisses P. , Dorella Fernanda A. , Carvalho Alex F. , Pereira Felipe L. , Leal Carlos A. G. , Figueiredo Henrique C. P. , Silva Artur , Miyoshi Anderson , Azevedo Vasco
Published: October 2014

Lactococcus lactis
subsp.
lactis
NCDO 2118 is a nondairy lactic acid bacterium, a xylose fermenter, and a gamma-aminobutyric acid (GABA) producer isolated from frozen peas. Here, we report the complete genome sequence of
L. lactis
NCDO 2118, a strain with probiotic potential activity.
Draft Genome Sequences of
Devosia
sp. Strain 17-2-E-8 and Devosia riboflavina Strain IFO13584
Authors: Hassan Yousef I. , Lepp Dion , He Jianwei , Zhou Ting
Published: October 2014

Here we report the draft genome of
Devosia
sp. strain 17-2-E-8, isolated from Ontario agricultural soil (Canada) with promising deoxynivalenol biotransformation capabilities. In addition, we report the draft genome of
Devosia riboflavina
strain IFO13584, used as a control strain in our studies aimed at highlighting unique gene clusters involved in deoxynivalenol epimerization.
High-Quality Draft Genome Sequence of
Pseudomonas
sp. BRG100, a Strain with Bioherbicidal Properties against
Setaria viridis
(Green Foxtail) and Other Pests of Agricultural Significance
Authors: Dumonceaux Tim J. , Town Jennifer , Links Matthew G. , Boyetchko Sue
Published: October 2014

Pseudomonas
sp. BRG100 inhibits the growth of certain agricultural pests and is a potentially useful biopesticide for weeds and plant diseases. We have sequenced the 6.25-Mbp genome of this strain and assembled it into 4 scaffolds. Genome sequence comparisons revealed that this strain may represent a novel species of
Pseudomonas
.
Acute disseminated encephalomyelitis (ADEM) following a H3N3 parainfluenza virus infection in a pregnant asthmatic woman with respiratory failure
Authors: Zeb Qaiser , Alegria Ana
Published: October 2014

This case report relates to a 31-year-old pregnant woman, asthmatic, admitted to the intensive care unit with respiratory failure, secondary to a viral community-acquired pneumonia. A type 3 (H3N3) parainfluenza virus RNA was isolated in her throat swab. The patient developed neurological symptoms (behavioural changes, irritability, agitation and impaired consciousness) while being weaned off sedation and ventilatory support. Cerebrospinal fluid was clear with an opening pressure of 26 cm H2O. Brain MRI showed features compatible with acute disseminated encephalomyelitis. Immune screen and EEG were normal. She was treated with intravenous methylprednisolone followed by oral prednisolone. The patient made an almost full neurological recovery within 4 weeks after starting on steroids. The patient delivered a healthy baby at 38 weeks gestation. This case highlights the importance to keep in mind rare conditions that need early recognition and prompt treatment. Brain MRI is the key to early diagnosis and treatment.
Habitual alcohol consumption associated with reduced semen quality and changes in reproductive hormones; a cross-sectional study among 1221 young Danish men
Authors: Jensen Tina Kold , Gottschau Mads , Madsen Jens Otto Broby , Andersson Anne-Maria , Lassen Tina Harmer , Skakkebæk Niels E , Swan Shanna H , Priskorn Lærke , Juul Anders , Jørgensen Niels
Published: October 2014

Objective

Study associations between three measures of alcohol consumption (recent, typical/habitual, binging), semen quality and serum reproductive hormones.

Design

Cross-sectional population based study.

Setting and participants

1221 young Danish men, aged 18–28 years were recruited when they attended a compulsory medical examination to determine their fitness for military service from 2008 to 2012. Total alcohol consumption: (1) in the week preceding (habitual/typical) the visit (recent alcohol intake), (2) in a typical week and (3) frequency of ‘binge drinking’ (consuming more than 5 units/day)) in the past 30 days was estimated.

Main outcome measures

Semen quality (volume, sperm concentration, total sperm count, and percentages of motile and morphologically normal spermatozoa) and serum concentration of reproductive hormones (follicle-stimulating hormone, luteinising hormone, testosterone, sex hormone binding globulin, oestradiol, free testosterone and inhibin B).

Results

Sperm concentration, total sperm count and percentage of spermatozoa with normal morphology were negatively associated with increasing habitual alcohol intake. This association was observed in men reporting at least 5 units in a typical week but was most pronounced for men with a typical intake of more than 25 units/week. Men with a typical weekly intake above 40 units had a 33% (95% CI 11% to 59%) reduction in sperm concentration compared to men with an intake of 1–5 units/week. A significant increase in serum free testosterone with increasing alcohol consumption the week preceding the visit was found. Binging was not independently associated with semen quality.

Conclusions

Our study suggests that even modest habitual alcohol consumption of more than 5 units per week had adverse effects on semen quality although most pronounced associations were seen in men who consumed more than 25 units per week. Alcohol consumption was also linked to changes in testosterone and SHBG levels. Young men should be advised to avoid habitual alcohol intake.