bluuebunny/crossref_metadata_2025 huggingface dataset:
Multivessel versus single vessel spasm, as assessed by the intracoronary acetylcholine provocation test, in Korean patients
Authors: Park Ji Young , Rha Seung‐Woon , Jin Zhe , Poddar Kanhaiya L , Ramasamy Sureshkumar , Chen Kang‐Yin , Li Yong‐Jian , Choi Byoung Geol , Ryu Sung Kee , Choi Jae Woong , Song Eun Ju , Ryou Ji Won , Elnagar Amro , Kim Yun Kyung , Na Jin Oh , Choi Cheol Ung , Lim Hong Euy , Kim Jin Won , Kim Eung Ju , Park Chang Gyu , Seo Hong Seog , Oh Dong Joo
Published: September 2011

1. Coronary artery spasm (CAS) is known to be a major cause of myocardial ischaemia. Multivessel coronary spasm (MVS) in particular is likely to induce more severe and prolonged myocardial ischaemia than single vessel spasm (SVS).

2. In the present study, a total of 1082 consecutive patients without significant coronary artery disease who underwent an acetylcholine (ACh) provocation test between March 2004 and April 2009 were investigated. Patients were divided into three groups: an MVS group (n = 275), an SVS group (n = 376) and a non‐CAS group (n = 431). Differences in clinical and angiographic characteristics following the ACh provocation test were evaluated between the MVS, SVS and non‐CAS groups.

3. At baseline, patients in the MVS group had the highest prevalence of peripheral artery disease (PAD), hyperlipidaemia, smoking and old age, as well as the highest triglyceride levels. Calcium channel blockers were most frequently prescribed in MVS patients before the ACh test. During the ACh test, the highest prevalence of chest pain, ischaemic electrocardiogram changes, baseline spasms and diffuse and severe spasms were observed in the MVS group. The response rate to lower ACh doses that induce CAS was also higher in the MVS group. Multivariate analysis showed that the presence of PAD (odds ratio (OR) 2.0; P = 0.006) and baseline spasm (OR 1.4; P = 0.045) were independent predictors of ACh‐induced MVS.

4. In conclusion, ischaemic symptoms, diffuse and severe spasm and baseline spasm were more frequently associated with MVS patients, suggesting more intensive medical therapies and close clinical follow up would be required for this patient group.
Skin manifestations of obesity: a comparative study
Authors: Boza J.C. , Trindade E.N. , Peruzzo J. , Sachett L. , Rech L. , Cestari T.F.
Published: September 2011

Background  Obesity is one of the world’s biggest health problems nowadays. Little research has been done on the skin diseases that affect obese patients.

Objective  To study the prevalence of skin manifestations in obese patients compared with a control group of normal‐weight patients.

Methods  A total of 76 obese patients [body mass index (BMI) ≥30 kg/m2] and 73 with normal‐weight volunteers (BMI 18.5–24.9 kg/m2) were included in the study and had their complete medical history and skin examination evaluated by the same examiner. All patients were investigated for the presence of metabolic syndrome.

Results  The dermatoses that showed a statistically significant relationship with obesity, compared with the control group were: striae (P < 0.001), plantar hyperkeratosis (P < 0.001), acrochordons (P = 0.007), intertrigo (P < 0.001), pseudoacanthosis nigricans (P < 0.001), keratosis pilaris (P = 0.006), lymphedema (P = 0.002) and bacterial infections (P = 0.05). The presence of striae, pseudoacanthosis nigricans and bacterial infections were also found to be correlated with the degree of obesity.

Conclusions  Obesity is strongly related to several skin alterations that could be considered as markers of excessive weight. Skin care of obese patients deserves particular attention, not only because of the high prevalence of cutaneous alteration but mainly because many of these disorders are preventable and could be treated, improving patient’s quality of life.
Porokeratosis: present concepts
Authors: Sertznig P. , von Felbert V. , Megahed M.
Published: September 2011

Porokeratosis represents a group of disorders of epidermal keratinization which are characterized by the histopathological feature of the cornoid lamella, a column of tightly fitted parakeratotic cells. The aetiology of porokeratosis is still unclear. This review summarizes the currently available data on the pathophysiology of this condition and discusses the clinical variants and the currently available therapies.
Carers’ Responses to Challenging Behaviour: A Comparison of Responses to Named and Unnamed Vignettes
Authors: Dagnan Dave
Published: September 2011

Background  The evidence supporting the application of Weiner’s motivational model of helping to the behaviour of carers’ of people with intellectual disabilities and challenging behaviour is inconsistent. One suggested reason for this is that many studies use stimuli that might generate different responses from those to actual instances of behaviour of real people.

Method  Sixty‐two paid carers of people with intellectual disabilities reported attributions, emotions and intended behavioural responses to behaviour presented by an unnamed person and the same behaviour presented by a named and known person. They also completed a scale of behavioural knowledge.

Results  Carers make more internal and global attributions and identify themselves as less optimistic in response to vignettes relating to named and known people than those relating to unnamed people. However, data from both unnamed and named vignettes are consistent in supporting Weiner’s motivational model of helping in demonstrating a mediated model for controllability, anger and helping intention.

Conclusions  Unnamed vignettes may underestimate the intensity of carers’ responses to challenging behaviour; however, this study does not provide evidence that there are qualitative differences in the interrelationships between variables in data sets obtained from unnamed and named vignettes.
C5a/CD88 signaling alters blood–brain barrier integrity in lupus through nuclear factor‐κB
Authors: Jacob Alexander , Hack Bradley , Chen Peili , Quigg Richard J. , Alexander Jessy J.
Published: September 2011

J. Neurochem. (2011) 119, 1041–1051.

Inflammation is a key factor in a number of neurodegenerative diseases including systemic lupus erythematosus. The complement system is an important mechanism in initiating and amplifying inflammation. Our recent studies demonstrate that C5a, a protein fragment generated during complement activation could alter the blood–brain barrier integrity, and thereby disturb the brain microenvironment. To understand the mechanism by which this occurs, we examined the effects of C5a on apoptosis, translocation of nuclear factor‐κB (NF‐κb) and the expression of Iκbα, MAPK, CREB and TJ protein, zona occludens (ZO‐1) in mouse brain endothelial cells. Apoptosis was examined by DNA laddering and caspase 3 activity and the distribution of the ZO‐1 and the p65 subunit of NF‐κB were determined by immunofluorescence. Inhibition of CD88 reduced translocation of NF‐κb into the nucleus, altered ZO‐1 at the interfaces of neighboring cells, decreased caspase 3 activity and prevented apoptosis in these cells. Our results indicate that signaling through CD88 regulates the blood–brain barrier in a NF‐κb‐dependent manner. These studies suggest that the C5a receptor, CD88 is a promising therapeutic target that will reduce NF‐κb‐signaling cascades in inflammatory settings.
Alterations in intrinsic mitochondrial function with aging are fiber type‐specific and do not explain differential atrophy between muscles
Authors: Picard Martin , Ritchie Darmyn , Thomas Melissa M. , Wright Kathryn J. , Hepple Russell T.
Published: September 2011

To determine whether mitochondrial dysfunction is causally related to muscle atrophy with aging, we examined respiratory capacity, H2O2 emission, and function of the mitochondrial permeability transition pore (mPTP) in permeabilized myofibers prepared from four rat muscles that span a range of fiber type and degree of age‐related atrophy. Muscle atrophy with aging was greatest in fast‐twitch gastrocnemius (Gas) muscle (−38%), intermediate in both the fast‐twitch extensor digitorum longus (EDL) and slow‐twitch soleus (Sol) muscles (−21%), and non‐existent in adductor longus (AL) muscle (+47%). In contrast, indices of mitochondrial dysfunction did not correspond to this differential degree of atrophy. Specifically, despite higher protein expression for oxidative phosphorylation (oxphos) system in fast Gas and EDL, state III respiratory capacity per myofiber wet weight was unchanged with aging, whereas the slow Sol showed proportional decreases in oxphos protein, citrate synthase activity, and state III respiration. Free radical leak (H2O2 emission per O2 flux) under state III respiration was higher with aging in the fast Gas, whereas state II free radical leak was higher in the slow AL. Only the fast muscles had impaired mPTP function with aging, with lower mitochondrial calcium retention capacity in EDL and shorter time to mPTP opening in Gas and EDL. Collectively, our results underscore that the age‐related changes in muscle mitochondrial function depend largely upon fiber type and are unrelated to the severity of muscle atrophy, suggesting that intrinsic changes in mitochondrial function are unlikely to be causally involved in aging muscle atrophy.
Metastable Radicals and Intrinsic Chemiluminescence from Soy Proteins
Authors: Liebold Christopher M. , Lei Qingxin , Boatright William L. , Jahan M. Shah
Published: September 2011

Abstract:  Chemiluminescence from various powdered food proteins were examined without the addition of any external source of free radicals or luminescent agents. In the solid‐state, soy and whey proteins produced more intrinsic chemiluminescence than casein, sodium caseinate, or egg albumin. However, when these same food proteins were hydrated, intrinsic chemiluminescence from soy proteins was about 4‐ to 8‐times greater than other source proteins. Quenching the alkyl‐radicals in the powdered soy proteins with hydrogen sulfide reduced the typical electron paramagnetic resonance spectra from soy proteins below detectable levels, and reduced the chemiluminescence from the hydrated soy proteins by about 65%. Antioxidants also reduced chemiluminescence in hydrated soy proteins by about 50% to 92%, with ellagic acid being the most effective. The reduction in chemiluminescence from both quenching radicals in the solid state, and by the addition of antioxidants to aqueous mixtures, indicate that the chemiluminescence produced when soy proteins are hydrated is a free radical catalyzed event. Based on the production of chemiluminescence, the radicals from soy protein were largely released within 30 min of hydration at 23 °C. Elevating the hydration temperatures increased chemiluminescence by as much as 280% at 70 °C, and decreased the half‐life of the light‐emitting reaction by about 9‐fold.

Practical Applications:  Levels of metastable radicals in powdered soy proteins typically range from to 10 to 100 times greater than free radicals from other food protein sources. This research focuses on the types of reactions these radicals catalyze when soy proteins are hydrated, and the radicals suddenly become reactive. The findings suggest that a portion of the energy released from metastable radicals when powdered soy proteins are hydrated is involved in the generation of chemically‐induced light.
Pitfall trapping bias and arthropod body mass
Authors: HANCOCK MARK H. , LEGG COLIN J.
Published: September 2011

Abstract. 1. Pitfall trapping is one of the most widely used arthropod sampling techniques. However, relative species abundance in pitfall trap catches differs from that found using quadrat samples. This difference, here termed bias, reflects the fact that pitfall trap catch is influenced not only by abundance but also by other factors, including activity, which may be linked to body size. Here, we investigate whether the bias affecting pitfall trap catches of a particular species is related to the typical body mass of individuals of that species.

2. Data were extracted from five studies where pitfall trapping bias was quantified and covered 32 species of spiders and carabid beetles. Bias was expressed as the ratio of biomass captured by pitfall traps to that measured by quadrat counts (four field studies), or as the product of mean speed of movement and probability of capture per trap encounter, at standard density (one laboratory study).

3. Pitfall trapping bias and body mass were strongly related on a log–log scale, with log(body mass) explaining 78% of the variation in log(bias) (P < 0.0001). There was no significant effect of arthropod group (spiders, carabids) or study location (field, laboratory).

4. A method is proposed to correct pitfall catches of each of a group of species, based on the typical body mass of an individual of each species. This approach may remove much of the bias in pitfall trap data and so improve the value of this type of data in studies of arthropod communities.
Using meteorological and lunar information to explain catch variability of Orthoptera and Lepidoptera from 250 W Farrow light traps
Authors: STEINBAUER MARTIN J. , HASLEM ANGIE , EDWARDS EDWARD D.
Published: September 2011

Abstract.  1. Farrow light traps have been used in Australia since the 1970s to monitor locusts only, but catch variability has not been explained. Four light traps were operated at North Bourke, northern New South Wales, to study catch variability.

2. Habitat did not influence catch composition (non‐metric multidimensional scaling/analyses of similarity) or similarity. Assemblages of Orthoptera differed only modestly between December and March, whereas assemblages of macrolepidoptera differed strongly between December, March and April.

3. Twenty‐two species of Orthoptera were caught and seven analysed. Kruskal–Wallis ranking tests showed that the largest catches of a species of cricket were obtained when the dominant wind direction was from the SE, whereas the largest catches of three acridid species were obtained when the wind was from the NW. Catch variability of two acridids could be explained by temperature (Generalised linear models); the smallest acridid by wind speed and of the cricket and two acridids by moon surface illumination (K).

4. Eighty‐two species of macrolepidoptera were identified and 17 analysed. The largest catches of a noctuid were obtained when the wind was from the SW; an oenosandrid was only caught when the wind was from the SE or NE. Catch variability of two noctuids, an arctiid and an oenosandrid could be explained by temperature; three noctuids, an arctiid, a cossid and a psychid by relative humidity; a noctuid by wind speed; and two noctuids and two oenosandrids by K.

5. To facilitate comparisons of catches and interpret long‐term population trends, catch variability should be standardised for meteorological/lunar conditions.
Alginate graft copolymers and alginate–co-excipient physical mixture in oral drug delivery
Authors: Wong Tin Wui
Published: September 2011

Objectives

Use of alginate graft copolymers in oral drug delivery reduces dosage form manufacture complexity with reference to mixing or coating processes. It is deemed to give constant or approximately steady weight ratio of alginate to covalently attached co-excipient in copolymers, thereby leading to controllable matrix processing and drug release. This review describes various grafting approaches and their outcome on oral drug release behaviour of alginate graft copolymeric matrices. It examines drug release modulation mechanism of alginate graft copolymers against that of co-excipients in non-grafted formulations.

Key findings

Drug release from alginate matrices can be modulated through using either co-excipients or graft copolymers via changing their swelling, erosion, hydrophobicity/hydrophilicity, porosity and/or drug adsorption capacity. However, it is not known if the drug delivery performance of formulations prepared using alginate graft copolymers is superior to those incorporating graft-equivalent co-excipient physically in a dosage form without grafting but at the corresponding graft weight, owing to limited studies being available.

Conclusions

The value of alginate graft copolymers as the potential alternative to alginate–co-excipient physical mixture in oral drug delivery cannot be entirely defined by past and present research. Such an issue is complicated by the lack of green chemistry graft copolymer synthesis approach, high grafting process cost, complications and hazards, and the formed graft copolymers having unknown toxicity. Future research will need to address these matters to achieve a widespread commercialization and industrial application of alginate graft copolymers in oral drug delivery
Human epithelial carcinoma cytotoxicity and inhibition of DMBA/TPA induced squamous cell carcinoma in Balb/c mice by Acacia catechu heartwood
Authors: Monga Jitender , Chauhan Chetan Singh , Sharma Manu
Published: September 2011

Objectives

Acacia catechu heartwood contains significant amounts of polyphenolic compounds that exhibit powerful antioxidant activity. The purpose of this study was to evaluate the cytotoxicity of A. catechu heartwood extracts in a human epithelial carcinoma cell line (A431) and antitumour activity against DMBA/TPA induced squamous cell carcinoma in Balb/c mice.

Methods

Various extracts, including aqueous, ethyl acetate, chloroform and n-hexane, were tested for cytotoxic properties on a human epithelial carcinoma cell line (A431) by using MTT, sulforhodamine B and lactate dehydrogenase leakage assays. The standardized A. catechu heartwood aqueous extract (AQCE) was further evaluated for antitumour activity against 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA) induced skin carcinoma in Balb/c mice.

Key findings

The results showed that administration of AQCE showed a dose-dependent growth inhibition response, with an IC50 value of 78.56 µg/ml. Tumour incidence was significantly decreased (P < 0.001) to 30% with AQCE compared with 100% in the DMBA/TPA group. The AQCE was also found to significantly upregulate different antioxidant enzymes in skin and liver tissue.

Conclusions

The results suggest that AQCE may exert its chemopreventive activity by acting as an antioxidant.
Anaesthetics differentially modulate the trigeminocardiac reflex excitatory synaptic pathway in the brainstem
Authors: Wang Xin , Gorini Christopher , Sharp Douglas , Bateman Ryan , Mendelowitz David
Published: September 2011

Non‐Technical Summary  Activation of the trigeminal nerve during eye and head surgery often evokes a dramatic decrease in heart rate, blood pressure and breathing rate, referred to as the trigeminocardiac reflex. Different anaesthetics can depress or amplify this reflex with serious clinical consequences. In this study we focused on two populations of neurones, the neurones that receive sensory information and the neurones that control heart rate. We show that these two groups of neurones in the brain are activated in the reflex circuitry and how different anaesthetics differentially modulate the neurotransmission to these neurones. These results help us understand the mechanisms and anaesthetic modulation of the trigeminocardiac reflex and can help reduce its rate of occurrence and increase patients’ safety during surgery.
Aircraft Cabin Tonal Noise Alleviation Through Fuselage Skin Embedded Piezoelectric Actuators
Authors: Testa C. , Bernardini G. , Gennaretti M.
Published: September 2011

An integrated spectral-integral formulation is applied for prediction and active control of the noise generated by propellers inside the cabin of a general aviation aircraft. It consists of a multidisciplinary approach that involves interaction among exterior noise field, elastic fuselage dynamics, interior acoustics, and control system. A fuselage skin embedding piezoelectric elements is supposed to be impinged by external sound waves generated by propellers. An optimal harmonic control approach is applied for the actuation of the piezoelectric patches, aimed at alleviating the corresponding cabin noise. The aeroacoustoelastic plant model considered in the control problem is obtained by combining modal approaches for the description of cabin acoustic field and fuselage shell dynamics, with a boundary element method scattering formulation for the prediction of exterior pressure disturbances. Considering the fuselage of a general aviation aircraft impinged by noise generated by a couple of pulsating point sources moving with it, numerical results examine the effectiveness of the control approach applied to several configurations of piezoelectric actuators.
Exact Solutions for a Thermal Nonequilibrium Model of Fluid Saturated Porous Media Based on an Effective Porosity
Authors: Kuwahara F. , Yang C. , Ando K. , Nakayama A.
Published: September 2011

An effective porosity concept has been introduced to account for the effects of tortuosity and thermal dispersion on the individual effective thermal conductivities of the solid and fluid phases in a fluid-saturated porous medium. Using this effective porosity concept, a thermal nonequilibrium model has been proposed to attack locally thermal nonequilibrium problems associated with convection within a fluid-saturated porous medium. Exact solutions are obtained, assuming a plug flow, for the two cases of thermally fully developed convective flows through a channel, namely, the case of isothermal hot and cold walls and the case of constant heat flux walls. These exact solutions for the cases of metal foam and air combination reveal that the local thermal equilibrium assumption may hold for the case of isothermal hot and cold walls, but may fail for the case of constant heat flux walls.
Experimental Study on Single-Phase Gas Flow in Microtubes
Authors: Zhang T. T. , Jia L. , Li C. W. , Yang L. X. , Jaluria Y.
Published: September 2011

An experimental system for single-phase gas flow in microtubes has been developed. The effects of viscous heating and compressibility on the flow and temperature field were studied for a wide range of governing parameters. Also, an analytical/numerical model of the flow was developed. Numerical results for the flow and heat transfer in the slip flow region were found to agree quite well with the experimental data, lending support to the model. The study provides greater physical insight into and understanding the effects of viscous dissipation and compressibility in microtube flow and the associated heat transfer. In addition, the combined experimental and numerical simulation approaches of the process can be used for control and optimization of systems based on microtube heat transfer.
Three-Dimensional Endmill Dynamics: Modal Development and Experimental Validation
Authors: Bediz Bekir , Kumar Uttara , Ozdoganlar Burak , Schmitz Tony L.
Published: September 2011

In this paper the three-dimensional dynamic behavior of macro-scale milling tools is modeled using the spectral-Tchebychev technique while considering the actual fluted cross-sectional geometry and pretwisted shape of the tools. The bending and torsional behavior of three different fluted endmills is compared to finite element predictions and experimental results obtained using impact testing with free-free boundary conditions. The percent difference between experiment and the spectral-Tchebychev method predictions is shown to be 3% or less for all three tools while considering the first six bending modes and first two torsional modes. For the same modes, the spectral-Tchebychev and finite element model predictions agreed to better than 1%.
Design and Fabrication of an Automatic Nanoscale Tool-Tip Exchanger for Scanning Probe Microscopy
Authors: Sahu Bijoyraj , Taylor Curtis R. , Riddle Robert O. , Leang Kam K.
Published: September 2011

The scanning probe microscope (SPM), in particular the atomic force microscope (AFM), is widely used as a metrology tool at the nanoscale. Recently, the instrument has shown tremendous potential to perform various nanoscale fabrication processes (e.g. nanolithography, atomic deposition, nanomachining, etc.) with high resolution (< 10 nm). However, use of SPMs for fabrication have a low throughput and require frequent manual replacement of the SPM tips due to damage or wear. Manual switching of tips for multiple operations, is relatively time consuming. Thus these issues hinder the throughput, quality, reliability, and scalability of SPM as a practical tool for nanofabrication. To address these issues, this paper presents the design, analysis, and fabrication of a novel nano tool-tip exchanger that automatically loads and unloads SPM tool-tips. The ability to provide fully automated on-demand tool-tip exchange would enable SPM as a scalable tool for nanomanufacturing. In this work, an active SPM cantilever is designed with an electrothermally actuated microgripper capable of locating, loading, and unloading tool-tips automatically. The microgripper has been designed to provide adequate range of actuation, gripping force, stiffness, and dynamic response required for securely holding the tool-tip and for functioning within existing SPM-based systems. The design has been validated by finite element analysis. Experiments have been conducted to establish the micro-electro-mechanical systems (MEMS) fabrication processes for successful fabrication of the prototype.
An Investigation on Top Surface Quality for Direct Metal Laser Fabrication
Authors: Yang Jialin , Xu Chao , Wang Yang
Published: September 2011

SLS (Selective Laser Sintering) has been developing rapidly since its initial invention for non-metal materials by Texas University. Nowadays, Direct Metal Laser Fabrication (DMLF), as a variant of SLS technique, has been investigated intensively which is aimed at rapid manufacturing of end-use metal products with full functions. For describing the stability and properties of DMLF process, Top Surface Quality (TSQ) was put forward in this paper, which could be a unique and crucially important feature compared with traditional manufacturing methods. Through the systematic and detailed analysis of DMLF process using related theories of additive manufacturing technologies, it was revealed that TSQ was the key factor for controlling the stability of DMLF process and thus tailoring final properties of metallic parts. TSQ was defined as the surface morphology in macro and micro scopes in laser scanning area of unit layers during DMLF, and could be characterized by three key elements: flatness, compactness and cleanliness. Only good TSQ could ensure the stability of DMLF process and excellent performance of metal parts in theory. The flatness was the significant factor to assure the shaping during DMLF while the compactness and cleanliness are the decisive factors to assure the final properties of metal part for DMLF. As an example, the typical top surface defects and their contributing factors in DMLF for Cu-based metal powder mixtures were investigated thoroughly according to the proposed definition and requirements. Moreover, the specific controlling methods of TSQ were provided and discussed. Eventually, DMLF of three-dimensional Cu-based metal sample with complicate structure was successfully performed by taking some effective measures for adjusting TSQ parameters.
Development of a Multi-Axis WEDM Process
Authors: Bohlmann Birgit , Buresch Josef , Haas Ru¨diger
Published: September 2011

A multi-axis WEDM technology is currently developed with an industrial consortium. To achieve this advanced application technology a CAM software and a machine prototype with an integrated two-axis round table was developed and first tests conducted. The assembly of the additional swing and rotational axis and the simultaneous steering with the machine axes enables the manufacturing of complex parts. But only in combination with the CAM software transforming complex shapes into NC programs for 6- and 7-axis manufacturing, the machining of complex geometries is feasible. At present, the technology is adapted to the manufacturing of medical parts from titanium alloys and CoCr alloys. First results of the machining of an involute gear will be presented.
Methodology for Solving the Assembly System Reconfiguration Planning Problem
Authors: Bryan A. , Hu S. J. , Koren Y.
Published: September 2011

The need to cost effectively introduce new generations of product families within ever decreasing time frames have led manufacturers to seek product development strategies with a multigenerational outlook. Co-evolution of product families and assembly systems is a methodology that leads to the simultaneous design of several generations of product families and reconfigurable assembly systems that optimize life cycle costs. Two strategies that are necessary for the implementation of the co-evolution of product families and assembly systems methodology are: (1) The concurrent design of product families and assembly systems and (2) Assembly system reconfiguration planning (ASRP). ASRP is used for the determination of the assembly system reconfiguration plans that minimize the cost of producing several generations of product families. More specifically, the objective of ASRP is to minimize the net present cost of producing successive generations of products. This paper introduces a method for finding optimum solutions to the ASRP problem. The solution methodology involves the generation of a staged network of assembly system plans for all the generations that the product family is expected to be produced. Each stage in the network represents a generation that the product family is produced, while each state within a stage represents a potential assembly system configuration. A novel algorithm for generating the states (i.e. assembly system configurations) within each generation is also introduced. A dynamic program is used to find the cost minimizing path through the network. An example is used to demonstrate the implementation of the ASRP methodology.
Energy Management in Manufacturing Systems
Authors: Chang Qing , Xiao Guoxian , Li Lin , Biller Stephan
Published: September 2011

Conventionally, improving production efficiency, flexibility and responsiveness has been the primary research focus of production management, while energy consumption has received relatively little attention. Energy consumption plays a more and more important role in manufacturing environment. This is mainly driven by energy cost and environmental concerns. When the energy system becomes complicated and coupled with ongoing production, it is very difficult to hunt the “hidden treasure” which affects the overall benefit of a manufacturing system. This paper provides a systematic method for energy management in a production system. We start from dynamic production transient analysis and provide quantitative analysis for energy saving opportunity in a system. Furthermore, energy saving is integrated into production system which includes downtime and throughput to provide integrated energy management framework for a production system. A case study is conducted to demonstrate its potential on energy savings in a multi-stage manufacturing system.
Comparative Analysis of the Process Mechanics in Micro-Electrical Discharge Machining (EDM) and Reverse Micro-EDM
Authors: Mastud Sachin , Singh Ramesh K. , Samuel Johnson , Joshi Suhas S.
Published: September 2011

The objective of this paper is to study the time-evolution of the process mechanics for micro-electrical discharge machining (MEDM) and reverse-micro-electrical discharge machining (R-MEDM), as a function of key system parameters, viz., voltage, capacitance, and threshold of the spark circuit. Full factorial experiments have been performed to quantify the aforementioned system parameters on the MEDM and R-MEDM processes. The process monitoring voltage and current signals, material erosion rate and the surface roughness values are the machining responses of interest. The voltage and current (V-I) signals reveal information about the material erosion rate and the extent of debris-interference associated with the corresponding process. Analysis of the V-I signals shows that R-MEDM is more stable than MEDM and can therefore be operated at aggressive conditions of capacitance and voltage. R-MEDM also results in higher material erosion rates but the resulting surface has a higher surface roughness value than that generated by MEDM. A debris deposition mechanism is proposed for R-MEDM that suggests debris entrapment and subsequent welding to the machined feature to be the reason for the increased surface roughness.
Micro Feature Enhanced Sinter Bonding of Metal Injection Molded (MIM) Parts to Solid Substrate
Authors: Martens Thomas , Mears Laine
Published: September 2011

In MIM, fine metal powders are mixed with a binder and injected into molds, similar to plastic injection molding. After molding, the binder is removed from the part, and the compact is sintered to almost full density. The obstacle to sinter bonding a MIM part to a conventional (solid) substrate lies in the sinter shrinkage of the MIM part, which can be up to 20%, meaning that the MIM part shrinks during sintering, while the conventional substrate maintains its dimensions. This behavior would typically inhibit bonding and/or cause cracking and deformation of the MIM part. A structure of micro features molded onto the surface of the MIM part allows for shrinkage while bonding to the substrate. The micro features tolerate certain plastic deformation to permit the shrinkage without causing cracks after the initial bonds are established. In a first series of tests, bond strengths of up to 80% of that of resistance welds have been achieved. This paper describes how the authors developed their proposed method of sinter bonding and how they accomplished effective sinter bonds between MIM parts and solid substrates.
Finite Element Predictions for a Cold Sheet Metal Forming Process Using Tetrahedral Mini-Elements
Authors: Lee Min-Cheol , Sim Sang-Hyun , Eom Jae-Gun , Joun Man-Soo , Chung Wan-Jin
Published: September 2011

In this paper, finite element prediction of a cold sheet metal forming process is investigated using solid elements. A three-dimensional rigid-plastic finite element method with conventional linear tetrahedral MINI-elements [1, 2] is employed. This technique has traditionally been used for bulk metal forming simulations. Both single- and double-layer finite element mesh systems are studied, with particular attention to their effect on the deformed shape of the workpiece and thickness variation. The procedure is applied to the well-known problem of the NUMISHEET93 international benchmark. The resulting predictions are compared with experimental observations found in the literature, and good agreement is noted.
Analysis of a Simultaneous CNC Turning and Boring Operation via Multisensor Monitoring
Authors: Deane Erick , Hernandez Manuel , Giesecke David , Meanor Matthew , Collins Schadrick , Ji Yingfeng , Xu Chengying
Published: September 2011

The introduction of multi-axis CNC machining has reduced machining time and increased production rates. However, optimizing simultaneous operations to produce quality parts and prolong tool life still possesses a challenge to engineers due to the mutual interactions of two tools removing material and the amount of factors and noise in a production environment. Since there are multiple factors and the sources of error are unknown, we use a statistical approach to obtain and organize information. A design of experiment study was implemented across twelve sensor responses to optimize the spindle speed, feed rate, inner diameter (ID) depth of cut and outer diameter (OD) depth of cut for simultaneous turning and boring roughing operations. The optimal machining conditions were obtained by a response optimizer from Minitab 16 statistical software. The optimized settings result in 13% reduced cutting and 10% reduced total power consumption for a 3% increase of average power. Future studies will cross correlate different responses to reduce the number of sensors in developing a robust adaptive controller for chatter detection and tool condition monitoring.
Investigating the Effect of Miniaturization on the Microtensile Properties of Brass (CuZn30)
Authors: Wuertemberger Lauren B. , Chann Megan N. , Onyancha Richard M.
Published: September 2011

As everyday equipment becomes smaller and smaller, it is of increasing importance that the manufacturing processes used for metals are capable of producing parts of appropriate sizes. Currently, manufacturing processes assume macromaterial properties can be applied for microscale production, but is this a valid assumption? This paper investigates the accuracy of applying macroscale tensile properties in microscale applications. In order to test the soundness of this supposition, tensile tests were performed on both macroscale and microscale brass specimens, and the resulting calculated material properties, strain hardening exponent (n) and strength coefficient (K), were compared. Specimens were heat treated to various temperatures before tensile tests were performed, and the strength coefficient and strain hardening exponents of micro and macro tensile specimens were compared. Additionally, it is investigated whether average grain size correlates to material properties. The results showed that in general it is not accurate to apply macroscale tensile properties to microscale applications. However, at mesocale grain sizes, (12–20 microns), the strain hardening exponent values were similar for both macro and microscale specimens.
An Analysis of the Wear of Tungsten Carbide and Polycrystalline Diamond Inserts Turning Ti-6Al-4V
Authors: Schrock David , Wang Xin , Kwon Patrick
Published: September 2011

Dry turning experiments on Ti-6Al-4V were conducted using two grades (finer and coarser) of carbides and polycrystalline diamond (PCD) inserts to study tool wear. Despite of minor compositional difference between two carbide grades, both grades contain 6% Co. Crater wear and flank wear were measured using Confocal Laser Scanning Microscopy (CLSM). Three dimensional rake surface topographies were reconstructed from the CLSM data and wear profiles were extracted. Finite Element Analysis (FEA) was conducted to study the effects of cutting conditions and thermal properties on rake face temperature. Flank wear on the carbide tools indicated that the inserts with the finer grain size exhibited smaller flank wear than the insert of the coarser grain size. This was attributed to reduced abrasive wear in the finer grained inserts as a result of a higher hardness. The carbide grade with a coarser grain size had an enhanced ability to resist crater wear, likely from lower rake face temperatures and the differences in the compositions. It is known that coarser grain carbides have a higher thermal conductivity resulting from increased grain contiguity. FEA was used to study the temperature difference between the two grain-sizes and the effect of thermal conductivity on temperature gradients. Tool wear of the PCD inserts was also studied. The PCD tools showed significant adhesive wear at the 200sfm cutting speed, transitioning to crater wear at 400sfm. With a high thermal conductivity, it is possible that rake face temperatures were low enough to alter the wear mechanism. FEA supports this hypothesis, as the maximum rake face temperature for the PCD inserts were only around 900°C at 200sfm.
Sheet Orientation Effects on the Formability Limits of the AZ31B Magnesium Alloy at SPF Conditions
Authors: Abu-Farha Fadi , Deeter Brad
Published: September 2011

The formability curves of the AZ31B magnesium alloy were constructed by following a novel approach that best resembles the conditions of actual Superplastic Forming (SPF) operations. Sheet samples were formed at 400 °C and a constant strain rate of 1×10−3 s−1, by free pneumatic bulging into a set of progressive elliptical die inserts. By doing so, the material in each of the formed domes was forced to undergo biaxial stretching at a distinct strain ratio, which is simply controlled by the geometry (aspect ratio) of the selected die insert. Material deformation was quantified using circle grid analysis (CGA), and the recorded planar strains were used to construct the forming limit diagram (FLD) of the material. The aforementioned was carried out with the sheet oriented either along or across the direction of major strains, in order to establish the relationship between the material’s rolling direction and the corresponding limiting strains. Great deviations between the two sets of formability curves are realised, hence a compound forming limit diagram is constructed as an improved way for characterising the material behaviour. The presented pneumatic stretching approach is shown to produce accurate friction-independent formability diagrams, with clear distinction between the safe and unsafe deformation zones, even though the developed diagrams are confined to the biaxial strain region (right side quadrant of an FLD). Moreover, the approach proves to be a viable means for providing formability maps under conditions where traditional mechanical stretching techniques (Nakajima and Marciniak tests) are limited.
A Quantitative Study of Illumination Techniques for Machine Vision Based Inspection
Authors: Yan Michael T. , Surgenor Brian W.
Published: September 2011

In this paper, three basic lighting geometries are compared quantitatively in an inspection task that checks for the presence of J-clips on an aluminum carrier. Two independent LabVIEW® machine vision algorithms were used to evaluate backlight, bright field and dark field illumination on their ability to minimize variations within a pass (clip present) or fail (clip absent) sample set, as well as maximize the separation between sample sets. Results showed that there were clear differences in performance with the different lighting geometries, with over a 30% change in performance. Although it is widely acknowledged that the choice of lighting is not a trivial exercise for machine vision systems, this paper provides a case study of the quantitative performance of different lighting geometries.
Theoretical Modeling of Cutting Temperature Distribution by Considering the Material Thermal Properties as Functions of Temperature
Authors: Kang Zheng , Ji Xia , Zhang Xueping , Liang Steven Y.
Published: September 2011

To better predict the temperature distribution in the tool and chip, a modified theoretical model by considering material thermal properties as temperature dependent is developed to quantitatively describe the temperature elevation due to the shear and friction at the tool-chip interface. Work’s thermal properties of thermal conductivity and specific heat are modified and considered as functions of temperature. The semi-infinite method is utilized in the model, in which the back of the chip and the shear band are assumed as adiabatic. Temperature distribution in the tool and chip is then determined simultaneously by shear and friction. An imaginary heat source is set up to be plane-symmetric with respect to each original heat source in this approach. The effects of original heat source and imaginary heat source are superimposed to calculate the final temperature elevation in the tool and chip. To determine the ratio of total heat transferred into the chip and the tool, it is assumed that the temperatures in the tool and in the chip are in balance along the tool-chip interface in the stable cutting state. The model is experimentally validated with peak temperature data from previous literature. Results indicate that the model-experiment deviation is less than 10% when thermal properties are considered temperature dependent, and it is more accurate than that by considering the thermal properties as constants. The patterns of temperature distribution in the tool and chip are further analyzed by the model.
Effect on Flow Stress of a Rapid Phase Transition in AISI 1045 Steel
Authors: Burns Timothy J. , Mates Steven P. , Rhorer Richard L. , Whitenton Eric P. , Basak Debasis
Published: September 2011

New experimental data on AISI 1045 steel from the NIST pulse-heated Kolsky Bar Laboratory are presented. The material is shown to exhibit a nonequilibrium phase transformation at high strain rate. An interesting feature of these data is that the material has a stiffer response to compressive loading when it has been preheated to a testing temperature that is below the eutectoid temperature using pulse-heating than it does when it has been preheated using a slower heating method. On the other hand, when the material has been pulse-heated to a temperature that exceeds the eutectoid temperature prior to compressive loading on the Kolsky bar, it is shown to exhibit a significant loss of strength. A consequence of this behavior is that fixed-parameter constitutive models, such as the well-known Johnson-Cook model, cannot be used to describe this constitutive response behavior. An argument is made that the phase transition does not occur during high-speed machining operations, and suggestions are made as to how to modify the Johnson-Cook model of Jaspers and Dauzenberg for this material in order to obtain improved temperature predictions in finite-element simulations of high-speed machining processes.
Characterization of Tensile and Compressive Behavior of Microscale Sheet Metals Using a Transparent Micro-Wedge Device
Authors: Magargee James , Cao Jian , Zhou Rui , McHugh Morgan , Brink Damon , Morestin Fabrice
Published: September 2011

The cyclic and compressive mechanical behavior of ultra-thin sheet metals was experimentally investigated. A novel transparent wedge device was designed and fabricated to prevent the buckling of thin sheets under compressive loads, while also allowing full field strain measurements of the specimen using digital imaging methods. Thin brass and stainless steel sheet metal specimens were tested using the micro-wedge device. Experimental results show that the device can be used to delay the onset of early buckling modes of a thin sheet under compression, which is critical in examining the compressive and cyclic mechanical behavior of sheet metals.
On the Volumetric Assessment of Tool Wear in Machining Inserts With Complex Geometries: Need, Methodology and Validation
Authors: Kuttolamadom Mathew A. , Mears M. Laine
Published: September 2011

The objective of this paper is to qualitatively assess the inadequacies of the current manner of tool wear quantification and consequently to suggest/develop a more comprehensive approach to machining tool wear characterization. Traditional parameters used for tool wear representation such as flank and crater wear are no longer self-sufficient to satisfactorily represent the wear of the complex geometric profiles of more recent cutting tools. These complexities in tool geometries are all the more pronounced when catering to difficult-to-machine materials such as titanium and its alloys. Hence, alternatives to traditional tool wear assessment parameters are briefly explored and a suitable one is selected, that will help understand the very nature of the evolving wear profile itself from a three dimensional standpoint. The assessment methodology is further developed and standardized and suggestions for future use and development provided. The measurement system is evaluated using a gauge repeatability and reproducibility (R&R) study as well. The method is deployed for assessing tool wear during the machining of Ti-6Al-4V at selected process conditions for validation purposes. Further, concepts such as the M-ratio and its derivatives are developed to quantify the efficiency of the cutting tool during each pass as a function of time at a theoretically constant material removal rate (MRR).
Controlled Nanocrystallization of NiTi Shape Memory Alloy by Laser Shock Peening
Authors: Ye Chang , Cheng Gary J.
Published: September 2011

In this paper, partial amorphization of NiTi alloys by laser shock peening (LSP) is reported. The microstructure of NiTi after LSP was characterized by transmission electron microscopy (TEM). The amorphization mechanism was discussed in light of the high strain rate deformation characteristics of LSP. With subsequent controlled annealing after LSP, nanostructure with different grain size distribution was achieved.