Plastic forming simulations of cold isostatic pressing of selective laser sintered components

A combined method of selective laser sintering （SLS） and cold isostatic pressing （CIP） was applied to manufacturing metal parts rapidly. Finite element method was used to predict final dimensions and decrease cost. The simulations of CIP of selective laser sintered parts were carried out by Drucker-Prager-Cap constitutive model with ABAQUS computer program. The property of metal powder was measured by CIP experiments. The results show the rubber bag and the friction coefficient have little influence on results of simulations. The parts only have uniform shrinkage and have no obvious distortion in shape. The results of simulations show a good agreement with the experimental results and the calculated results, indicating that the Drucker-Prager-Cap model is an effective model to simulate CIP process. The simulations could give a useful direction to forming process of the CIP of selective laser sintered components. K

Viscous warm pressure bulging process of AZ31B magnesium alloy with different ellipticity dies

Based on the bulging principle of different ellipticity dies, the methyl vinyl silicone rubber with excellent thermal stability and heat transfer performance was chosen as the viscous medium. The finite element analysis and experiments of viscous warm pressure bulging （VWPB） of AZ31B magnesium alloy were conducted to analyze the influence of different ellipticity dies on the formability of AZ31B magnesium alloy. At the same time, based on the grid strain rule, the forming limit diagram （FLD） of VWPB of AZ31B magnesium alloy was obtained through measuring the strain of bulging specimens. The results showed that at the temperature range of viscous medium thermal stability, the viscous medium can fit the geometry variation of sheet and generate non-uniform pressure field, and as the die ellipticity increases, the difference value of non-uniform pressure reduces. Meanwhile, according to the FLD, the relationship between part complexity and ultimate deformation was investigated.

Resistivity Instability in Polysilicon Resistors Under Metal Interco-nnects and Its Suppression by Compensating Ion Implantation

The resistivity instability of the boron-doped polysilicon resistors being a line resistance element of ICs is within the range of several kΩ's,especially when our running the underneath metal interconnects.Polysilicon resistors have been fabricated under various processing conditions as well as some electrical and crystallographic characteristics have been obtained.It is shown the resistivity instability mainly results from the variational carrier mobility.By analyzing the Seto's model,the barrier height and trapped charge density are observed reducing under the Al over layer.Therefore,the resistance instability is also caused by both the charge trapping/detrapping occurring at polysilicon grain boundaries and the resultant variation in the potential barrier height.The formation of high-stability polysilicon resistors in the range of several kΩ's has been decided by compensating the ion implantation,which makes the charge trapping/detrapping at the grain boundary less susceptible to the hydrogen annealing.

Synthesis and Surface Activity of Heterogemini Imidazolium Surfactants

A series of heterogemini imidazolium surfactants with two-methylene spacer groups （[Cm- 2-Cnim]Br2, m, n=8, 10, 12, 14, 16; m≠n） have been synthesized and characterized by 1H NMR and ESI-MS spectroscopy. The effects of various reaction parameters, including stoichiometry, reaction temperature and time, were investigated. In addition, the surface activity study about heterogemini imidazolium surfactants was carried out and the influences of dissymmetric degree on the surface properties were also discussed.

Analysis of Volatile Constituents in Bamboo Leaves Using HS-GC/MS

[Objective] This study aimed to analyze the volatile constituents in bamboo leaves. [Method] The volatile compositions in bamboo leaves were analyzed by headspace-gas chromatography-mass spectrometry （HS-GC/MS）, and identified by searching their mass spectra in NIST database. The relative percentages of them were calculated by the GC peak areas. [Result] Fifty-three chemical constituents in bamboo leaves were separated. Among them, the main components were alcohols, ketones and aldehydes, and these compounds contained unsaturated bonds. [Con- clusion] HS-GC/MS was simple and less sample-demanding and can be used for rapid analysis of volatile constituents in bamboo leaves and provide scientific basis for further research and development of bamboo leaves.

Synthesis, Characterization and Antibacterial Activity of New Ln(Ⅲ) Complexes with an Unsymmetrical Schiff Base Ligand

A new unsymmetrical Schiff base ligand (H2LLi) was synthesized using L-lysine, salicylaldehyde and 2-hydroxy-1-naphthaldehyde. Three solid metal complexes of this ligand \[Ln(H2L)(NO3)\] NO3·2H2O (Ln=La, Sm, Ho) have been prepared and characterized by elemental analyses, IR spectra, UV spectra, TG-DTG and molar conductance. The antibacterial activities of the ligand and its complexes are also studied. The antibacterial experiments indicate that the ligand and its complexes possess antibacterial activity against Escherichia coli, Staphylococcus aureus and Bacillus subtilis and that the complexes have higher activity than those of the ligand.

Performance on the Functional Movement Screen in older active adults

Background:The Functional Movement Screen(FMS^(TM)) has become increasingly popular for identifying functional limitations in basic functional movements.This exploratory and descriptive study was undertaken to confirm feasibility of performing the FMS^(TM) in older active adults,assess prevalence of asymmetries and to evaluate the relationship between functional movement ability,age,physical activity levels and body mass index(BMI).Methods:This is an observational study;97 men(n = 53) and women(n = 44) between the ages of 52 and 83 participated.BMI was computed and self-reported physical activity levels were obtained.Subjects were grouped by age(5-year intervals),BMI(normal,over-weight,and obese)and sex.Each participant's performance on the FMS^(TM) was digitally recorded for later analysis.Results:The youngest age group(50–54 years) scored highest in all seven tests and the oldest age group(75+) scored lowest in most of the tests compared to all other age groups.The subjects in the 'normal weight' group performed no different than those who were in the 'overweight' group;both groups performed better than the 'obese' group.Of the 97 participants 54 had at least one asymmetry.The pairwise correlations between the total FMS^(TM) score and age(r =-0.531),BMI(r =-0.270),and the measure of activity level(r = 0.287) were significant(p < 0.01 for all).Conclusion:FMS^(TM) scores decline with increased BMI,increased age,and decreased activity level.The screen identifies range of motion-and strength-related asymmetries.The FMS^(TM) can be used to assess functional limitations and asymmetries.Future research should evaluate if a higher total FMS^(TM) score is related to fewer falls or injuries in the older population.

Characteristics of common solid liver lesions and recommendations for diagnostic workup

Due to the widespread clinical use of imaging modalities such as ultrasonography,computed tomography and magnetic resonance imaging (MRI),previously unsuspected liver masses are increasingly being found in asymptomatic patients.This review discusses the various characteristics of the most common solid liver lesions and recommends a practical approach for diagnostic workup.Likely diagnoses include hepatocellular carcinoma (the most likely;a solid liver lesion in a cirrhotic liver) and hemangioma (generally presenting as a mass in a non-cirrhotic liver).Focal nodular hyperplasia and hepatic adenoma should be ruled out in young women.In 70% of cases,MRI with gadolinium differentiates between these lesions.Fine needle core biopsy or aspiration,or both,might be required in doubtful cases.If uncertainty persists as to the nature of the lesion,surgical resection is recommended.If the patient is known to have a primary malignancy and the lesion was found at tumor staging or follow up,histology is required only when the nature of the liver lesion is doubtful.

Improved direct power injection model of 16-bit microcontroller for electromagnetic immunity prediction

To promote the modeling standardization process of the integrated circuits, an improved electrical simulation model for a direct power injection （DPI） setup which was used to measure the conducted immunity of a 16-bit microcontroller to radio frequency aggression was investigated. Based on the existing model of the same microcontroller, the PDN module was modified by adding the core, PLL and MD network models, which could reflect the actual electric distribution situation within the microcontroller more accurately. By comparing the simulation results with the measurement results, the effectiveness of the modified model can be improved to 500 MHz, and its uncertainty is within ＋1.8 dB （＋2 dB is acceptable）. Then, to improve the simulation accuracy of the complete model in the high frequency range, the I/O model which contained the dynamic and nonlinear characteristics reflecting the variation of the internal impedance of the microcontroller with increasing the frequency of the external noise was introduced. By comparing the simulation results with the measurement results, the effectiveness of the second modified model can be improved up to 1.4 GHz with the uncertainty of ~1.8 dB. Thus, a conclusion can be reached that the proposed model can be applied to a much wider frequency range with a smaller uncertainty than the latest model of the similar type. Furthermore, associated with the electromagnetic emission testing platform model, the PDN module can also be used to predict the electromagnetic conducted and radiated emission characteristics. This modeling method can also be applied to other integrated circuits, which is very helpful to the standardization of the IC electromagnetic compatibility （EMC） modeling process.

Mining truck scheduling with stochastic maintenance cost

Open pit mining operations utilize large scale and expensive equipment. For the mines implementing shovel and truck operation system, trucks constitute a large portion of these equipment and are used for hauling the mined materials. In order to have sustainable and viable operation, these equipment need to be utilized efficiently with minimum operating cost. Maintenance cost is a significant proportion of the overall operating costs. The maintenance cost of a truck changes non-linearly depending on the type, age and truck types. A new approach based on stochastic integer programming （SIP） techniques is used for annually scheduling a fixed fleet of mining trucks in a given operation, over the life of mine （multi-year time horizon） to minimize maintenance cost. The maintenance cost data in mining usually has uncertainty caused from the variability of the operational conditions at mines. To estimate the cost, usually historic data from different operations for new mines, and/or the historic data at the operating mines are used. However, maintenance cost varies depending on road conditions, age of equipment and many other local conditions at an operation. Traditional models aim to estimate the maintenance cost as a deterministic single value and financial evaluations are based on the estimated value. However, it does not provide a confidence on the estimate. The proposed model in this study assumes the truck maintenance cost is a stochastic parameter due to the significant level of uncertainty in the data and schedules the available fleet to meet the annual production targets. The scheduling has been performed by applying both the proposed stochastic and deterministic approaches. The approach provides a distribution for the maintenance cost of the optimized equipment schedule minimizing the cost.

Effect of key factors on cold orbital forging of a spur bevel gear

Cold orbital forging is an advanced spur bevel gear forming technology. Generally, the spur bevel gear in the cold orbital forging process is formed by two steps: the preforming step and the final step. Due to the great importance of the final step to gear forming and its complication with interactive factors, this work aims at examining the influence of key factors on the final step in cold orbital forging of a spur bevel gear. Using the finite element(FE) method and control variate method, the influence rules of four key factors, rotation velocity of the upper tool, n, feeding velocity of the lower tool, v, tilted angle of the upper tool, γ, friction factor between the tools and the billet, m, on the geometry and the deformation inhomogeneity of the cold orbital forged gear are thoroughly clarified. The research results show that the flash becomes more homogeneous with increasing v, increasing m, decreasing n or decreasing γ. And the deformation of the gear becomes more homogeneous with increasing v, decreasing n or decreasing γ. Finally, a corresponding experiment is conducted, which verifies the accuracy of FE simulation conclusions.

Adult autoimmune enteropathy

Recent reports have suggested that autoimmune enteropathy involving the small bowel may occur in adults as well as in children. Apparently, the endoscopic and histological changes are similar to celiac disease before treatment, but these are not altered by any form of dietary restriction, including a gluten-free diet. As in celiac disease, histologic changes in gastric and colonic biopsies have also been recorded. Anti-enterocyte antibodies detected with immunofluorescent methods have been reported by a few laboratories, but these antibodies appear not to be specific and may simply represent epiphenomena. A widely available, reproducible and quantitative anti-enterocyte antibody assay is needed that could be applied in small bowel disorders that have the histological appearance of celiac disease, but fail to respond to a gluten-free diet.

Climate Change Risk Research: A Case Study on Flood Disaster Risk in China

This paper discusses theories and methods of climate change risk studies for the research expansion in China. Climate change risks consist of three basic components including sensitivity, exposure, and possibility. Uncertainty, future events, damages, and relativity are the major features of climate change risk. Climate change risk research includes two key steps: risk assessment and risk management, the former is the process, and the latter is the ultimate goal which is the basis for actions to address climate change. We present the main framework and methods for climate change risk research. A case study on China's floods risk is taken as an example of climate change risk study. Finally, we point out main aspects of climate change risk research, including ensemble-based probabilistic projection, quantitative risk assessment, risk zoning and mapping, and risk management.

Factors that impact health-related quality of life in adults with celiac disease:A multicenter study

AIM: To evaluate the factors involved in the impairment of health-related quality of life (HRQOL) in patients with celiac disease.METHODS: A multicenter, cross-sectional prospective study was performed in patients with celiac disease who completed two HRQOL questionnaires: the gastrointestinal quality of life index (GIQLI) and the EuroQol-5D (EQ).RESULTS: Three hundred and forty patients (163 controlled with a gluten-free diet, and 177 newly diagnosed with a normal diet) were included. The GIQLI score was significantly better in patients on a gluten-free diet (GFD) than in non-treated patients on their usual diet, both in terms of the overall score (3.3 vs 2.7, respectively; P < 0.001), as well as on the individual questionnaire dimensions. Both the preference value of the EQ as the visual analogue scale were significantly better in treated than in non-treated patients (0.93 vs 0.72 P < 0.001 and 80 vs 70 P < 0.001, respectively). Variables significantly associated with a worse HRQOL score were female gender, failure to adhere to a GFD, and symptomatic status.CONCLUSION: In untreated celiac disease, the most important factors that influence patient perception of health are the presence of symptoms and a normal diet. HRQOL improves to levels similar to those described in the general population in celiac disease patients well controlled with a GFD.

The Combined Effect of Initial Error and Model Error on ENSO Prediction Uncertainty Generated by the Zebiak-Cane Model

Initial errors and model errors are the source of prediction errors. In this study, the authors compute the conditional nonlinear optimal perturbation （CNOP）-type initial errors and nonlinear forcing singular vector （NFSV）- type tendency errors of the Zebiak-Cane model with respect to El Nifio events and analyze their combined effect on the prediction errors for E1 Nino events. The CNOP- type initial error （NFSV-type tendency error） represents the initial errors （model errors） that have the largest effect on prediction uncertainties for E1 Nifio events under the perfect model （perfect initial conditions） scenario. How- ever, when the CNOP-type initial errors and the NFSV- type tendency errors are simultaneously considered in the model, the prediction errors caused by them are not am- plified as the authors expected. Specifically, the predic- tion errors caused by the combined mode of CNOP-type initial errors and NFSV-type tendency errors are a little larger than those caused by the NFSV-type tendency er- rors. This fact emphasizes a need to investigate the opti- mal combined mode of initial errors and tendency errors that cause the largest prediction error for E1 Nifio events.

Mixed Gl2／GH2 multi-channel multi-objective control synthesis for discrete time systems

This paper proposes a new approach for multi-objective robust control. The approach extends the standard generalized l2 (Gl2) and generalized H2 (GH2) conditions to a set of new linear matrix inequality (LMI) constraints based on a new stability condition. A technique for variable parameterization is introduced to the multi-objective control problem to preserve the linearity of the synthesis variables. Consequently, the multi-channel multi-objective mixed Gl2/GH2 control problem can be solved less conservatively using computationally tractable algorithms developed in the paper.

Reductive amination of ketones with ammonium catalyzed by a newly identified Brevibacterium epidermidis strain for the synthesis of(S)-chiral amines

The asymmetric reductive amination of achiral ketones with ammonia is a particularly attractive reaction for the synthesis of chiral amines.Although several engineered amine dehydrogenases have been developed by protein engineering for the asymmetric reductive amination of ketones,they all display(R)‐stereoselectivity.To date,there is no report of an(S)‐stereoselective biocatalyst for this reaction.Herein,a microorganism named Brevibacterium epidermidis ECU1015 that catalyzes the(S)‐selective reductive amination of ketones with ammonium has been successfully isolated from soil.Using B.epidermidis ECU1015 as the catalyst,the asymmetric reductive amination of a set of phenylacetone derivatives was successfully carried out,yielding the corresponding(S)‐chiral amines with moderate conversion and>99%enantiomeric excess.

The Difference between ZSM-5 Zeolites Manufactured from Various Synthesis Systems and Their Catalytic Performances

ZSM-5 zeolites with similar St/Al ratio were synthesized successfully using various templates [n- butylamine （BTA）, tetrapropylammonium bromide （TPABr） and no template （NT）] under hydrothermal conditions, The samples were characterized by XRD, SEM, Py-IR and BET surface area measurements in order to understand the template eiTects and the differences between the ZSM-5 santples. The synthesis of ZSM-5 with organic templates was relatively easier than those with inorganic templates and withnut template. SEM results revealed that ZSM-5 synthesized with different templates had different morphologies in similar particle size. Toluene disproportiortation reaction was carried out over the catalyst samples to evaluate the catalytic properties. The results have shown that large crystals which have a correspondingly small external surface showed a high para-xylene selectivity, and the amount of C9^＋ and C5^＋ was much less than that obtained from zeolite with small crystals.

Strong/weak limits and strong/weak differentials of multi-variable indeterminate forms. II: Supplementary annotations and analysis

Supplementary annotations on special forms 1to 4, discussion on the general characteristics of K(t) and K(t, t), and analyses on two noticeable limits are presented in this part. It is demonstrated that strong and weak parabolic transforms can be employed to change the standard form of a multi-variable indeterminate form into xmK type, hence to derive the standard formulae of the limit and the differential.

Successful Delivery of Infrastructural Projects： Epistemic Overview of Cost Risk and Uncertainties

The process of decision making and risk analysis are essential tasks along the construction project cycle. Over the years, construction practitioners and researchers have used various methods, tools and techniques to evaluate risk and assist in making more concise decisions. Most practitioners, however, rely on their expert judgment, past experience, intuition, acquired and accumulated knowledge and gut feelings to make decisions. Aleatory （natural, heterogeneity and stochasticity） and epistemic （subjective, ignorance） are the two major types of uncertainties observed in natural sciences. Practitioners traditionally deal with aleatory uncertainty through probabilistic analysis based on historical data （frequentist approach）; and epistemic uncertainty, on the other hand, handled through the Bayesian approach which has limitations since it requires a priori assumption. This paper reports the application of the DST （Dempster Shafer Theory） of evidence to determine the most critical risk factors affecting project cost contingencies using their epistemic probabilities of occurrence. The paper further discuses how these factors can be managed to enhance successful delivery of infrastructural projects. It uses the mixed methodology, with data gathered through structured questionnaires distributed to construction clients, contractors, professionals and experts in the built environment. The research revealed that design risk, financial risk and economic risk were most important cost risk categorizations. In particular, scope changes, incomplete scope definition, incomplete design, changes in specification, micro and macroeconomic indicators and delayed payment problems were identified as the most important risk factors to be considered during the cost contingency estimation process, hence successful delivery of infrastructural projects. The paper concludes by recommending modalities for managing the contingency evolution process of risk estimation to enhance successful delivery and management of infrastructural projects.