Search

In this work, a variational Bayesian learning-based computation algorithm is developed to “inversely” identify the deformation field of a crashed car and hence their residual strain fields based on its final damaged structural configuration (wreckage), which is important in three-dimensional traffic collision reconstruction and its forensic analysis. Different from our previous Generalized Bayesian Regularization Network (GBRN) algorithm (Xie et al. [2002] Computational Mechanics 69, 1191–1212), the present method is based on Variational Bayesian Learning theory coupled with a Feed-forward Neural Network architecture, and it provides a higher computation efficiency. This is because it requires less number of iterations and produces more accurate registration results, since the locality of nodes are greatly preserved during registration process. In this work, we have demonstrated that the developed machine learning algorithm has a unique capability to practically identify the deformation field of a real crashed car and to recover its initial pre-crash state based on residual damaged geometric configuration, and it shows great potential in forensic analysis of car crash and vehicle crashworthiness evaluation.

Chatbot is a conversational question answering (Q&A) system capable of natural language communication between a computer system and a person. The use of chatbots for 24-hour customer service provides quick responses that solve problems online. This approach is quickly becoming a convenient way for companies to enhance their customer services without location or knowledgeable staff limitations. This research proposes a system framework and develops a prototype virtual reality (VR) enabled transformer mass-customization consultation chatbot. The chatbot technique is a retrieval-based intelligent system. First, thousands of transformer specific frequently asked questions (FAQs) are collected as a Q&A dataset for technical supports retrieval. More than 1.2 million engineering Wikipedia pages and engineering technical papers are used to train a word embedding model used for natural language processing and question-answer retrieval. The chatbot is integrated into a virtual reality (VR) immersive user interface (UI) environment enabling users to make transformer design changes while querying the system about specifications and standards while interacting with 3D models from the company’s knowledge base archive. The system provides two unique UIs for personal computer (PC) and a helmet-based immersive interface. The system supports real-time consultation of mass-customized transformers and their bills of materials (BOM) for design review, analysis and cost estimation.

In this work, the hydrothermal method was used for synthesizing Pt-TiO 2 /graphene nanocomposites. Obtained Pt-TiO 2 /graphene photocatalysts were characterized by Raman spectroscopy, X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, photoluminescence spectroscopy, and UV–vis spectroscopy. The photocatalytic activity of the Pt-TiO 2 /graphene nanocomposite catalyst was assessed by examining the degradation of acid orange 7 (AO7) dye from aqueous solutions as a probe reaction under solar light irradiations. X-ray photoelectron spectroscopy analyses showed that the Pt ions substituted in the TiO 2 lattice were present mainly in the Pt(II) state. Pt-TiO 2 /graphene exhibited higher photocatalytic activities than TiO 2 /graphene under visible light irradiation. The visible light activity of Pt-TiO 2 /graphene was strongly affected by the calcination temperature and the amounts of H 2 PtCl 6 , which were optimal at 500 °C and 10% H 2 PtCl 6 , respectively. The degradation efficiency of the Pt-TiO 2 /graphene nanocomposite was 99% after 6 h of visible light irradiation. The enhanced photodegradation activity might be mainly attributed to the role of Pt-TiO 2 as a charge generating center and graphene played as electron acceptor and transporter in the nanocomposite, which effectively suppressed the charge recombination and promoted the charge transfer within the composite.

In this paper, a meshfree-enriched finite element method (ME-FEM) is introduced for the large deformation analysis of nonlinear path-dependent problems involving contact. In linear ME-FEM, the element formulation is established by introducing a meshfree convex approximation into the linear triangular element in 2D and linear tetrahedron element in 3D along with an enriched meshfree node. In nonlinear formulation, the area-weighted smoothing scheme for deformation gradient is then developed in conjunction with the meshfree-enriched element interpolation functions to yield a discrete divergence-free property at the integration points, which is essential to enhance the stress calculation in the stage of plastic deformation. A modified variational formulation using the smoothed deformation gradient is developed for path-dependent material analysis. In the industrial metal forming problems, the mortar contact algorithm is implemented in the explicit formulation. Since the meshfree-enriched element shape functions are constructed using the meshfree convex approximation, they pose the desired Kronecker-delta property at the element edge thus requires no special treatments in the enforcement of essential boundary condition as well as the contact conditions. As a result, this approach can be easily incorporated into a conventional displacement-based finite element code. Two elasto-plastic problems are studied and the numerical results indicated that ME-FEM is capable of delivering a volumetric locking-free and pressure oscillation-free solutions for the large deformation problems in metal forming analysis.

In this paper, a multi-scale meshfree-enriched finite element formulation is presented for the analysis of acoustic wave propagation problem. The scale splitting in this formulation is based on the Variational Multi-scale (VMS) method. While the standard finite element polynomials are used to represent the coarse scales, the approximation of fine-scale solution is defined globally using the meshfree enrichments generated from the Generalized Meshfree (GMF) approximation. The resultant fine-scale approximations satisfy the homogenous Dirichlet boundary conditions and behave as the "global residual-free" bubbles for the enrichments in the oscillatory type of Helmholtz solutions. Numerical examples in one dimension and two dimensional cases are analyzed to demonstrate the accuracy of the present formulation and comparison is made to the analytical and two finite element solutions.

Continuous reduction of toluene vapours in a gas fluidised bed photoreactor was studied using TiO2-coated activated carbon (AC/TiO2) particles as the fluidising media. The toluene vapour concentration before treatment was in the range between 200 and 1000 ppm and was relatively high compared to previous similar research works. The experimental results showed that the effective toluene reduction duration (according to the Standards of Permissible Exposure Limits of Toluene in Taiwan) was improved for approximately 130–137% using AC/TiO2 particles as the fluidising media compared to that using AC particles as the fluidising media in the fluidised bed photoreactor with the gas flow rate between 3 and 15 L/min. When the gas stream with the toluene vapour concentration 200 ppm, the relative humidity 30% and the flow rate 3 L/min was deducted in the fluidised bed photoreactor using AC/TiO2 particles as the fluidising media, the conditioned gas could pass the toluene permissible exposure limit in Taiwan for more than 11 h.

Both thoracic epidural analgesia (TEA) and i.v. lidocaine were able to decrease postoperative pain and duration of ileus. We compared TEA and i.v. lidocaine (IV) regarding their effects on cytokines, pain and bowel function after colonic surgery.Sixty patients were randomly allocated to one of the three groups. TEA group had lidocaine 2 mg kg(-1) followed by 3 mg kg(-1) h(-1) epidurally and an equal volume of i.v. normal saline. The IV group received the same amount of lidocaine i.v. and normal saline epidurally. The control group received normal saline via both routes. These regimens were started 30 min before surgery and were continued throughout. Blood cytokines were measured at scheduled times within 72 h.Both TEA and IV groups had better pain relief. The total consumptions using patient-controlled epidural analgesia were 81.6 (6.5), 55.0 (5.3) and 45.6 (3.9) ml (P0.01) and the times of flatus passage were 50.2 (4.9), 60.2 (5.8) and 71.7 (4.7) h (P0.01) in the TEA, IV and control groups, respectively. The TEA group exhibited the best postoperative pain relief and the least cytokine surge. The IV group experienced better pain relief and less cytokine release than the control group.The TEA lidocaine had better pain relief, lower opioid consumption, earlier return of bowel function and lesser production of cytokines than IV lidocaine during 72 h after colonic surgery; IV group was better than the control group.

Silicon carbide nanorods with a typical diameter of about 20 nm and a length ranging from 100 nm to a few microns have been formed by rapid thermal processing (RTP) of thin films containing a mixture of carbon and iron over silicon wafers at temperatures ranging from 1000 to 1200 °C. It is proposed that SiC nanorods were formed by solid–liquid–solid process of Si and C with Fe as catalyst. The controllability offered by RTP is crucial as field emission study showed that the turn-on field of the SiC nanorods was a strong function of their length and number density.

The surface plasmon energy of gold clusters formed by Ar + ion beam mixing of Au/silica is investigated for the size effect. The redshift with decreasing cluster size is assigned to the ‘spillout’ effect in small clusters ( 5 nm), assisted with annealing treatment. The competition between ‘spillout’ effect and the frequency dependence of interband dielectric function leads to a quasiquenching of the size effects in the optical response.

We report on the structural modifications of carbon nanotubes (CNT) by laser irradiation. In particular, we investigated the transformation of CNT by using Nd:YAG laser operating at 266 and 1064 nm with different energy fluences and number of pulses. After 15 pulses of 266 nm laser irradiation with a laser fluence of 80 and 60 mJ cm−2, transformation of CNT into sub-micron size plates and cauliflower type aggregation of carbon deposits, respectively, were observed. At a fixed laser fluence of 400 mJ cm−2 (1064 nm) transformation of CNT into carbon mass protrusions with progressive sharper aspect ratio was obtained by increasing number of laser pulses. Our investigations demonstrate that a selective area transformation can be controlled by the laser fluence and number of pulses.

The use of Ti x % -C:H coated cutting tools in a specific machining operation improves wear resistance and results in a good machined surface roughness of 7075T651 aluminum alloy. Better performance is attained by optimizing the adhesion between the coating and the substrate, and providing a suitable coating thickness, a high micro-hardness and reduced friction within the cutting zone. This study shows that optimized Ti x % -C:H-coated tools possess great potential for milling operations compared to cermet and uncoated tools. The results indicate that Ti x % -C:H coatings possess excellent wear resistance and produce good machined surface roughness under dry and cutting-fluid milling processes. Furthermore, the excellent cutting performance for Ti x % -C:H coated tools under the dry process can replace cermet-coated tool operations under the cutting-fluid process.

The results of an earlier survey on creepages and clearances in HVDC converter stations are expanded with data from a new survey and on-site interviews at several operating terminals. The changes which have accompanied the development of several additional HVDC transmission systems at higher voltages are illustrated with specific details on external insulation design. A summary of insulation performance and the effectiveness of different maintenance procedures are discussed.

The Taguchi method was employed to analyse and optimise the use of TiCN films on cemented carbide (WC–6Co–10TiC–8TaC) indexable milling cutters with respect to machining conditions. Six variables, i.e. film construction, cutting speed, feedrate, depth of cut, workpiece hardness, and milling type, were considered. The results showed that the film construction was the most dominant variable, with a percentage contribution as high as 46·10% to the overall performance of the milling system. Through statistical calculation an optimal variable combination was obtained, and the optimal film construction was found to be 3 μm TiN + 2 μm TiCN (from the substrate to the surface) rather than 5 μm TiCN alone. The resultant flank wear showed 380 and 280% improvement over the uncoated and 5 μm TiN coated cutters respectively.

With an axial tension-compression testing machine, assessment was made for the tension and fatigue performance of the AISI 1045 steel specimens, with and without coatings. The coatings had single- and multilayer constructions and ranged from 3 to 9 μm. The fracture mechanisms were examined utilizing a scanning electron microscope (SEM) and an optical microscope. It was found that the application of surface films did not affect the Young's modulus, yield points and tensile strength, but did lower the fracture strain. For fatigue, the multilayer coatings showed poorer enhancement in the fatigue limit than the single layer coatings. With 3 μm single layer TiN a largest enhancement of 40 MPa in the fatigue limit was achieved. The mechanisms responsible for the tension and fatigue failure of the TiN-coated specimens were shown.

A cylinder-on-plate reciprocated sliding testing machine and a tension–compression testing machine were used to compare the wear, tension, and fatigue performance of specimens with Ti base and Cr base coatings grown by physical vapour deposition. Fracture mechanisms were examined using a scanning electron microscope and an optical microscope. The experimental results show that the Cr base coatings possessed far better wear resistance than the Ti base coatings. The application of surface films did not affect the Young's modulus and yield stress but did decrease the fracture strains somewhat. In the case of fatigue, the application of the surface coatings extended the endurance limit by 20–40 MPa.

An axial tension–compression testing machine was used to compare the tension and fatigue performance of the specimens with and without coatings grown by physical vapor deposition process. The surface morphology of the coating layers was examined utilizing a scanning electron microscope and an optical microscope. It was found that the application of surface films did not affect the Young's modulus and yield points but did little decrease the fracture strain. For fatigue, the application of the surface coatings improved the endurance limit by 20–40 MPa.

A cylinder-on-plate line-contact reciprocated sliding testing machine and a tension–compression testing machine were used to compare the wear, tension and fatigue performance of the specimens with Ti-base and Cr-base coatings grown by physical vapor deposition process. The fracture mechanisms were examined utilizing a scanning electron microscope. The experimental results are as follows: The Cr-base coatings possessed far better wear resistance than the Ti-base coatings. The application of surface films did not affect the Young's modulus and yield points but did little decrease the fracture strains. For fatigue, the application of the surface coatings improved the endurance limit by 20–40 MPa.

The Taguchi method was employed to analyze and optimize titanium carbonitride films on cemented carbide (WC-6% Co-10% TiC-8% TaC) indexable milling cutters with regard to machining conditions. Six variables— the films construction, cutting speed, feed rate, depth of cut, workpiece hardness and milling type—were considered. The results showed that the film construction was the most dominant variable, with a percentage contribution as high as 48.85% to the overall variance of the milling system. Through calculations an optimal film construction was found to be 3 μm TiN + 2 μm TiCN (from the substrate to the top) rather than 5 μm TiCN alone under the conditions specified in this study. The resultant flank wear achieved around 480% and 320% improvement compared with the uncoated and 5 μm TiN coated cutters.

Experiments were carried out, utilizing an axial tension–compression testing machine, to assess the tension and fatigue performance of a TiN-coated material, as compared with the uncoated material. The TiN films of three different thicknesses, namely 3, 5 and 7 μm, were used. The results are described as follows: In the tensile tests, the tensile behavior of the coated and uncoated materials was similar, except for the lower fracture strain of the coated materials. In the fatigue tests, the application of TiN films was positive; the resulting enhancement in the endurance limit was by 20–40 MPa.

By way of the PVD process, different metal-based ceramic coatings can be produced by changing the metal targets and reactive gases. In this report, TiN, TiCN and CrN are comparatively studied with respect to their wear performance, through wear simulation machine, under various experimental conditions. The results show that sliding pairs with CrN coating posses much better wear resistance than the other two Ti-based coatings under both dry and lubricated conditions. The CrN coating is thus a potential candidate for replacing TiN and TiCN in certain applications.

At the present time, TiN coating is widely used to improve wear- and corrosion-resistance of working tools and mechanical components on an industrial scale. Yet application of another ceramic coating, CrN, is still limited in situations mated with Ti-, Cu- and Al-base alloys. Some evidence shows CrN to possess properties superior to TiN. A series of experiments were conducted, through a SRV wear test machine, to assess if CrN had the potential to substitute for TiN as mated with ferrous metal. Studies of characterizations and properties of both ceramic films are also presented in this report. The experimental results indicated that CrN of optimum thickness worked much better than TiN under identical conditions. Thus, CrN is expected to be used as a good substitute for TiN.

The process of plasma-enhanced chemical vapour deposition of AlN thin films on oxidized silicon substrates is characterized by using NH 3 and Al(CH 3 ) 3 as reactants and argon as a carrier gas. Mirror-smooth thin films of AlN are deposited under a wide variety of growth conditions. Growth characteristics are determined as functions of process parameters including substrate temperature, plasma power, reaction pressure, reactant ratio and flow rate reactants. The refractive indices of the films vary between 1.8 and 2.0 depending on the process conditions, which is consistent with the change in the film density. X-ray diffraction and transmission electron micrograph analyses indicate that the deposits prepared below 200°C are amorphous while growth above 400°C produces polycrystalline material.

This paper describes a global science and technology company's experience in optimizing the synergy between a state of the art electrical safety program and process safety management. Process safety management tends to focus on equipment and systems that are directly associated with hazardous manufacturing processes. Electric power, control and data systems may not be directly associated with the process, however the integrity and availability of these electrical systems may be critical and essential for process operations and process safety management. The end user has manufacturing operations throughout the Americas, Europe, and Asia. This case history provides a global perspective on integrating electrical and process safety.

The author presents the operation and maintenance experience from the Adelanto converter station. The period of operation reported covers from June 7, 1986, to December 31, 1988. The performance of the transmission system, control system, and the thyristor valves are discussed. Reliability and availability data are presented. Operating experience indicates that the Intermountain Power Project (IPP) HVDC (high-voltage DC) transmission system is a reliable transmission path bringing electric power from Utah to Southern California. The IPP HVDC system continues to meet reliability requirements. The initial design of the IPP HVDC transmission system incorporated many improved features based on operating experience of earlier systems, particularly the Pacific HVDC Intertie. >

AMHS (automatic material handling system) is gaining more importance in wafer fabs as the demands to automation and WIP management efficiency getting tougher, also as wafers become larger and heavier. Aggressive fab managers have always been trying every effort to drive the fab production over its limit; however, once installed, an AMHS generally has little room for improvement (if any). This paper demonstrates how we tried to improve the existing AMHS at one of Winbond's DRAM fabs under the pressure of extra traffic that was required by an increased production volume that went over its original design capacity. We were able to improve the efficiency a bit by modifying the traffic control logic. The vehicle transportation time was reduced 4.4%, and the average daily waiting time for total transportations was reduced 37.35 hours under the original transportation load. Consequently, the overall AMHS transportation capacity was increased and was able to accommodate the heavy traffic.

Photoluminescence study using the 325 nm He-Cd excitation is reported for the Au nanoclusters embedded in SiO2 matrix. Au clusters are grown by ion beam mixing with 100 KeV Ar+ irradiation on Au [40 nm]/SiO2 at various fluences and subsequent annealing at high temperature. The blue bands above ~3 eV match closely with reported values for colloidal Au nanoclusters and supported Au nanoislands. Radiative recombination of sp electrons above Fermi level to occupied d-band holes are assigned for observed luminescence peaks. Peaks at 3.1 eV and 3.4 eV are correlated to energy gaps at the X- and L-symmetry points, respectively, with possible involvement of relaxation mechanism. The blue shift of peak positions at 3.4 eV with decreasing cluster size is reported to be due to the compressive strain in small clusters. A first principle calculation based on density functional theory using the full potential linear augmented plane wave plus local orbitals (FP-LAPW+LO) formalism with generalized gradient approximation (GGA) for the exchange correlation energy is used to estimate the band gaps at the X- and L-symmetry points by calculating the band structures and joint density of states (JDOS) for different strain values in order to explain the blueshift of ~0.1 eV with decreasing cluster size around L-symmetry point., Comment: 13 pages, 7 Figures Only in PDF format; To be published in J. of Chem. Phys. (Tentative issue of publication 8th December 2004)

This paper presents some of the considerations that went into the decision to replace and re-configure the 1600 MW Sylmar Converter Station of the the Southern Terminal of Pacific DC Intertie (PDCI), USA.

This paper discusses the importance and realizability of the "high-level programmability" concept for wheeled mobile robots. A new high-level mobile robot language, called motion description language (MDL), is proposed. This language has a strong and stable theoretical foundation. The Java-based object-oriented MDL implements the structured robot geometry into its class hierarchy perfectly. The language MDL is not only "a" mobile robot language, but is a strong candidate for "the standard" mobile robot language. This innovation will thrust the mobile robotics field forward to meet the challenges of the new century head on.

Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub x} (2212) powders were synthesized by solid-state reaction, loaded into Ag tubes, and processed into tapes by various combinations of drawing, rolling, and heat treatment. Critical current densities at 4.2 K of greater than 10{sup 5} A/cm{sup 2} were achieved from microstructures consisting of large, highly textured 2212 grains. Optimal microstructures were produced by specific mechanical-working conditions and heat-treatment schedules that incorporated solid-state and partial-melt sintering. The relationships between processing, microstructure, and critical current density will be discussed.

Hexagonal Se shows no indication of a transformation to a metallic, superconducting phase up to 160 kbar. Amorphous Se transforms at about 130 kbar to an unstable metallic, superconducting state which anneals slowly at room temperature toward a non-metallic, non-superconducting phase. Monoclinic Se behaves much like amorphous Se. X-ray diffraction indicates that all samples are in the hexagonal phase after release of pressure.

The 1660 MW HVDC transmission system of the Intermountain Power Project (IPP) is designed to deliver energy from a coal-fired, two-unit generating plant in Delta, Utah, to load centers in southern California, USA. To minimize disturbance to the adjacent AC network and the relatively isolated generating plant, several special control features as well as high short-time and steady-state overload capability are required in the design of the IPP HVDC converter stations. The power system reliability requirements of the Western Systems Coordinating Council (WSCC) on the DC transmission system resulted in the specification of guaranteed reliability and availability requirements. The main features in the design of the main circuit equipment, HVDC controls, and the reliability and availability consideration of the IPP transmission system are presented. >

This letter describes the first system level test vehicle in Josephson technology. The experiment consists of four circuit chips assembled on two cards in a high density, 3-dimensional, card-on-board package. A data path, which is representative of a critical path of a future prototype processor, was successfully operated with a minimum cycle time of 3.7ns. The path simulates a jump control sequence and a cache access in each machine cycle. This experiment incorporates the essential components of the logic, power and package portions of a Josephson technology prototype.

Pressure-induced densification and crystallization of vapor-deposited amorphous Se, As, Ge and GeTe were investigated. In general, the density of the amorphous material increases monotonically with pressure and crystallization occurs after a certain pressure level is reached. For each amorphous material there appears to exist an upper density limit beyond which crystallization occurs. The pressure effect on individual substances is correlated to their short-range order and basic structural character.