Computer simulations of “realistic” partially anisotropic microstructures statistically similar to real microstructures

An image processing based technique is presented for geometric simulations of anisotropic/partially-anisotropic microstructures that have specified morphological anisotropy via its application to the microstructures of TiB whiskers in a Ti–6Al–4V–1.0B alloy. Simulations utilize realistic complex feature morphologies/shapes and generate microstructures having specified volume fraction, size distribution, morphological anisotropy, two-point correlations, and lineal path probabilities. The micromechanical response of microstructures generated through this technique is compared to the corresponding real microstructure using finite element computations. The methodology can be used to simulate rational virtual microstructures of materials that have not been processed.     

Guides “bimorphes” d''ondes ultrasoniques “bimorph” ultrasonic wave guides”

An analysis of the dispersion of elastic waves is presented for two types of long ultrasonics wave-guides that we qualify of “bimorph”: (i) a “three-layer” guide made of two different materials and (ii) a “clad core” guide built up of a rectangular core surrounded by a cladding, the materials of the rod and cladding having different properties. An analytical model is proposed to describe the extensional, flexural and torsional motions in “bimorph” wave guides having two geometrical and material symmetry axes. The asymptotic behaviour of the model allows one to select the material properties which lead to modes guided essentially either in the central layer or in the core of the bimorph guide. Moreover, the dispersive properties of a “bimorph” can be controlled through the choice of geometrical and material parameters.     

Antecedents of proactive supply chain risk management – a contingency theory perspective

Since supplier insolvencies are a major source of supply chain disruptions, scholars have continuously suggested managing supply chain risk management (SCRM) proactively in order to avoid their occurrence. However, business practice seems to fail with this task. This paper investigates antecedents which foster proactive SCRM implementation from a contingency theory perspective. As a major contingency we choose past supplier insolvencies as an indicator for the level of vulnerability of organisations and investigate inter-organisational, intra-organisational, and individual antecedents. By consulting supply chain management and management accounting literature, hypotheses are developed and tested via content analysis in 63 interviews with representatives from the automotive industry. The findings demonstrate that a mechanistic management control system, a rational cognitive style and relational buyer–supplier relationships have positive impacts on proactively managing supplier insolvency risks. Furthermore, past experience with supplier insolvencies has a moderating, though not a direct, effect on proactiveness. This research suggests that a holistic risk management approach is required to proactively mitigate supplier insolvency risk.     

Kinetic Modeling of “Go Slow” Dialysis in Acute Renal Failure

Go slow” dialysis is a gentle, intermittent hemodialysis therapy for acute renal failure patients, with advantages compared to slow, continuous therapies. It employs a recirculating closed dialysate circuit. A two-pool urea kinetic model is elaborated to determine kinetic parameters from blood and dialysate concentrations. This will allow quantification of the therapy. Variable clearance is included to accurately describe the kinetic process. The model is tested in an acute renal failure patient. Solute removals, as determined from direct dialysis quantification and by the model, are comparable. Variable clearance is not required to determine the kinetic parameters, because the constant mean clearance delivers equal results. The dialysis dose, as defined, allows comparison with chronic renal therapies. It requires solute removal determined from dialysate sampling and time-averaged concentration (TAC) from the urea kinetic modeling. In the test patient, dialysis dose is lower compared to standard thrice-weekly therapies because of its lower efficiency and higher TAC, a result of his highly catabolic state.     

A New “Contact-Based” First Year Engineering Course*

A new first year, engineering orientation course has been put in place at NCSU. The course stresses integration with other first year courses, writing, team building, critical thinking, disciplinary thinking, and has a strong problem-solving component. Students were randomly selected to participate in the course. Students' attitudes about engineering and the first year experience were assessed using an instrument developed at the University of Pittsburgh and compared with the normal introduction to engineering course. Students in this course were more positive about their learning experience in the first semester, reported a higher satisfaction with all their courses, and were less likely to think that the first year courses were designed to “weed” students out of the program.     

“I Wish that I Belonged More in this Whole Engineering Group:” Achieving Individual Diversity

Engineers need a breadth of experience to enrich the gene pool of ideas from which elegant engineering solutions can be drawn, called “individual diversity.” While performing large ethnographic research studies where hundreds of engineering students were interviewed, we interviewed Inez, a student that epitomizes individual diversity. Inez is unlike most engineers: she is female, multi‐minority, and from a socio‐economically disadvantaged background. Inez's story is told here using “ethnography of the particular,” where the story of a single individual is explored. Inez has persevered through challenges posed by her lack of familiarity with the culture of engineering, her weak high school preparation, and her feelings of being an outsider in engineering. Inez's story demonstrates that the playing field in engineering is still not level, particularly for socio‐economically disadvantaged students. Her story provides a poignant example of the impact of five of Conefrey's cultural myths of science.     

Comments on “Maintenance policies with two-dimensional warranty”

Chen and Popova [Res. Engng Syst. Saf. 77 (2002) 61] discuss maintenance policies for items sold with a two-dimensional warranty. However, their paper fails to give a proper review of the literature and it also contains errors. In this note we first review the relevant literature and then comment on the errors in their analysis.     

Preliminary dust-impact risk study for the “Solar Probe” spacecraft

Solar Probe is a mission currently under study, funded by the NASA's Office of Space Science—Sun–Earth Connection theme. This mission seeks to achieve the first visit to the Sun to explore the physical phenomenon that occurs at close proximity to our star. The mission requires the spacecraft to follow a polar orbit around the Sun with a perihelion of four (4) solar radii. A flyby at this close distance from the Sun will put the spacecraft under extraordinary environmental loads. One of the concerns is the effect that interplanetary and interstellar dust will have on the integrity of the spacecraft. The maximum dust impact velocity is expected to be around 500 km/s. This velocity is well above current experimental capabilities—more than an order of magnitude higher. For this reason, numerical simulations appear to be the best tool to determine the expected level of damage generated by the solar dust on the structural components and instruments of the Solar Probe spacecraft. Presented here are the results of the analysis of the dust environment to be experienced by the spacecraft and the shielding design parameters for different components. The design parameters of various structural components and instruments were used to conduct computer simulations using CTH to study shielding concepts.     

超大抵抗线硐室爆破的工程实践

在硐室掘进过程中 ,由于管理不善 ,其中一条硐室的轴线偏离了设计方位 ,导致药室的最小抵抗线由原设计的 40m增大到实测的 5 7m。抵抗线超过 5 0m的硐室大爆破十分罕见 ,无经验可以借鉴。针对地形起伏变化的情况 ,采取大坡度设计施工主硐与药室 ,掘进坡度最大达 + 172‰ (约 10°)。在工期特别紧张的情况下 ,合理利用已掘进成形的药室形状 ,调整装药结构、装药位置及条形药包的装药量 ,同时加大了条形药室端部药量 ,采用类哑铃形装药结构 ,使超大抵抗线的硐室大爆破获得成功。     

延时时间对地表振动叠加效应的影响

为了得到非电雷管和电子雷管的合理延时时间进而控制地表振速,以厦门抽水蓄能电站的进场通风兼安全洞的延时爆破为背景,通过现场实测数据和理论公式分析了不同延时时间对地表振动叠加效应的影响。根据实测数据,分析了隧道掘进中毫秒延时爆破和半秒延时爆破地表振动波形的叠加效应,可知非电雷管的误差导致毫秒延时爆破中不同段的地表振动波形形成叠加;而半秒雷管虽有误差,但延时时间较大,不同段的振速波形之间相互独立。利用理论计算探讨了本工程中第1段掏槽孔和第2段掏槽孔在不同延时时间下的振动波形叠加情况,给出了叠加振速放大、叠加振速减小和无叠加产生的几种情况。依据理论和实测振速波形的叠加效应,分别提出适合本工程的毫秒延时非电雷管和电子雷管的合理延时时间,可为类似的隧道延时爆破提供借鉴。     

“Connectivity” in urban rivers: Conflict and convergence between ecology and design

“Connectivity” is a key concept for riparian and landscape ecologists and hydrologists, who use it as a measure of natural integrity in a river ecosystem. Urban designers and politicians use the same term to promote human access to riverfronts. Effective riverfront restoration requires reconciliation of these opposing definitions. A solution is to draw upon abstract and symbolic sources, or “cognitive connectivity,” to raise awareness of the complexity of urban river ecosystems and to provide cues for appropriate use of those systems. Examples of effective cognitive connectivity include restoration plans with strong pedagogical components, water museums, and artistic interventions that reveal ecological processes (eco-revelatory design). The use of visual and conceptual connectivity offers hope for harnessing human creative energy in the interest of ecosystem integrity.     

Are cellulose nanocrystals “alien particles” to human experience?

A wide family of cellulose‐based additives are authorized worldwide as fillers and thickening agents in foods, pills, and tablets, and microcrystalline cellulose (MCC) is, among these, the most important one. Since MCC manufacturing is similar to the main production route of cellulose nanocrystals (CNCs), it is reasonable to wonder whether the MCC would contain CNCs as minor components. In this Short Communication, we provide first results about the occurrence of CNCs in MCC, observed by dynamic light scattering and transmission electron microscopy after serial filtrations of MCC suspensions. The incidence of cellulose nanoparticles has been proved in several different trials in our ongoing works on diverse MCC samples, and the nanoparticles isolated showed shape and dimensions similar to those commonly produced by acidic hydrolysis at laboratory level. Therefore, the presence of CNCs in many products is considered as a certainty. The foods and the pharmaceuticals we have been consuming so far do indeed contain traces of CNCs to such an extent that this wide presence in consumed products should be taken into account when considering possible limitations of the use of these nanoparticles in food contact materials manufacture.     

Examining signs of driver sleepiness,usage of sleepiness countermeasures and the associations with sleepy driving behaviours and individual factors

The impairing effect from sleepiness is a major contributor to road crashes. The ability of a sleepy driver to perceive their level of sleepiness is an important consideration for road safety as well as the type of sleepiness countermeasure used by drivers as some sleepiness countermeasures are more effective than others. The aims of the current study were to determine the extent that the signs of driver sleepiness were associated with sleepy driving behaviours, as well as determining which individual factors (demographic, work, driving, and sleep-related factors) were associated with using a roadside or in-vehicle sleepiness countermeasure. A sample of 1518 Australian drivers from the Australian State of New South Wales and the neighbouring Australian Capital Territory took part in the study. The participants’ experiences with the signs of sleepiness were reasonably extensive. A number of the early signs of sleepiness (e.g., yawning, frequent eye blinks) were related with continuing to drive while sleepy, with the more advanced signs of sleepiness (e.g., difficulty keeping eyes open, dreamlike state of consciousness) associated with having a sleep-related close call. The individual factors associated with using a roadside sleepiness countermeasure included age (being older), education (tertiary level), difficulties getting to sleep, not continuing to drive while sleepy, and having experienced many signs of sleepiness. The results suggest that these participants have a reasonable awareness and experience with the signs of driver sleepiness. Factors related to previous experiences with sleepiness were associated with implementing a roadside countermeasure. Nonetheless, the high proportions of drivers performing sleepy driving behaviours suggest that concerted efforts are needed with road safety campaigns regarding the dangers of driving while sleepy.     

Testing control chart subgroups for rationality

One of the key issues in statistical process control (SPC) is the forming ‘rational subgroups’. Rational subgroups are defined as

• 1 Subgroups displaying only random within-variation.
• 2 Subgroups having small within-variation to compare with variation between subgroups.

In a previous paper¹ we developed an approach of choosing the proper subgroup size for control charts for statistical process control. The approach is particularly appropriate for batch industries where some batch-to-batch variation is to be expected and should be accommodated. In this paper we will deal with the question of whether or not subgroups are rational. A randomness test can be used to verify rationality. The measure selected is the ratio of several different variance estimators. An example is provided to demonstrate the application of the measure.     

Nano “Chocolate Waffle” for near‐IR Responsive Drug Releasing System

A majority of the photo‐responsive drug‐delivery systems that are currently being studied require a complicated synthesis method. Here, we prepare a near‐infrared responsive, photothermally controllable, drug‐delivery carrier by a simple mixing and extraction process without the incorporation of toxic chemicals. A blend of doxorubicin (DOX), an anticancer drug, and a phase‐change material (PCM) are loaded onto the mesoporous structure of silica‐coated graphene oxide (GO@MS) to form a waffle‐like structure, which is confirmed by various physicochemical analyses. The cytotoxicity of DOX/PCM‐loaded GO@MS (DOX/PCM‐GO@MS) against HeLa cells is 50 times higher than that of free DOX, and this improved activity can be attributed to the photothermal effectiveness of GO@MS. Additionally, the cytotoxicity and uptake mechanism of the PCM‐based material are analyzed by flow cytometry. Taken together, our results suggest an enormous potential for spatio‐temporal control in photothermally responsive drug‐delivery systems.     

Proper and effective training of a pattern recognizer for cyclic data

A new approach to training backpropagation neural networks for identifying cyclic patterns on control charts is presented. The objectives of this research are to show that building an effective cyclic-pattern-recognition neural network requires proper training strategies and to demonstrate how these strategies, namely, incremental and decremental training, should be applied and how the performance can be improved with additional statistics. A series of experiments were conducted to study the effect of the number of output pattern classes and the effect of noise on network training and performance. Experiments show that reducing the number of output pattern classes to a small number, e.g., four or fewer, does not guarantee effective learning, and that the noise added to the training data should be maintained at a reasonable level to achieve a balanced performance. Further incorporation of harmonic amplitude statistics (HAS) also proved that the proper use of statistics adopted from Fourier analysis can improve the performance of a cyclic-pattern-recognition neural network. This study offers valuable insights as to how to construct and train a back-propagation neural network properly and effectively for detecting cyclic patterns.     

完善评标体系发展招标投标

新近实施的《招标投标法》对工程招标投标工作提出了更高的要求。谰标是工程招标投标的关键,现行的工程评标体系存在评标方法偏重定性、评标专家库、评标委员会不尽合理等缺陷。本文运用多目标模糊决策方法和专家系统实现了评标方法的定量化、程序化;通过偏好分析,提出对评标专家库进行细分,使得评标委员会的组成更加合理,从而最大程序地降低了人为因素的影响,完善了评标体系,为发展工程招标投标进行了有益的尝试。     

Copper electrowinning from acid mine drainage: A case study from the closed mine “Cerovo”

Copper removal from acid mine drainage originating from closed copper mine “Cerovo” RTB Bor, Serbia and containing approximately 1.3 g dm⁻³ of copper and a very small amount of Fe²⁺/Fe³⁺ ions, has been successfully performed by the direct electrowinning method using either a porous copper sheet or carbon felt as the cathode. A cell with a fluidised bed of inert turbulent promoters, also used in this study, may be considered as unacceptable for the purpose view, having a cell voltage between 12 and 14 V.The cells used in the electrowinning experiments were compared in terms of cell voltage, pH and copper concentration. The results showed that it is possible to remove copper successfully from the mine waters with a high degree of electrowinning—higher than 92% and with a satisfactorily average current efficiency (>60%). Depending on the process time and the applied current, a final copper concentration less than 0.1 g dm⁻³ was achieved. The specific energy consumption was approximately 7 kWh kg⁻¹ of deposited copper. A dense copper deposit was obtained when a three-dimensional electrode was used.     

产品识别要素构建方法研究

针对PI构建过程中识别要素如何提炼的问题,将语意差异法与意象尺度法引入PI识别要素构建方法体系中,进行产品外观意象认知研究。通过实验方法进行PI识别要素的提取,并通过PI识别要素提炼的影响因素分析,将其作为识别要素提炼的主要参考依据,最后通过案例验证该方法的合理性。     

High‐Efficiency PbS Quantum‐Dot Solar Cells with Greatly Simplified Fabrication Processing via “Solvent‐Curing”

PbS quantum‐dot (QD) solar cells are promising candidates for low‐cost solution‐processed photovoltaics. However, the device fabrication usually requires ten more times film deposition and rinsing steps, which is not ideal for scalable manufacturing. Here, a greatly simplified deposition processing is demonstrated by replacing methanol with acetonitrile (ACN) as the rinsing solvent. It is discovered that ACN can effectively “cure” the film cracks generated from the volume loss during the solid‐state ligand‐exchange process, which enables the deposition of thick and dense films with much fewer deposition steps. Meanwhile, due to the aprotic nature of ACN, fewer trap states can be introduced during the rinsing process. As a result, with only three deposition steps for the active layer, a CPVT‐certified 11.21% power conversion efficiency is obtained, which is the highest efficiency ever reported for PbS QD solar cells employing a solid‐state ligand‐exchange process. More importantly, the simple film‐deposition processing provides an opportunity for the future application of QDs in low‐cost printing of optoelectronic devices.