定制边界滑移平行轴承的挤压效应(英文)

作者最近提出了一种利用滑块入口处的壁面滑移产生流体动压的新型轴承.笔者针对该类新轴承的油膜挤压问题,提出了基于滑移临界剪应力的数学模型,并给出了解析解.结果显示压力分布为分段光滑的抛物线,在滑移/非滑移边界,存在不连续的压力梯度.不同参数条件下的计算给出了不同的压力分布和壁面滑移类型.结果显示,对于代表滑块非浸润区长度的参数xt,最大压力并不总是随参数xt的减小而减小.存在一个参数xt的区间,在该区间内最大压力不变.与经典的挤压膜轴承类似,压力随膜厚的增加或趋进速度的减小而减小.笔者还发现临界剪应力的对挤压效应有重要的影响,揭示了此类新型轴承的一些内在的特性.     

Application of mid-infrared spectroscopy to the development and transfer of a manufacturing process for an active pharmaceutical ingredient

The use of in situ mid-infrared spectroscopy to support the development of a pharmaceutical manufacturing process is disclosed. Data on this two-stage telescoped reaction from several reaction scales (<50 mL to 1600 liters) and at multiple manufacturing locations is shown. In addition to providing data on both reactions in the telescope, the mid-IR data has been used to monitor an intermediate distillation operation and therefore it has been possible to profile the whole process. Data is also shown on aliquot addition during the first chemical transformation, which is used to check the instrumentation.     

Classification of South African red and white wines according to grape variety based on the non-coloured phenolic content

The phenolic content of South African wines was investigated for the purpose of their classification according to variety or cultivar. Twenty-two phenolic compounds were quantified by liquid chromatography in 55 red wines of five varieties and in 38 white wines of three varieties. Data were compared to literature values reported for wines from across the globe. ANOVA was used to determine significant concentration differences between the different varieties. Further grouping of the data was investigated by principal component analysis and cluster analysis. Finally, linear discriminant analysis was used to derive classification functions for the effective recognition of red and white wine varieties which allowed 100.0% and 97.4% correct recognition of red and white wines, respectively.     

Functional expression of horseradish peroxidase in Saccharomyces cerevisiae and Pichia pastoris

The ability to engineer proteins by directed evolution requiresfunctional expression of the target polypeptide in a recombinanthost suitable for construction and screening libraries of enzymevariants. Bacteria and yeast are preferred, but eukaryotic proteinsoften fail to express in active form in these cells. We haveattempted to resolve this problem by identifying mutations inthe target gene that facilitate its functional expression ina given recombinant host. Here we examined expression of HRPin Saccharomyces cerevisiae. Through three rounds of directedevolution by random point mutagenesis and screening, we obtaineda 40-fold increase in total HRP activity in the S.cerevisiaeculture supernatant compared with wild-type, as measured onABTS [2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid)](260 units/l/OD₆₀₀). Genes from wild-type and two high-activityclones were expressed in Pichia pastoris, where the total ABTSactivity reached 600 units/l/OD₆₀₀ in shake flasks. The mutantsshow up to 5.4-fold higher specific activity towards ABTS and2.3-fold higher specific activity towards guaiacol.     

Active cooling of a mobile phone handset

Power dissipation levels in mobile phones continue to increase due to gaming, higher power applications, and increased functionality associated with the internet. The current cooling methodologies of natural convection and radiation limit the power dissipation within a mobile phone to between 1-2 W depending on size. As power dissipation levels increase, products such as mobile phones will require active cooling to ensure that the devices operate within an acceptable temperature envelop from both user comfort and reliability perspectives. In this paper, we focus on the applied thermal engineering problem of an active cooling solution within a typical mobile phone architecture by implementing a custom centrifugal fan within the mobile phone. Its performance is compared in terms of flow rates and pressure drops, allowable phone heat dissipation and maximum phone surface temperature as this is the user constraint for a variety of simulated PCB architectures in the mobile phone. Perforated plates with varying porosity through different size orifices are used to simulate these architectures. The results show that the power level dissipated by a phone for a constant surface temperature may be increased by ～50 - 75% depending on pressure drop induced by the internal phone architecture. Hence for successful implementation and efficient utilization of active cooling will require chip layout to be considered at the design stage.     

The application of wireless local area network technology to the control of mobile robots

This paper describes a communications and control infrastructure for distributed mobile robotics, which makes use of wireless local area network (WLAN) technology and Internet Protocols (IPs). The use of commercial off-the-shelf (COTS) hardware and software components, and protocols, results in a powerful platform for conducting experiments into collective or co-operative robotics. Standard Transmission Control Protocol/Internet Protocol (TCP/IP) compatible applications programming interfaces (APIs) allow for rapid and straightforward development of applications software. Further, the message bandwidth available from WLAN interfaces (1–2 Mbits/s) facilitates multi-robot experiments requiring high data rates, for instance in robot vision or navigation. The infrastructure described is equally applicable to tele-operated mobile robots.     

An extension of Wilkinson's algorithm for positioning tick labels on axes

The non-data components of a visualization, such as axes and legends, can often be just as important as the data itself. They provide contextual information essential to interpreting the data. In this paper, we describe an automated system for choosing positions and labels for axis tick marks. Our system extends Wilkinson’s optimization-based labeling approach to create a more robust, full-featured axis labeler. We define an expanded space of axis labelings by automatically generating additional nice numbers as needed and by permitting the extreme labels to occur inside the data range. These changes provide flexibility in problematic cases, without degrading quality elsewhere. We also propose an additional optimization criterion, legibility, which allows us to simultaneously optimize over label formatting, font size, and orientation. To solve this revised optimization problem, we describe the optimization function and an efficient search algorithm. Finally, we compare our method to previous work using both quantitative and qualitative metrics. This paper is a good example of how ideas from automated graphic design can be applied to information visualization.     

Prototyping flexible touch screen devices using collocated haptic-graphic elastic-object deformation on the GPU

Rapid advances in flexible display technologies and the benefits that they provide are promising enough to consider them for futuristic mobile devices. Current prototyping methods lack facilities to simulate such flexible touch screen displays and the interaction with them. In this paper, we present a technique that provides product developers a tool to interactively simulate products featuring flexible displays, using Augmented Reality and Haptics. This GPU-based algorithm is computationally inexpensive and efficient to deform a polygonal mesh in real time while maintaining an acceptable haptic feedback. The implementation of the algorithm has been found to be successful when applied to a variety of product simulations. This simulation tool can enhance or even replace traditional prototyping and facilitate testing of the prototype at various stages of the design cycle.