上海质子治疗装置慢引出RFKO研究

分析了医用质子加速器慢引出RFKO方法的基本原理,解析了RFKO方法的振幅增长机制;分析了使束流幅度达到一定均匀性的幅度调制(AM)函数模型,导出不同RFKO踢角和引出束流的关系以及为使束流均匀引出,踢角随时间变化的关系。运用软件WinAGILE模拟初始粒子动量分布与引出束流分布的关系,tune值偏差及共振驱动六极磁铁与引出束流的关系。     

Slow burst testing of samples as a method for quantification of composite cylinder degradation

The current practise to focus periodic retesting of composite cylinders primarily on the hydraulic pressure test has to be evaluated as critical. The test itself always causes a certain amount of micro damage to the cylinders but does not necessarily deliver sufficient and evaluable information. Thus BAM Federal Institute of Materials Research and Testing (Germany) moves the focal point to a new approach for validation of composite cylinders, based on destructive sample tests parallel to operation. Statistical assessment of results of these destructive tests is employed for the estimation of remaining safe service life, based on reliability demands. The estimated service life is also used for the determination of re-test periods of the examined population of composite cylinders.An essential aspect of this approach is the validation of current residual strength and its prediction at any point of service life. In cases of gas cylinders with very high cycle strength, residual strength cannot be quantified statistically by means of hydraulic load cycles. As a replacement, creep tests or burst tests may be employed. BAM suggests the “slow burst test SBT” as a combination of these two test procedures. This is a compromise between the practicability of the (conventional) burst test and the practical relevance of sustained loads during service, to be tested in creep rupture tests. In this paper, a variety of 99 burst results of a cylinder design type used for breathing apparatus (CFRP with PE-liner) is evaluated. The influence of test procedure parameters and nature and intensity of artificial ageing on the test sample strength are analysed statistically. This leads to an evaluation of different procedures of artificial ageing and the recommendation to substitute conventional burst tests by slow burst tests for the assessment of composite pressure receptacles.     

Evolutionary approach for crowdsourcing quality control

Crowdsourcing is widely used for solving simple tasks (e.g. tagging images) and recently, some researchers (Kittur et al., 2011 [9] and Kulkarni et al., 2012 [10]) propose new crowdsourcing models to handle complex tasks (e.g. article writing). In both type of crowdsourcing models (for simple and complex tasks), voting is a technique that is widely used for quality control [9]. For example, 5 workers are asked to write 5 outlines for an article, and another 5 workers are asked to vote for the best outline among the 5 outlines. However, we argue that voting is actually a technique that selects a high quality answer from a set of answers. It does not directly enhance answer quality. In this paper, we propose a new quality control approach for crowdsourcing that can incrementally improve answer quality. The new approach is based upon two principles – evolutionary computing and slow intelligence, which help the crowdsourcing system to propagate knowledge among workers and incrementally improve the answer quality. We perform explicitly 2 experimental case studies to show the effectiveness of the new approach. The case study results show that the new approach can incrementally improve answer quality and produce high quality answers.     

Predicting the failure by slow crack growth of SiC-based multifilament tows: Batch-to-batch discrepancies as linked to fiber slack

This work investigates the scale effect observed on slow crack growth parameters for SiC-based fibers (Nicalon® and Tyranno® ZMI) and how it can be affected by the variability from a batch of tow to another one. A 10% difference on the stress exponents (n_t) was numerically estimated using a dedicated Monte Carlo simulation. This effect is however marginal when compared to the lifetime scatter itself. This partly originates from the fiber slack in used tow specimen, assessed by tensile test completing the experimental work. The number of tensile tests to be performed is discussed. Specimen gauge length is an additional and significant source of discrepancies affecting the fiber alignment and subsequently the tow stress exponent.     

Impact of Process Conditions on Digestibility of Pea Starch

This study investigated how process conditions affect the digestibility of pea starch from pea starch powder (PSP). The factors considered were resistant starch (RS), slow digestible starch (SDS) and rapidly digestible starch (RDS) content. The examined five process factors were: material/water ratio, cooking temperature, cooking time, soaking time, and heat dehydration time. Changes in process conditions mainly altered the content of RS and SDS. Analysis with Sephadex G-200 chromatography and differential scanning calorimetry revealed that RS was mainly from retrograded amylose and amylopectin, while SDS and RDS were mainly derived from amylopectin.     

Tailoring the time delay of optical pulse/sequence employing cascaded SOA and band-pass filter

Abstract

A tunable time delay for a 100-ps pulse is achieved via a SOA cascaded band-pass filter, which can be tailored by tuning the filter or changing the SOA injection current. For a single pulse, when the pulse propagates through the cascaded system, a delay of 99.6 ps and an advance of 42.6 ps can be achieved by altering the SOA injection current at two different wavelengths located in the red band and blue band of the filter, respectively. The corresponding tunable delay range is 165 ps, and the maximum delay-bandwidth product (DBP) is 1.65. For an optical sequence, to our knowledge, it is the first time that the time delay is tailored over 145.6 ps corresponding to a DBP of 1.46 by tuning the wavelength from 1556.075 to 1556.955 nm, and 45.2 ps (95.6 ps) advance (delay) by tuning the injection current from 100 to 500 mA at 1556.155 nm (1556.955 nm). The dependence of the time delay on the injection current and filtering configuration has been discussed based on plenty of experiments data. Based on SOA’s fast switching, this device can be used for signal synchronization and bit-by-bit signal processing in a communication system.     

一种新型的慢波多层微带滤波器的设计

利用等效电路分析了一种新型的交指电容加载开环结构，并结合多层结构，利用接地板上的孔耦合设计了一个新型椭圆函数滤波器。这种滤波器不仅尺寸大大减小，而且阻带得到了加宽。理论分析和全波仿真结果一致。     

低水量立式水冷设备自动除垢防垢技术

介绍了利用塑料纽带和传热介质的位能实现自动除垢防垢装置的结构原理和能量分析的理论根据，论述了自动除垢防垢塑料纽带的结构优化研究结果，报道了初次装机工业应用试验的情况和效果。     

Evaluation of stress corrosion resistance and corrosion fatigue fracture behavior of ultra-high-strength P/M Al–Zn–Mg alloy

Quasi-static tensile tests in air and slow strain rate tests (SSRTs) in a 3.5% NaCl solution were conducted in an ultra-high-strength P/M Al–Zn–Mg alloy fabricated through powder metallurgy. Attention is also paid to fatigue strength and fatigue crack growth behavior in laboratory air and in a 3.5% NaCl solution. The alloy has extremely high strength of about 800 MPa. However, elongation at break remains small, at about 1.3%. The final fracture occurs by a macroscopically flat crack normal to the tensile axis, with little reduction in area and little shear lip on the periphery of a smooth sample. However, it fails microscopically in a ductile manner, with dimples. Dimple size is less than 1 μm, because the grain size of the alloy is extremely small. Strengthening mechanisms operating in the alloy are: small grains, sufficient metastable η′ phase in a matrix, and intermetallic compound acting as a fiber reinforcement. The SSRT strength in a 3.5% NaCl solution decreases slightly at a very low strain rate, that is smaller than those observed in aluminum alloys sensitive to stress corrosion. This means that the crack initiation resistance to stress corrosion is superior. However, under cyclic loading, the corrosion fatigue strength becomes lower than that conducted in air, because pitting corrosion on a sample surface acts as a stress concentrator. Crack initiation site of quasi-static and fatigue failure of the alloy is at inclusions, and hence, it is essential to decrease inclusions in the alloy for the improvement of the mechanical properties. Fatigue crack resistance of the alloy is inferior to conventional Al–Zn–Mg alloys fabricated by ingot metallurgy, because the fatigue fracture toughness, or ductility, of the alloy is inferior to other Al alloys, and intergranular cracking promotes crack growth. However, no influence of 3.5% NaCl solution on corrosion fatigue crack growth is observed, although an investigation is required into whether stress corrosion crack growth occurs or not, and at the same time, and of corrosion fatigue crack growth behavior at lower stress intensity. The fracture surface and crack initiation sites are closely examined using a high-resolution field emission type scanning electron microscope, and the fracture mechanisms of the alloy are discussed.     

空间行波管耦合结构的设计

对某型号空间行波管的耦合结构进行了理论分析和实用的结构设计，利用HFSS软件对设计的耦合结构的驻波比进行了模拟优化，并通过冷测实验进行了比较验证。比较结果表明，在工作频带内，设计结果和冷测结果取得了很好的一致。