Conceptual Design for SuperCDMS SNOLAB

Beyond the present dark matter direct detection experiment at the Soudan underground laboratory, the SuperCDMS Collaboration is engaged in R&D activities for a 100-kg scale germanium dark matter experiment nominally sited at SNOLAB (2070 m overburden of rock). The expected sensitivity after 3 years of running is 3×10^?46?cm² for the spin-independent cross section, an order of magnitude improvement over present exclusion limits for WIMP masses ～80?GeV/c². At this depth, and appropriate design of shielding and cryostat, neutron backgrounds will be negligible. The baseline design is an expanded version of CDMS II with Ge substrates (100×33?mm discs) instrumented with the iZIP phonon sensor layout to achieve the electron surface-event rejection power required.     

A New Balanced Design for Eighteen Varieties

A new balanced incomplete block design for v = |8, b = 5|, r = 17, k = 6. λ = 5 is presented. The design is resolvable and can be split into useful partially balanced suhdesigns. When these designs are used for the 2 × 3² factorial experiment they all have factorial structure.     

Design and performance of cryogenic enclosures for long duration testing of large samples

We have designed a large helium dewar as part of an experiment to investigate gravitational radiation. Two such dewars have been constructed. Our use requires a nonmagnetic dewar to cool an aluminium antenna of approximately 5000 kg to below helium temperatures and to keep the antenna in a stable low temperature environment for extended time. This requires a low temperature volume of 1.5 m inner diameter and 3.1 m length and a cooling system capable of efficiently removing the room temperature enthalpy of 8.5 × 10⁸ J. Our solution to this problem is of wider application than simply gravity wave detection so we have discussed the design philosophy in some detail. As constructed, the apparatus uses less than 1 l of helium per hour when cold.     

Modeling of the Transient Particle Velocity Distribution in the Fluidized Bed Combustor (FBC) Riser

ABSTRACT

The geometrical distributions of transient particle velocity in a fluidized bed combustor (FBC) riser are critical to FBC design and manufacturing. Particle image velocimetry (PIV) instrumentation was applied to visualize the particle transient movement in the area of interest (AOI) of an experimental cold model (152 mm ID × 610 mm height) of an FBC. Sixteen (16) PIV particle velocity profiles were generated for the AOI in a 1.6-second time period. A ten (columns) × five (rows) grid was set for each profile. Three levels of fluidizing air velocity were set for the experiments at 2.477 m/s, 2.677 m/s, and 2.823 m/s respectively. A knowledge-based regression method was applied to generate the empirical model of the two-dimensional particle transient velocity with the consideration of four independent variables, x (x coordinate), y (y coordinate), V_g (fluidizing air velocity), and t (time). This model had a data fitting accuracy of 88%. In addition, this model had a very good validation performance with the data obtained from other tests at different experimental setups.

The modeling method is applied for the first time to the particle movement in FBC risers. The research work proved that the design of the experiment and regression analysis are very effective and practical for evaluating experimental conditions and analyzing experimental results in FBC systems.     

Industrial experiences of bending fatigue strength in table liner for cement mill

A table liner for the vertical roller mill has been used to grind natural limestone. Unexpected fatigue failure accidents have occurred during portland cement manufacturing process. The design life of a table liner is 4 × 10⁷ cycles, but the actual fatigue life of a table liner is 2 × 10⁶ to 8 × 10⁶ cycles. The fatigue crack of a table liner initiates from the outside edge of the grinding path of the limestone. When such a crack occurs, the table liner has to be replaced, and this requires 30% of the total maintenance cost of the vertical roller mill. Therefore, this study examines the fatigue failure of a table liner by plane‐bending fatigue test, stress measurement test, finite element analysis and fatigue fracture analysis.     

基于TRIZ/专利规避集成理论的快递无人机载物装置

目的 设计一种结构简单,稳固安全性强,可根据承载物体形状进行快速调整的的快递无人机载物装置。方法 采用TRIZ/专利规避集成理论对快递无人机的载物装置进行创新设计。首先对专利库中的快递无人机载物结构进行专利分析,确定其规避对象为悬吊式无人机载物装置,采用伞形专利组合规避设计方法,建立专利-问题模型确定有用作用和问题作用,确定设计矛盾,运用40条发明原理和76个标准解建立改善后功能模型图,并对其载物装置进行设计。结果 仿真结果表明,创新产品最大工作载荷为225 N,关键部件轨道机翼最大静止状态应力为1.023×10⁷ MPa,飞行状态应力为1.576×10⁷ MPa。载物架最大静止状态应力为1.049×10⁶ MPa,飞行状态应力为2.126×10⁶ MPa。结论 与悬吊式载物装置相比,创新的产品在可载物的形状多样性、稳定性方面更好,更实用、轻便;与吊架托盘式无人机相比,该产品更稳固耐用。     

Determination of critical load for flange buckling in concentrically loaded pultruded columns

Physical testing and theoretical methods to determine the critical local flange buckling load in concentric pultruded columns are presented. Knowledge of this critical load for wide flange profiles is required in a new universal column design procedure. Because there are too few test results for other profile sizes only the standard 203×203×9.53 mm (8×8×3/8 in.) profile is considered. Reasons are given to explain why the 14 data points give buckling loads between 307 and 406 kN. To obtain a test result corresponding to the true physical situation the minimum column length should be four half-wavelengths of the local instability. The true critical load is about 360 kN. Presented are nine closed form equations that can be used to predict the critical load for the local instability. To use these equations effectively, it is shown that the elastic constants of the flange material must be those of the profile being analysed. Numerical methods, and their closed form equations, that include the rotational stiffness at the web–flange connection are shown to be reasonably accurate. However, without direct access to the software they are difficult to apply, and these equations are therefore unsuitable for application in the preparation of universal design guidance. A simpler equation that predicts the buckling load to within 4% of 360 kN is therefore recommended.     

Linking design process to customer satisfaction through virtual design of experiments

This work seeks to better understand how design processes affect design outcomes. Design process data were collected from journals kept as a part of mechanical engineering capstone design projects at Montana State University. Student processes were characterized by time coding journal entries using a 3 × 4 matrix of process variables. The data were modeled using a principal components artificial neural network, and the model used in a virtual designed experiment to obtain estimates for design process factors that significantly affect client satisfaction. Results indicate that greater client satisfaction is achieved through: greater problem definition (PD) activity and idea generation at conceptual design levels, and PD and engineering analysis activities at the system design level. Whereas, design activity at the detailed level associates with lower client satisfaction. These results support some aspects of existing models of “good” design process, and suggest adaptations of the models for novice designers.     

Performance improvement of terrestrial free-space optical communications by mitigating the focal-spot wandering

Abstract

Focal-spot wandering is the main cause for the major power loss in free-space optical communications. Thus,mitigating it is a primary requirement for the successful performance improvement. In order to prove this prerequisite, an experimental set-up using 155-Mbps data transmission is built for the link range of 0.5 km at an altitude of 15.25 m. In the experiment, the receiver is equiped with a control system to stabilize the received optical propagation at the detector plane which is called as focal-spot wandering mitigation control so as to couple the power in bucket perfectly to the photodetector. The performance improvements due to mitigating focal-spot wandering are regressively investigated in terms of various quality assessment key parameters. Maximum radial distance of 0.25 mm, maximum effective scintillation index of 0.17, optical signal-to-noise ratio of 9 dB, minimum eye-opening of ±0.37 V, minimum eye-height of ±0.51 V, controlled bit-error-rate of 6.45 × 10^?9 to 7.09 × 10^?8 and the link margin of 1.83 dB are attained even during strong turbulence level while mitigating focal-spot wandering.     

Determination of lead concentration in Allchar lorandite

The lead/thallium ratio in a sample of Allchar lorandite (Tl·As·S₂) has been measured to be (5.2 ± 1.3) × 10⁻⁶ by means of an alpha activation analysis. The mineral of this mine is expected to be suitable for the geochemical ²⁰⁵Tl solar neutrino experiment.     

MODELLING AND OPTIMIZING OF A MIG WELDING PROCESS—A CASE STUDY USING EXPERIMENTAL DESIGNS AND NEURAL NETWORKS

This paper describes an application of an integrated method using experimental designs and neural network technologies for modelling and optimizing a metal inert gas (MIG) welding process. To achieve optimization, the process parameters must be adjusted in such a way that the deviations from target are minimized while the robustness to noise and to process fluctuations are maximized. This new method consists of an experiment reference template for designing and collecting training data samples, and a parallel distributed computational adaptive neural network system to provide a powerful tool for data modelling and empirical investigations. The relevant data is established using experimental design methods and highlighted in the case study. An adaptive GaRBF neural network is used to approximate the stochastically non-linear dynamics of the welding process to optimize the basic welding parameters. The neural network is trained with welding experimental data, tested and compared in an actual welding environment in terms of its ability to determine weld quality. The results show that the proposed adaptive neural network is capable of mapping the complex relationships between the welding parameters and the corresponding output weld quality. The implementation for this case study was carried out using a ‘semi-automatic’ welding facility, to mass weld a 20″ × 0.438″ pin/box onto a 20″ × 0.5″ × 37′ pipe (tubular drilling products), in an actual workshop which makes oilfield equipment. The entire range of welding combinations that might be experienced during actual welding operations is included to study the weld quality. © 1997 by John Wiley & Sons, Ltd.     

流动注射化学发光体系测定金霉素

本文利用金霉素对KM_nO_4—Na_2SO_3化学发光体系的发光有增敏的作用,结合流动注射技术,建立了流动注射化学发光法测定金霉素的新方法。在最佳条件下,金霉素溶液的浓度在2.0×10~(-7)～5.0×10~(-5)mol/L范围内与化学发光强度呈良好的线性关系。该方法的检测限(S/N=3)为1.0×10~(-8)mol/L。对实际样品进行回收实验,回收率在98%-103%间,结果表明该方法适合对金霉素的测定。并对可能的发光机理进行了初步的探讨。     

电化学发光法测定扁桃酸含量的研究

基于发现的扁桃酸对鲁米诺(Luminol)电化学发光强烈的抑制作用,建立了电化学发光法测定扁桃酸含量的新方法。扁桃酸浓度在8.2×10-8-1.5×10-5mol/L范围内与发光减少值分段呈良好的线性关系。检出限为1.5×10-8mol/L对2.0×10-6mol/L扁桃酸平行测定10次,其相对标准偏差为3.18%。该法具有简便、快速、灵敏的特点,应用于扁桃酸测定,结果满意。     

Determination of thermal properties of dilute LiBr-water solutions

We are developing an absorption air cooling system which can supply 2°C chilled water for air cooling by the usage of dilute solutions of LiBr in water with an evaporating temperature of −6°C as a nonfreezing refrigerant. However, there are few published data for the thermal properties of dilute LiBr water solutions (0 to 30%) below 10°C. In this paper, the freezing temperature and the saturated vapor pressure are reported. The results clearly show the possibility of developing a new type of LiBr absorption refrigerating machine to generate evaporating temperatures below 0°C. To obtain accurate data for the design of this new type of absorption refrigerating machine, an apparatus has been developed to measure the thermal properties of dilute LiBr water solutions below 10°C. The experimental arrangement consists of a cooling bath (340×240×190 mm) filled with fluorocarbon, a glass measuring bottle (ϕ120×100 mm), and an absolute pressure gauge (0–1.3 kPa). The accuracy of the temperature, pressure, and density are within ±0.1°C, 0.01 kPa, and ±0.005%, respectively. Paper presented at the Fourth Asian Thermophysical Properties Conference, September 5–8, 1995, Tokyo, Japan.     

Secondary particle identification using the relativistic rise in ionization

We report on the data analysis and techniques used to determine particle identification from the relativistic rise in ionization as detected by CRISIS, a 1 × 1 × 3 m³, 192 cell, ionization-sampling drift chamber containing an 80% argon/20% carbon dioxide gas mixture. For 100 GeV/c protons/antiprotons (pions) we obtain an ionization FWHM of 7.6% (7.9%), which compares well with the design value of 7.8%. The separation between the mean ionization values for the protons and pions was determined to be 7.9%. We also present the analysis of particle identification for secondary particles produced by interactions in the bubble chamber. A statistical method for correcting for the overlapping ionization curves from secondary protons/antiprotons and pions is discussed.     

Argon ion irradiation effect on Zn nanotubes

The use of ionizing radiation is an effective tool for stimulating a controlled modification of structural and conductive properties of nanomaterials. The paper presents the results of studies of the influence of Ar⁸⁺ ions irradiation with an energy of 1.75 MeV/nucleon with a fluence from 1?×?10⁹ to 5?×?10¹¹ ion/cm² on structural and conductive properties of Zn nanotubes. It was established by scanning electron microscopy, X-ray diffraction and electron diffraction analysis methods that irradiation with Ar⁸⁺ ions makes it possible to modify the crystal structure of nanotubes, increasing their conductivity and decreasing the resistance of nanostructures, without destroying the structure. Zn nanotubes with a diameter of 380 nm were synthesized using the electrochemical synthesis method. An analysis of dislocations density change and stresses in irradiated nanostructures indicates that a deformation in structure and subsequent relaxation of internal stresses are observed. Also, it is shown that as the irradiation fluence increases, an insignificant increase in the parameters of the unit cell is observed, which may be due to an increase in the contribution of thermal vibrations.     

Color Perception in Microgravity Conditions: The Results of CROMOS Parabolic Flight Experiment

The aims of this research are first to verify the actual difference in color perception between conditions in Earth’s (1×g) and parabolic flight’s microgravitational conditions (μg) and to improve the methodology used for data collection, testing the CROMOS software for color sensitivity investigation. Additionally this paper seeks to establish a larger awareness of microgravity vision and its design implications in the field of aerospace engineering. The analysis of variations in color perception between microgravity and 1×g can be applied to a range of fields concerning the space habitat (Fig. 1), the design of information (such as safety notices), or in the space station the analysis of chemical and biological reactions based on chromatography (for example, when subtle color variations are used as indicators in histological cell analysis).     

加工硬化效应对Cu-3.2Ni-0.75Si合金时效组织和性能的影响

利用显微硬度法研究了Cu 3 .2Ni 0 .75Si合金不同时效组织的加工硬化效应对合金组织和性能的影响。研究表明 ,Cu 3 .2Ni 0 .75Si合金中Ni2 Si相的大小和分布对合金时效硬化效应产生显著的影响 ,4 5 0℃×8h时效组织加工硬化效应最大 ,变形量为 80 %时 ,显微硬度增幅在Hv60左右 ;5 5 0℃× 8h时效组织随变形量增加其硬度变化最平缓 ,变形量为 80 %时 ,显微硬度增幅仅为Hv1 0左右。随着变形量的增加 ,合金的导电率缓慢下降 ,80 %变形后 ,4 5 0℃× 4h、4 5 0℃× 8h和 5 0 0℃× 8h的时效组织导电率均下降 6%IACS左右 ,而5 5 0℃× 8h时效组织的导电率变化不大     

Image analysis system for quantitative metallography

This paper describes a Z-80 microprocessor-based image analyzer developed for global parameter evaluation of images over a 256 × 256 pixel frame. It consists of a microscope,ccd scanner, 6-bit videoadc, Z-80 computer and an image display monitor. Facilities are provided for feature erosion/dilation and halo correction. The paper also presents the details of another more powerful user microprogrammable HP1000 minicomputer-based image analysis system under development. This system consists of an optical microscope/epidiascope coupled to a chalnicon scanner. Here the 512 × 512 pixel image is acquired with 8-bit resolution. It provides for shading correction, auto-delineation, image processing and image analysis functions for evaluation of various basic and derived parameters. Both the systems are software intensive and are realised according to requirements of quantitative metallography. They can also be used for analysis of images obtained in the fields of biology, medicine, geological survey, photography and space.     

Structural modification of tantalum crystal induced by nitrogen ion implantation

This paper investigates the effect of nitrogen ion implantation on tantalum surface structure. In this experiment, nitrogen ions which had an energy of 30 keV and doses of 1 × 10¹⁷ to 10 × 10¹⁷ ions cm^?2 were used. X-ray diffraction analysis (XRD) was applied for both the metallic Ta substrate and the study of new structures that have been created through the nitrogen ion implantation. Atomic force microscopy (AFM) was also used to check the roughness variations prior to and also after the implantation phase. The experimental results show the formation of hexagonal tantalum nitride (TaN_0.43) in addition to the fact that by increasing the ion dose, the nitrogen atoms occupy more interstitial spaces in the target crystal. The nitride phase also seen for 3 × 10¹⁷ and 5 × 10¹⁷ ions cm^?2, while it disappeared for higher dose of 7 × 10¹⁷ and 1 × 10¹⁸ ions cm^?2. The FWHM of the dominant peak of tantalum nitride suggest the growth of the crystallite’s size, which is in agreement with the AFM results of the grains.