Direct and indirect radiative recombination from Ge

Both direct and indirect band gap transitions are observed in Ge by photoluminescence and electroluminescence. The relative emission intensity of direct band gap transition with respect to indirect band gap transition increases with the increase of the n type doping level, optical pumping power, injection current density, temperature, and strain. The enhancement of direct band gap transition is due to the increase of electron population in the direct valley by reducing the difference between direct and indirect band gaps. The reduction of direct and indirect band gaps can be extracted from the emission spectra with direct and indirect transition models. The defects and the thickness dependent reabsorption are responsible for the relatively strong direct band gap transition in the Ge-on-Si sample as compared to bulk Ge.     

Relation between the accuracies of direct and indirect measurements

Translated from Izmeritel'naya Tekhnika, No. 5, pp. 9–10, May, 1988.     

Performance obstacles for direct and indirect labour in high technology manufacturing

Performance obstacles are factors in the work environment that restrict productivity by inhibiting employees in the execution of task responsibilities. In spite of their apparent importance, little research has been done to describe, categorize, or assess these obstacles. A research project carried out in 12 United States electronics firms demonstrates that employees in two groups (circuit board assemblers and manufacturing engineers) view performance obstacles as having a significant influence on their performance. Materials and information obstacles emerged as being the most important to the circuit board assemblers. For the engineers, information and control/authority were the most important obstacle categories. Managers tended to agree with circuit board assemblers about the importance of obstacles for that employee group. However, managers tended to disagree with the engineers, giving lower ratings of importance than the engineers did in several categories. The research provides a step toward a typology of performance obstacles, demonstrating similarities and differences between employee groups and it suggests that at least in some areas managers may not be as accurate as they could be in assessing the influence of performance obstacles on their employees. The findings indicate that the themes that have prevailed in the research on operations management (i.e. materials, quality, scheduling) are viewed by employees as being predominant factors in the productivity equation.     

The direct and indirect effects of corruption on motor vehicle crash deaths

Recent empirical research has found that there is an inverted U-shaped or Kuznets relationship between income and motor vehicle crash (MVC) deaths, such that MVC deaths increase as national income increases and decrease after reaching a critical level. Corruption has been identified as one of the underlying factors that could affect this relationship, primarily by undermining institutional development and effective enforcement schemes. The total effect of corruption can be decomposed into two components, a direct and an indirect effect. The direct effect measures the immediate impact of corruption on MVC deaths by undermining effective enforcement and regulations, while the indirect effect captures the impact of corruption on hindering increases in per capita income and the consequent impact of reduced income on MVC deaths. By influencing economic growth, corruption can lead to an increase or decrease in MVC deaths depending on the income level. Using data from 60 countries between 1982 and 2003, these effects are estimated using linear panel and fixed effects negative binomial models. The estimation results suggest that corruption has different direct effects for less developed and highly developed countries. It has a negative (decreasing) effect on MVC deaths for less developed countries and a positive (increasing) effect on MVC deaths for highly developed countries. For highly developed countries, the total effect is positive at lower per capita income levels, but decreases with per capita income and becomes negative at per capita income levels of about US$ 38,248. For less developed countries, the total effect is negative within the sample range and decreases with increased per capita income. In summary, the results of this study suggest that reduction of corruption is likely a necessary condition to effectively tackle road safety problems.     

Spatial mapping of droplet velocity and size for direct and indirect nebulization in plasma spectrometry

Two novel laser-based imaging techniques centered on particle image velocimetry and optical patternation are used to map and contrast the size and velocity distributions for indirect and direct pneumatic nebulizations in plasma spectrometry. The flow field of droplets is illuminated by two pulses from a thin laser sheet with a known time difference. The scattering of the laser light from droplets is captured by a charge-coupled device (CCD), providing two instantaneous images of the particles. Pointwise cross-correlation of the corresponding images yields a two-dimensional velocity map of the aerosol velocity field. For droplet size distribution studies, the solution is doped with a fluorescent dye and both laser-induced florescence (LIF) and Mie scattering images are captured simultaneously by two CCDs with the same field of view. The ratio of the LIF/Mie images provides relative droplet size information, which is then scaled by a point calibration method via a phase Doppler particle analyzer. Two major findings are realized for three nebulization systems: (1) a direct injection high-efficiency nebulizer (DIHEN); (2) a large-bore DIHEN; and (3) a PFA microflow nebulizer with a PFA Scott-type spray chamber. First, the central region of the aerosol cone from the direct injection nebulizers and the nebulizer-spray chamber arrangement consists of fast (>13 and >8 m/s, respectively) and fine (<10 and <5 microm, respectively) droplets as compared to slow (<4 m/s) and large (>25 microm) droplets in the fringes. Second, the spray chamber acts as a momentum separator, rather than a droplet size selector, as it removes droplets having larger sizes or velocities. The concepts and results presented in this research may be used to develop smart-tunable nebulizers, for example, by using the measured momentum as a feedback control for adjusting the nebulizer, i.e., its operating conditions, its critical dimensions, or both.     

A unified formulation and error estimation measure for the direct and the indirect boundary element methods in elasticity

In this paper, given a boundary value problem for a finite elastic body in two-dimensions, a problem of representing the solution by layers of point forces (F_j) and Somigliana dislocations (B_j) is considered in the infinite homogeneous body that contains the original finite body. In the boundary element method (BEM) solution, either the boundary displacement or traction component at each node is specified, but not both. This provides us a degree of freedom to arbitrarily specify the proportion of the densities F_j and B_j to be used in the direct and the indirect BEM formulations. The nature of the BEM solution errors is identified and a unified error estimation measure with a mesh refinement scheme for both formulations is proposed.     

A method to evaluate direct and indirect design dependencies between components in a product architecture

Methods for evaluating the strength of design dependencies in a product architecture have been widely studied in the literature; however, evaluating the effects of direct and indirect interactions between components/modules remains a challenge. In fact, indirect connections between components/modules are often overlooked in many cases when evaluating design dependencies. Having a more consistent way of defining a product architecture that considers both its direct and indirect connections is important, especially when analyzing redesign complexity and change propagation. In this study, we propose a systematic method to evaluate direct and indirect design dependencies between components in product architectures. Interfaces are classified into six different types based on a thorough review of the literature, and a method for evaluating design dependencies is introduced to estimate the relative importance of interfaces directly from a set of comparable products. Using an electrical circuit analogy, the proposed method can quantify both direct and indirect design dependencies between components within a product architecture. We compare design dependency results for different wireless computer mice to validate the effectiveness of the proposed method. The results show that using the proposed design dependency measure including direct and indirect effects provides more reliable design dependency results.     

露点间接+直接蒸发冷却空调机组节能性分析

介绍露点间接+直接蒸发冷却空调机组节能工况点和一二次风量比以及效率的选择确定,计算机组在不同气候地区能耗和制冷量以及能效比,分析机组的节能性,指出合理的风机风量和风压、水泵流量和扬程以及淋水密度是露点间接+直接蒸发冷却空调机组节能设计的关键环节。为露点间接+直接蒸发冷却空调机组的设计和推广应用提供参考。     

Generalization of the problem of determining the accuracy of direct measurements for achievement of given accuracies in indirect measurements

Using a general statement of the problem, we consider determination of the accuracy required in direct measurements to achieve a given accuracy of indirect measurements related to the direct measurements by some known relationship. A solution to the problem is stated as a theorem and corollaries. Examples are presented to illustrate how the solution obtained here can be applied in concrete cases. Translated from Izmeritel'naya Tekhnika, No. 1, pp. 8–12, January, 1997.     

Reliability-based optimization of direct and indirect LCC of RC bridge elements under coupled fatigue-corrosion deterioration processes

An optimal bridge design should minimize the life cycle cost (LCC) of the structure without compromising its safety. Various cost components need to be evaluated when assessing the life cycle cost of a reinforced concrete bridge. When the structure is subjected to performance degradation due to aging, the probabilistic modeling of degradation is required. In this paper, the reliability-based design optimization RBDO is performed on the life cycle cost of the structure subject to deterioration processes of fatigue and corrosion. This paper advances the state of the art by: considering the coupled corrosion fatigue model in the design optimization and by developing a new approach to evaluate the user delay costs on a bridge, based on direct and indirect costs related to degradation and failure. Also, a sensitivity analysis of optimal costs and design variables is performed. The improved life cycle cost analysis presented herein can be applied to select the optimal design of reinforced concrete bridge elements, by minimizing both agency and bridge user costs, while providing the required safety along the structure lifetime, taking into account the most severe degradation processes.     

Books and Software: Filling in the gaps

A review of Impurities Evaluation of Pharmaceuticals.     

Comparative study of direct and indirect forging processes for rheological material of A356 aluminium alloy

Abstract

Using a vacuum electromagnetic stirring system, a high quality rheological material is developed in order to fabricate the engineering components without defects like internal porosities, which are caused by the entrapment of external air into the melt and impurities arising from the penetration of surface oxides by vacuum electromagnetic stirring. For practical application in vehicle industry, forming of the knuckle component that is used in automobiles was demonstrated by both direct and indirect type rheoforging processes. Here, insufficient filling behaviour occurred during direct forging processes, whereas indirect rheoforging of material with a solid fraction of 30–40% produced a completely formed knuckle component; thus, an indirect forging process may be suitable for forming the knuckle part. Through microstructural investigations and tensile tests before and after T6 heat treatment of the material, mechanical properties were characterised. By obtaining data about the rheoforging process and material properties of the rheoforged product associated with microstructural features, feasibility for future practical application was investigated. Moreover, the die structure for direct and indirect rheological forging processes was comparatively studied.     

Determination of the direct and indirect influences of groove wear and built-up edge on surface roughness in turning by multiple correlation technique

The built-up edge formation in cutting, and the groove wear of the tool, are factors responsible for variation of surface roughness from the ideal value. The significance of these two factors have been studied statistically using multiple correlation technique. The built-up edge, when it is present, is found to affect surface roughness to a greater extent than groove wear.     

A comparative study of the MIG welding of AI/TiC composites using direct and indirect electric arc processes

Metal inert gas welding of Al-1010/TiC/50p composites was carried out on 9 mm thick square bars by applying the electric arc directly and indirectly. Three pre-heating temperatures were used, 50, 100 and 150°C but only direct electric arc (DEA) was applied at room temperature. Welds were microstructurally examined and tested under tensile load. Complete penetration was achieved using both DEA and IEA methods. Uniform welds were obtained using indirect electric arc (IEA), meanwhile broadening was observed in the upper part in DEA welds facilitated by mixture of the base material with the filler. Microstructural observations showed good lateral fusion of the parent composites, little or no dissolution of TiC by IEA and only slight dissolution by DEA, which led to TiAl _x formation during solidification. The presence of Al₄C₃ was not detected. Microhardness weld profiles revealed that the use of IEA reduces the heat affected zone (HAZ). Mechanical failure of the samples was consistently in the weld zone. Mechanical strength in IEA welds (182–186 MPa) was consistent irrespective of the pre-heating conditions and dependant only of the consumable (Al-2024). The mechanical strength of DEA welds was affected to some extent by the incorporation of the reinforcing particles into the weld region and wettability aspects inherent to the welding conditions. The use of IEA seems to be a suitable route for joining Al-based composites even when the reinforcement content is high.     

Ge/GaAs中APD及薄膜性能研究

研究了一种光纤通讯用光电探测器。在ＧａＡｓ上蒸镀８００ｎｍ的Ｇｅ,并在此材料基础上提出了一种吸收倍增分离的雪崩二极管（ＳＡＭ－ＡＰＤ）的结构设计,采用ＧａＡｓ作为倍增区,Ｇｅ作为吸收区。在此结构上初步制作的二极管正向开启电压为０．２￣０．３Ｖ,反向击穿电压为２．５Ｖ,漏电不明显,ｐ－ｎ结特性良好。     

Structural perfection of the GeSi and SiGe heteroepitaxial systems

The structural perfection of heteroepitaxial systems (HESs) of the SiGe type (germanium films deposited onto silicon substrates) and of the “reverse” type (Si films on Ge substrates) has been investigated by X-ray diffraction and metallographical methods. It has been found that the real structures of these HESs are very different. The fragmentation previously observed in the SiGe HES is not found in the reverse system, but thick Ge substrates (d_Ge ～ 1 mm) appear to be plastically deformed throughout their thickness. A mutual correspondence of the damaged areas, inherent in the fragmentary structure (FS) in the SiGe system, is absent in the reverse system. Annealing does not influence the SiGe HES. The nature of the FS and the peculiarities of the deformation of both systems are discussed.     

Determination of intracellular species at the level of a single erythrocyte via capillary electrophoresis with direct and indirect fluorescence detection.

Intracellular contents reflect the specific history of a cell including innate physiological heterogeneity as well as differing levels of exposure to environmental influences. A method capable of analyzing a variety of species from within a single human erythrocyte is demonstrated. Guided by a microscope, individual cells can be drawn into open capillaries of 10-microns i.d. On contact with a low ionic strength buffer solution, the cell lyses and releases its intracellular fluid. The ionic components are then separated by capillary electrophoresis. For glutathione, microderivatization with a fluorescent reagent can be accomplished in vitro with monobromobimane. The effects of extracellular oxidizing and reducing agents on the glutathione levels can thus be followed. For sodium and potassium, or any other ionic species, charge displacement of a fluorescent cation results in indirect fluorescence detection. The two detection modes are suitable for intracellular components present at low-attomole and sub-femtomole levels, respectively.