Frictional stir Incremental sheet forming (ISF) is a new technology used to fabricate parts of hard-to-form materials without using heating equipment. Thus far, limited information is known about the effects of main forming parameters, except spindle speed of the tool, on the temperature of formed sheet in friction-stir ISF. The effects of six forming parameters, namely, sheet thickness, tool vertical step, tool diameter, spindle speed, feed rate, and wall angle of the formed part, were identified using the design of experiment of orthogonal array, analysis of response tables and graphs, and analysis of variance. Results show that spindle speed, feed rate, sheet thickness, and tool vertical step significantly affect the temperature of the sheet. In addition, the temperature of the sheet is significantly increased by increasing sheet thickness, tool vertical step, and spindle speed but significantly decreased with increasing tool feed rate.
There has been growing interests to reduce the environmental impact caused by greenhouse gas emissions from process plants through various energy conservation strategies. CO2 emissions are closely linked to energy generation, conversion, transmission and utilisation. Various studies on the design of energy-efficient processes, optimal mix of renewable energy and hybrid power system are driven to reduce reliance on fossil fuel as well as CO2 emissions reduction. This paper presents a systematic technique in the form of graphical visualisation tool for cost-effective CO2 emission reduction strategies in industry. The methodology is performed in four steps. The first step involves calculating the energy consumption of a process plant. This is followed by identification of potential strategies to reduce CO2 emissions using the CO2 management hierarchy as a guide. In the third step, the development of “Investment” versus “CO2 Reduction” (ICO2) plot is constructed to measure the optimal CO2 emission reductions achieved from the implementation of possible CO2 reduction strategies. The Systematic Hierarchical Approach for Resilient Process Screening (Wan Alwi and Manan in AIChE J 11:3981–3988, 2006) method is used in the fourth step via substitution or partial implementation of the various CO2 reduction options in order to meet the cost-effective emission reduction within the desired investment limit or payback period (PP). An illustrative case study on a palm oil refinery plant has been used to demonstrate the implementation of the method in reduction of CO2 emissions. The developed graphical tool provides an insight-based approach for systematic CO2 emission reduction in the palm oil refinery considering both heat and power energy sources. Result shows that 31.2 % reduction in CO2 emissions can be achieved with an investment of USD 38,212 and PP of 10 months based on the present energy prices in Malaysia. 相似文献
粉末衍射文件(Powder Diffraction File)是国际衍射数据中心(International Centre for Diffraction Data)编辑、发行的纯化合物X射线衍射数据库。该数据库以表格形式向使用者提供化合物分子式,英文名称,晶系,空间群,晶面间距(d—值),相对强度,晶胞参数和Miller指数等内容。它由原来的印刷卡片发行改为目前的CD-ROM电子版本。截止到1999年底PDF-2数据库共收集约11.5万个化合物衍射数据,而且以每年至少增加1000个以上衍射数据的速度不断扩充。本文对其检索软件和物相定性分析方法也作了介绍。 相似文献
Nonlinear processes involved in the manufacture of nominally sinusoidal surface relief diffraction gratings generated by interference lithography can introduce distortions into the profile of these surfaces. Such distortions may dramatically affect both the specular reflectivity and diffracted efficiencies from such a surface [H. Raether, Phys. Thin Film 9 (1977) 145–261]. We shall consider in particular the case of metallic gratings used to investigate plasmonic effects that can be engineered for bio-sensing applications. To investigate these effects, interference lithography (IL) has been used for the generation of profile controlled sinusoidal plasmonic crystals. IL exposure contrast study has been performed to control the amplitude oscillation and the surface roughness quality. Bi-metallic layer of silver and gold have been systematically deposited with different film thicknesses. A comprehensive numerical model that studies the optical coupling to surface plasmon polaritons on Ag/Au gratings has been undertaken for the simulation of the reflectivity and azimuthal angle dependence [Z. Chen, I.R. Hooper, J.R. Sambles, J. Opt. A: Pure Appl. Opt. 10 (1) (2008) 015007]. This computation illustrates the sensitivity of individual features to specific harmonic components of the surface, for surface plasmon resonances recorded in both the zeroth and higher diffracted orders. The roughness surface control after development and after bi-metallic evaporation strongly contributes to tighten the width of the reflectivity peak. Optimization process has shown that for an Ag (37 nm) and Au (7 nm) metallic bilayer, a semi-amplitude of 20 nm provides the best reflectivity. 相似文献
In safety‐critical scenarios, reliable reception of beacons transmitted by a subject vehicle is critical to avoid vehicle collision. According to the employed contention window sizes in IEEE 802.11p, beacons are transmitted with a small contention window size. As a result, multiple vehicles contend for the shared channel access by selecting the same back‐off slot. This is a perfect recipe for synchronous collisions wherein reliable beacon delivery cannot be guaranteed for any vehicle. We consider the problem of selecting the back‐off slots from the current contention window to provide reliable delivery of beacons transmitted by a subject vehicle to its neighbors. Given a safety scenario, we propose a Pseudo‐Random Number Generator (PRNG)‐inspired back‐off selection (PBS) technique. The proposed technique works on the hypothesis that synchronous collisions of beacons transmitted by a subject vehicle can be reduced if all its neighbors select different back‐off slots (ie, not the back‐off slot selected by the subject vehicle). The discrete‐event simulations demonstrate that PBS can increase the overall message reception from a subject vehicle, in comparison with the uniform random probability back‐off selection in IEEE 802.11p. 相似文献
Properties of pure metals can be enhanced by alloying with other metallic or non-metallic elements according to the need. However, as multiple alloying elements in an alloy may lead to the formation of many intermetallic compounds with complex microstructures and poor mechanical properties, new types of metallic alloys called high entropy alloys with at least five elements with equimolar ratios were developed. In this study, FeNiAlCuCrTixNby (x, y = 0, 0.5, 1.0, 1.5) alloys have been prepared using Ar arc melting technique. Microstructural studies using scanning electron microscope and XRD showed that Ti addition promoted secondary BCC2 phase whereas, Nb acted as FCC stabilizer. Samples with combined Nb and Ti addition showed FCC1 and FCC2 structure with Nb-rich FCC2 dendritic phase as dominant phase. Though, individual Nb and Ti additions have resulted in increased hardness, combined additions have resulted in highest hardness of 797 HV under 1 kg load. 相似文献