The potential for low NOx from a precessing jet burner of coal

The effectiveness of the Precessing Jet nozzle at yielding low NO_x levels from burning coal was examined at the pilot scale. Thus, a coal burner of nominal thermal load of 138 kW was sampled two dimensionally, and subsequently modeled. The one-dimensional, steady-state, semiempirical mathematical model considered the release and combustion of volatiles, and subsequent oxidation of char. A comprehensive reaction scheme was formulated to account for the oxidation of the resulting CO, the formation of NO from various sources (volatile, char, preheated air) and the oxidation of H₂S to SO₂. The agreement between the experimental and predicted profiles of coal burnout, [O₂], [NO] and gas temperature was not good near the burner; however, the agreement improved in the postflame region. The model was also used to simulate the center line characteristics of the same flame, but with the secondary air preheated to 500°C. This flame was then scaled for constant velocity and constant residence time to 20 MW. It was deduced that constant residence-time scaling predicts ignition and combustion of the coal at the same axial location as the baseline flame. However, constant velocity scaling shifts combustion closer to the burner. Constant-velocity scaling was found to be more suitable for the theoretical scaling of pulverized coal flames. It was not possible to comment on the potential of the burner for low NO_x in cement kilns, because the measured and computed gas temperatures were low. However, the model predicted low concentrations of fuel NO_x.     

A physical study of plumbing life cycle in apartment houses

We know that extending the life span of a building can reduce environmental impact, and also save money with the viewpoints of life-cycle cost. But due to the complex system construction of buildings, if we apply the concept of life-cycle cost to design, we must consider it in coordination with the life spans of subsystems in order to avoid unreasonable wastage and problems of utility function. Concerning corrosion of piping, past documents mostly direct investigation and analysis to the physical or chemical characteristics of materials. This paper focuses on the plumbing system of a building, by matching up the investigation of practical cases, we determined the life span of a plumbing system in a building and try to offer an assessment system for a life-cycle model. This could be of use in life-cycle architectural planning and design.     

Speech compression and encryption based on discrete wavelet transform and chaotic signals

Multimedia Tools and Applications - To increase transfer and storage efficiencies of the information, data compression has emerged as a significant issue in the communication environments. This...     

Role of Composite Phase Change Material on the Thermal Performance of a Latent Heat Storage System: Experimental Investigation

复合相变材料对潜热储能系统中热性能作用的实验研究

Jasim Abdulateef¹, Ahmed F. Hasan^2*,Mustafa S. Mahdi²

（1. 迪亚拉大学 机械工程系,巴古拜 32001,伊拉克;2.迪亚拉大学 化学工程系,巴古拜 32001,伊拉克）

摘要：

石蜡是可用于潜热储能系统单元（LHSU）的理想的相变材料（PCM）。这种潜热储能单元的使用因相变材料导热性差而受到限制。本文采用铝和相变材料制成的金属泡沫生产复合相变材料,以此作为相变材料-潜热储能单元中的导热材料,并使用水作为传热流体（HTF）。通过实验,评估了使用纯相变材料和复合相变材料的潜热储能单元的传热特性。研究包括熔化和凝固过程中相变材料的时变可视化。此外,热存储室内放置一个热电偶网络,记录每个过程的温度分布。结果表明,复合相变材料-潜热储能单元在熔化和凝固过程中均表现出较好的性能。由于金属泡沫的作用,复合相变材料-潜热储能单元的熔化时间比简单的相变材料-潜热储能单元快83%左右,凝固时间减少85%左右。

关键词：相变材料;金属泡沫;潜热;复合相变材料

     

Influence and Optimization of Surface Roughness on Surface Integrity during Turning Using Grey Relational Analysis

Current machining studies have reported effects of prevalent and common factors, while ultra-high finish requires holistic approach to identify all factors and investigate their effects on machining of hard to machine materials. In this work, a less investigated yet important factor, roughness of the uncut surface, was studied, and its effects on the individual response, i.e., surface finish of the machined part, were found to be significant. AISI 316, which is mainly applied in strategic areas, was selected and three effective turning factors, cutting speed (A), feed rate (B), and roughness of the uncut surface (C) on three output responses including surface roughness of the machined surface (R_a), microhardness(HV), and material removal rate (MRR), were reported. Further, single response optimization of the individual output response and multi-response optimization of all the three responses were carried out. Taguchi L₉ orthogonal array based signal-to-noise (S/N) ratio method was used for individual response optimization, and grey relational analysis (GRA) was employed for multi-response optimization. Effects of the process factors on the output responses were evaluated through inclusive statistical analyses. The individual response optimization revealed that there was a considerable effect of roughness of the uncut surface on the machining performance. Results of the GRA illustrated that the speed during the cutting process and the feed rate had substantial trace on the surface integrity (indicated by R_a and HV) and production rate (indicated by MRR), while roughness of the uncut surface did not have a significant effect.     

Complex multicomponent distillation calculations by continuous thermodynamics

Complex multicomponent mixtures such as petroleum fractions, shale oils, coal-derived liquids etc. are usually characterized by continuous distribution functions which, for example, may be obtained from true boiling point distillations. Current methods for separation calculations, however, are based on the flows of discrete components. Hence, to apply these methods the continuous distributions traditionally are split into a number of pseudo-components. This is a crude and arbitrary procedure. Based on earlier work, the present paper shows how to perform distillation calculations for complex multicomponent mixtures by using the continuous distributions directly without splitting into pseudo-components.     

Economic evaluation of biogas for optimizing generator temperature in a vapour-absorption system

An economic analysis of biogas as a source of energy to the pumpless LiBrH₂O absorption system has been carried out. The generator temperature and pressure, evaporator temperature, precooler and preheater effectivenesses were used as system variables. The optimum generator temperature has been presented graphically for a wide range of operating conditions. Multipliers have also been obtained for evaporator temperatures other than 5°C.     

Efficient sensory-grounded grasp pose quality mapping for gripper design and online grasp planning

The gentle grasping and manipulation of objects in dense un-structured environments, such as the agricultural, food processing, or home environments constitute a formidable challenge for robotic systems. Knowledge regarding wrist poses (wrist positions and orientations) that may lead to successful grasps is especially important in such environments for both gripper design and online grasp planning. Graspability maps store grasp quality grades at different wrist poses in object-centered coordinates. Previously graspability maps were derived based on object models in a lengthy, offline process and thus had limited usability. We have developed geometry-based grasp quality measures related to classical grasp quality measures, which can be determined directly from a 3D point cloud. This facilitates embedding agent perception capabilities within the grasp quality determination. Additionally by scanning the object’s surface for finger contact points rather than scanning the volume of the bounding box about the object, and by using parallel computation, graspability map computation-time is considerably reduced, facilitating online computation of multiple measures. We validate the developed measures in a physical environment, show that computation-time can be reduced by more than 90% with very low reduction in map quality, and show the applicability of the developed methods for both simple and complex objects.     

Erosion-Corrosion of Low-Carbon Steel in the Absence and Presence of Slurry in Saline Water: Kinetic and Mathematical Views

The purpose of this work is to study the combined effect of corrosion-erosion of mild steel in 3.5% NaCl solution as a function of flow rate, angle, sand concentration, and exposure time. Weight loss technique is used to obtain the corrosion-erosion data. The present work is focused on determining the optimum mathematical equation and operating conditions in order to achieve good prediction properties. Three mathematical-kinetics equations were suggested. A computer-aided program was used for developing these models. Results show that the polynomial mathematical equation was able to accurately predict the measured data with high correlation coefficients.     

Optimal Sparse Autoencoder Based Sleep Stage Classification Using Biomedical Signals

The recently developed machine learning (ML) models have the ability to obtain high detection rate using biomedical signals. Therefore, this article develops an Optimal Sparse Autoencoder based Sleep Stage Classification Model on Electroencephalography (EEG) Biomedical Signals, named OSAE-SSCEEG technique. The major intention of the OSAE-SSCEEG technique is to find the sleep stage disorders using the EEG biomedical signals. The OSAE-SSCEEG technique primarily undergoes preprocessing using min-max data normalization approach. Moreover, the classification of sleep stages takes place using the Sparse Autoencoder with Smoothed Regularization (SAE-SR) with softmax (SM) approach. Finally, the parameter optimization of the SAE-SR technique is carried out by the use of Coyote Optimization Algorithm (COA) and it leads to boosted classification efficiency. In order to ensure the enhanced performance of the OSAE-SSCEEG technique, a wide ranging simulation analysis is performed and the obtained results demonstrate the betterment of the OSAE-SSCEEG technique over the recent methods.