Sensitivity analysis of the effects of the thermal parameters of exhaust gases on the output of a thermoelectric generator

Recovering the dissipated heat from exhaust is a useful means of reducing the energy consumption level as well as cutting down on environmental pollution. An efficient technique for recovering this lost heat is the use of thermoelectric generators, which directly convert the dissipated heat into useful electrical energy. In this paper, a whole thermoelectric generator system installed on the exhaust pipe of a vehicle has been modeled, and the effects of thermal parameters on the output of this thermoelectric generator have been measured and evaluated by means of sensitivity analysis. The E‐Fast sensitivity analysis method has been used in this study. The sensitivity analysis results indicate that, among the thermal parameters examined, the temperature of gases entering the heat sink installed at exhaust pipe outlet () has the greatest influence (37%) and the flow rate of fluid entering the heatsink installed on the cold side of thermoelectric modules () has the second greatest influence (17%) on the output power of the considered thermoelectric generator. By using these results, the best cases of hot exhaust gases from various industries and vehicles with the highest potential of recovering the dissipated energy and heat from them by thermoelectric generators can be identified.     

Ionic liquid ultrasound assisted dispersive liquid-liquid microextraction method for preconcentration of trace amounts of rhodium prior to flame atomic absorption spectrometry determination

In this article, we consider ionic liquid based ultrasound-assisted dispersive liquid-liquid microextraction of trace amounts of rhodium from aqueous samples and show that this is a fast and reliable sample pre-treatment for the determination of rhodium ions by flame atomic absorption spectrometry. The Rh(III) was transferred into its complex with 2-(5-bromo-2-pyridylazo)-5-diethylamino phenol as a chelating agent, and an ultrasonic bath with the ionic liquid, 1-octyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide at room temperature was used to extract the analyte. The centrifuged rhodium complex was then enriched in the form of ionic liquid droplets and prior to its analysis by flame atomic absorption spectrometry, 300 μL ethanol was added to the ionic liquid-rich phase. Finally, the influence of various parameters on the recovery of Rh(III) was optimized. Under optimum conditions, the calibration graph was linear in the range of 4.0-500.0 ng mL(-1), the detection limit was 0.37 ng mL(-1) (3S(b)/m, n = 7) and the relative standard deviation was ±1.63% (n = 7, C = 200 ng mL(-1)). The results show that ionic liquid based ultrasound assisted dispersive liquid-liquid microextraction, combined with flame atomic absorption spectrometry, is a rapid, simple, sensitive and efficient analytical method for the separation and determination of trace amounts of Rh(III) ions with minimum organic solvent consumption.     

Simple electromagnetic detection of variations in properties ofmetal surfaces

Recently, a significant improvement in the sensitivity of the nonuniform AC field measurement technique for the detection of cracks was reported. In this paper, the results of the application of the improved technique in the detection of heat-effected zones and ground welds are presented and briefly discussed. In such applications, the use of a long probe is essential     

Thermodynamic analysis of combined diesel engine and absorption refrigeration unit—supercharged engine with intercooling

This paper traces the thermodynamic analysis of a combined supercharged diesel engine with intercooling and an absorption refrigeration unit. Based on thermodynamic laws, the amount of net work, efficiency, and also the amount of cooling capacity available in the exhaust gases, which can be used for engine intercooling or external air-conditioning purposes or both, have been calculated. The influence of the engine configuration and performance parameters on the performance of an ideal system is examined and the acceptable envelope identified. Graphs of net work, efficiency and cooling capacity of the exhaust gases as a function of pressure ratio and temperature ratio of the cycle are given.     

Optimal Routing Policy

We investigate the problem of resource allocation in heterogeneous networks of computational resources. We provide an explicit analytical solution for a situation where the computational environment can be described by M/M/l queueing theory. We illustrate the quality of our solution by comparing results with those obtained via a simple ad hoc resource allocation in large heterogeneous networks consisting of N = 10⁴ nodes with computational resources distributed either uniformly in a given interval, or exponentially in R⁺.     

为升压转换器提供关断功能的外接元件

图1是升压开关转换器电路,它有一个众所周知的问题：如果将升压转换器IC,的输入拉低来关断升压转换器,外接电感L,和正向偏置肖特基二极管D,就可以让负载继续引出电流。对于电池供电的设备来说,这是一个沉重的负载     

In situ observation of crack nuclei in poly-granular graphite under ring-on-ring equi-biaxial and flexural loading

Fracture tests of graphite are known to exhibit sensitivity to stress state, such as a difference between their flexural and tensile strengths. Bi-axial tensile and flexural loading are representative of the stress states in some regions of graphite components in nuclear fission reactors, where loading develops from fast neutron irradiation-induced dimensional change and thermal strains. Study of the behaviour of the inherent defects that determine strength variability requires in situ observation of crack nucleation. To this end, digital image correlation can be used to monitor the evolution of displacement fields and hence the cracks on the surface of large samples whilst under load. In this study, a ring-on-ring flexural test setup was developed to apply equi-biaxial tensile stress to large disc specimens of graphite along with the conventional four-point-bend test. A 17% reduction in mean flexural strength was observed for the equi-biaxial loading, relative to uniaxial loading. DIC was used to characterise the observed fracture nuclei. Linear elastic fracture mechanics analysis was shown to be inadequate to explain the strength reduction. It is suggested that fictitious crack models, originally developed to simulate the behaviour of concrete structures, can be utilised to explain the behaviour.     

Rapid near-field antenna testing via arrays of modulated scatteringprobes

Key results are summarized of efforts to significantly reduce the near-field measurement time by utilizing one- or two-dimensional arrays of modulated scattering probes in lieu of the single probe ordinarily used in conventional near-field measurement techniques. Results of analytical, numerical, and experimental investigations show that the modulated-scattering technique (MST) using arrays of hundreds or even thousands of modulated scattering probes can be used to map the complex near-field of antennas or scatterers in a few seconds or minutes. The results also strongly indicate that classical (nonmodulated) receiving/transmitting arrays can be adapted for rapid near-field data collection. Major factors affecting the accuracy and speed of probe arrays for near-field measurement are delineated and discussed. Experimental results obtained using laboratory prototype MST systems are also presented and discussed     

Correction scheme for continuous rotation of the test antenna using fast near-field measurement techniques

A correction procedure is developed for the case of the continuous rotation of test antenna while performing fast near-field measurements. This general development is vital for the technique of modulated scattering which combines fast electronic scanning through the use of a probe array in one dimension and the rotation of the test antenna for the other dimension. A numerical simulation was performed to check the validity of the correction procedure. The correction procedure is not based on any interpolation scheme.