Schwarz lemma for driving point impedance functions and its circuit applications

In this paper, a boundary version of the Schwarz lemma is investigated for driving point impedance functions and its circuit applications. It is known that driving point impedance function, Z(s) = 1 + c_p(s − 1)^p + c_{p + 1}(s − 1)^{p + 1} + ..., p > 1, is an analytic function defined on the right half of the s-plane. Two theorems are presented using the modulus of the derivative of driving point impedance function, |Z′(0)|, by assuming the Z(s) function is also analytic at the boundary point s = 0 on the imaginary axis with . In the obtained inequalities, the value of the function at s = 1 and the derivatives with different orders have been used. Finally, the sharpness of the inequalities obtained in the presented theorems is proved. Simple LC circuits are obtained using the obtained driving point impedance functions.     

Molybdenum- and vanadium-containing perovskite electrocatalysts for dissociation of H2S

Catalytic operations, achieving considerable energy savings, continue getting wider application especially in clean energy systems. Perovskite materials, owing to their chemical and thermal stability, can be conveniently used as catalysts and electrode materials at wide temperature ranges. Hydrogen sulfide (H₂S) offers a new and abundant source of hydrogen, the ultimate energy carrier. In the present work, change in electrical conductivity of catalysts obtained by adding molybdenum (Mo) and vanadium (V) as B to the perovskite structure with lanthanum (La) and strontium (Sr) as A and A′, respectively, has been studied within a temperature range of up to 1100 K. Samples La_0.75Sr_0.25MoO₃ and LaSr_0.5V_0.5O₃ demonstrated the highest values of conductivity at 1100 K. At lower temperatures, Cr-added Mo and V catalysts La_0.9Sr_0.1Cr_0.5Mo_0.5O₃ and La_0.9Sr_0.1Cr_0.5V_0.5O₃ had higher conductivity, closely followed by LaSr_0.5V_0.5O₃.     

Reduced configuration set for the multi-step method applied to machine and probe error separation on a CMM

This paper presents a refinement and further analysis of an application of the multi-step method for the separation of machine and probe errors on a CMM using multiple redundancy probing of the machine’s own master ball. The objective is to reduce the amount of data required and so minimize the test time in order to reduce the industrial cost of such periodic verifications.     

Identification of mechanical properties of CuSil-steel brazed structures joints: a numerical approach

In this paper, the inverse method is used to identify the mechanical characteristics of a brazed joint. This technique is based upon tensile tests and/or shearing test combined with the results of a calculation using finite elements method. This paper shows that calculation of a brazed assembly under an elastic behavior assumption is flawed. A correct study of a brazed assembly must be done under an elastoplastic assumption. The presented method will be used for calculation of molds manufactured by stratoconception (sheet metal assembling).     

Risk-opportunity analyses and production peak forecasting on world conventional oil and gas perspectives

To investigate the situation of conventional oil and gas,this paper examines the global oil and gas discoveries,proved reserves,production,consumption and price. All the inuencing factors can be subjected to risk and opportunity analyses,so in the paper,we build upon a risk-opportunity analysis framework,which is a new train of thought. To forecast the peak time of oil and gas production,we used the methods of multi-Hubbert model forecasting and data forecasting. Our results showed that the world oil produc...     

Frequency band characteristics of tree-structured filter banks

A sub-band decomposition filter bank can be recursively used in a tree structure to divide the frequency domain into various subfrequency bands. The frequency bands of the sub-band signals have a counter intuitive order in such a decomposition. The authors show that the relationship between the frequency content and the index of a sub-band signal can be expressed by an extension of the Gray code     

Impact of enhanced geothermal systems on US energy supply in the twenty-first century

Recent national focus on the value of increasing US supplies of indigenous renewable energy underscores the need for re-evaluating all alternatives, particularly those that are large and well distributed nationally. A panel was assembled in September 2005 to evaluate the technical and economic feasibility of geothermal becoming a major supplier of primary energy for US base-load generation capacity by 2050. Primary energy produced from both conventional hydrothermal and enhanced (or engineered) geothermal systems (EGS) was considered on a national scale. This paper summarizes the work of the panel which appears in complete form in a 2006 MIT report, 'The future of geothermal energy' parts 1 and 2. In the analysis, a comprehensive national assessment of US geothermal resources, evaluation of drilling and reservoir technologies and economic modelling was carried out. The methodologies employed to estimate geologic heat flow for a range of geothermal resources were utilized to provide detailed quantitative projections of the EGS resource base for the USA. Thirty years of field testing worldwide was evaluated to identify the remaining technology needs with respect to drilling and completing wells, stimulating EGS reservoirs and converting geothermal heat to electricity in surface power and energy recovery systems. Economic modelling was used to develop long-term projections of EGS in the USA for supplying electricity and thermal energy. Sensitivities to capital costs for drilling, stimulation and power plant construction, and financial factors, learning curve estimates, and uncertainties and risks were considered.     

Designing and operating a pilot plant for purification of industrial wastewater from toxic organic compounds by utilizing solar energy

The aim of the present project was to design and operate a solar reactor system and to analyze its performance for the removal of different types of toxic organic pollutants (e.g., synthetic methyl violet dye and phenol) from water with titanium dioxide as the photocatalyst. Various operating parameters were studied to investigate the behavior of the designed reactor like initial substrate concentration, loading of catalyst, pH of solution, and H₂O₂ concentration. The operating parameters were optimized to give higher efficiency to the reactor performance. Results showed that a photocatalysis system, operating at optimum conditions, offered within one hour of operation degradation up to 95.27% for synthetic dye, while a conversion of 99.95% was obtained in three hours. With phenol, degradation was up to 80.0% and 98.0%, respectively. The removal of TOC for the two toxic materials was also at high levels. This confirmed the feasibility of the designed solar system. The kinetics of dye degradation was first order with respect to dye concentration and could be well described by Langmuir-Hinshelwood model. A preliminary design of a solar photocatalysis system as an alternative treatment method for wastewater effluents from an Iraqi textile mill was introduced.     

Kinetic modeling of liquid generation from oil shale in fixed bed retort

Kinetics of shale oil generation in a fixed bed retort is modeled using a second order rate equation. Samples from Ellajjun oil shale deposits are tested in 350–550 °C temperatures range. In each run, 400 g are charged to reactor and heated in a range of 2.2–10 °C min⁻¹. Shale oil liquid is condensed at 0 ± 2 °C and its rate measured as function of time and temperature.