Study on Dragline-Bulldozer Operation with Variations in Coal Seam Thickness

The dragline is one of the most promising surface mining machines in China. This paper studies the interac-tion between the working bench advancing speed and the stripping volume with variation in coal seam thickness. Ad-justing the bulldozing volume (depth) and/or changing the dragline bench height are proposed as means to ensure a smooth and economical mining operation. When the coal seam is getting thicker it is recommended to reduce the bull-dozing volume (depth) for a higher dragline efficiency. When the coal seam is getting thinner it is recommended to in-crease the bulldozing volume (depth) to ensure the dragline can work at the proper bench height.

Impact of Rising Oil Prices on the Living Cost in Burkina Faso

Fluctuations of the world oil prices affect economic performance. Outside the impact on the sector of energy production, the rising oil price has consequences on inflationary pressures and a deteriorating fiscal position of Burkina Faso. In this context, studying the impact of rising oil prices on the economy, especially the cost of living of its population has a great interest because although many studies have attempted to link 〈〈oil prices〉~ and 〈〈cost of living~, very few have focused on the specific case of Burkina Faso. This allows us to make our contribution to this construction literature. This contribution will consist to highlight the relation between changes in oil prices and the cost of living in Burkina Faso. Also to be reached, we will find the best indicator to reflect the cost of living in Burkina Faso, identify the suitable econometric model for estimating the correlation and verify the existence of the relation between oil prices and the cost of living. For a better approach to this study, we used a VAR （Vector Auto-Regressive） model. Also, we will use documentary research that will make an assessment on the existing in terms of theoretical debates around the theme descriptive statistics that will help to introduce and describe the variables used in the study, and econometric analysis will analyze and estimate the parameters of our objective function using Eviews.

Some Results of Paleozoic Paleomagnetic Research

This application note discusses the preliminary results of paleomagnetics studies of several incisions of the Paleozoic period the territory of Armenia and neighboring regions （Minor Caucasus）. It is supposed that before the Permian period the Armenian-lranian Mezocontinent was uniform with Afro-Arabia and only at the end of the late Paleozoic the formed Mesozoic ocean separated these areas from each other. A result of application of the complex laboratory investigations were identified from samples of primary magnetization the direction of which corresponds to the time of formation of the studied rocks. On the basis of paleomagnetic researches of Triassic, Permian, Devonian, Carbonian rocks a preliminary conclusion has been made about the dipole configuration of the geomagnetic field throughout Paleozoic. The comparison of the obtained data to paleomagnetic definitions of African, Arabian plates, Europe and the Siberian platform leads to the conclusion that the Minor Caucasus existed separately from the present general lithosphere blocks of Greater Caucasus and Europe.

Synchronous bilateral laparoendoscopic single-site urological surgeries via the umbilicus:a report of 2 cases

Objective： To describe two cases of bilateral transumbilical laparoendoscopic single-site（LESS） surgeries in a single operative session and assess the safety, feasibility and efficacy. Methods： One patient underwent right ureterolithotomy and left varicocelectomy, and the patient was performed with right simple nephrectomy for nonfunctioning kidney due to ureteral calculus and left ureterolithotomy using a novel multichannel TriPortTM via a single 2-3 cm transumbilical incision Results： The right-side ureterolithotomy and left-side varicocelectomy were finished in 229 minutes, with a total estimated blood loss of 50 hal. The right-side simple nephrectomy and left-side ureterolithotomy in the other patient were finished in 340 minutes, with a total estimated blood loss of 100 ml. There were no major complications. At the latest follow-up, both patients remained symptom-free and there were no evidences of recurrence. Both of them were delighted for the single scarConclusion： Synchronous LESS urologic procedure via a single umbilical incision is technically feasible, safe and efficacious with a promising potential

Using hot-vapor bypass for pressure control in distillation columns

Distillation column control is widely explored in literature due to its complexity and importance in chemical and petrochemical industries. In this process, pressure represents one of the most important variables to be controlled. However, there are few studies about how pressure affects the dynamic behavior of distillation columns and most research on distillation column control involve direct manipulation of cooling fluid through the condenser. Nevertheless, such an approach demands constant changes in cooling fluid flowrates that are commonly by the order of tons per hour, which can be difficult to work or even unfeasible in a real plant. Furthermore, this strategy is usually avoided, as it can cause fouling and corrosion acceleration. The hot-vapor bypass strategy fits well as a solution for these issues, eliminating the need to dynamically manipulate cooling fluid flowrates in the condensation unit. This work presents the modeling and simulation of a conventional distillation column for the separation of water and ethanol, in which a comparative study between a conventional pressure control and a control using hot-vapor bypass was performed. The main results were obtained through dynamic simulations which considered various disturbances in the feed stream, and demonstrated superior performance by the hot-vapor bypass system over the usual scheme proposed in literature, while evaluating the lntegral Absolute Error （IAE） norm as the control performance index.

翰墨旧事(十四)

一九三七年平型关大捷后，一位青年作家在奔赴摹安的途中，从被日军炸毁的废墟中拾得四册名著及《石索》、《三希堂法帖》各两卷，如获至宝，带到了延安。