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The hydrogeological conditions of the piedmont diluvium are one of the key controlling factors for the growth of local vegetation. This paper analyzes the spatial-temporal variation of vegetation in the Golmud River watershed by the linear slope method, Sen’s slope method and Hurst index method based on the hydrogeological division using the MODIS data of NDVI from 2000 to 2018 in the Qaidam Basin on the Qinghai-Tibet Plateau. The results show that the vegetation coverage in the study area is closely related to the hydrogeological conditions, and the hydrogeological unit of the watershed determines the zonal distribution of surface vegetation. Fraction Vegetation Coverage (FVC) is larger in the mountains and fine soil overflow division, but less than 0.1 in the piedmont Gobi, the wetland salt lake and the northern diluvium division. From 2000 to 2018, FVC has improved greatly in the mountains and fine soil overflow division. In the past 20 years, the area of high coverage vegetation in the watershed has nearly doubled, while desert area has been continuously reduced by 20%, these changes mainly occurred in the mountains and fine soil overflow division. The vegetation coverage of degradation is scattered along the southern coast of Dabson Lake, around the Huolanguole River, and around Yuzhu peak. The vegetation of consistent improvement in the future is mainly distributed in the mountains and fine soil overflow division. The vegetation of consistent degradation is mainly distributed around the upper reaches of Holangole River, the upper reaches of Jiaga Riqu, around Yuzhu Peak, and the south bank of Dabson Lake. Meteorological factors are the driving force of continuous improvement of vegetation coverage. This study has scientific significance for local ecological environment protection.

It is the basic task of burn therapy to cover the wound with self-healthy skin timely and effectively. However, for patients with extensive burns, autologous skin is usually insufficient, and allogenic or heterogeneous skin leads to strong immune response. It is vital to choose an appropriate treatment for deep extensive burns. Nowadays, the dermal substitute combined with bone marrow mesenchymal stem cells (BM-MSCs) is a prospective strategy for burn wound healing. Denatured acellular dermal matrix (DADM), as one of dermal substitutes, which prepared by burn skin discarded in escharotomy, not only maintains a certain degree of 3D structure of collagen, but also has good biocompatibility. In this study, the preparation method of DADM was improved and DADM was seeded with BM-MSCs. Then BM-MSCs-seeded DADM (DADM/MSCs) was implanted into mice cutaneous wound, and the effect of DADM/MSCs dermal substitute was assessed on skin regeneration. As a result, BM-MSCs survived well and DADM/MSCs scaffolds significantly promoted wound healing in terms of angiogenesis, re-epithelialization and skin appendage regeneration. DADM/MSCs scaffold may represent an alternative promising therapy for wound healing in deep extensive burns.

An intelligent toolpath (processing sequence) planning for fabricating aircraft structural parts is developed to obtain a minimum-length toolpath while maintaining the required machining time. The problem is first solved in the following ways. Firstly, an abstraction of the machining process is proposed to pick up the feed/retract points of each feature to be machined as the toolpath calculation basis. Secondly, the chaotic simulated annealing method is improved through storing the optimal solution, adding the control condition and selecting each parameter reasonably during the iteration of the algorithm so as to enhance its performance. What’s more, three solution-generating methods are used chaotically to obtain a better result. Lastly, the verification is conducted on four different aircraft structural parts, and the results prove that the proposed algorithm performs very well in terms of toolpath quality and computation time.

In order to enhance the NC programming efficiency and quality of aircraft structural parts (ASPs), an intelligent NC programming pattern driven by process schemes is presented. In this pattern, the NC machining cell is the minimal organizational structure in the technological process, consisting of an operation machining volume cell, and the type and parameters of the machining operation. After the machining cell construction, the final NC program can be easily obtained in a CAD/CAM system by instantiating the machining operation for each machining cell. Accordingly, how to automatically establish the machining cells is a key issue in intelligent NC programming. On the basis of the NC machining craft of ASP, the paper aims to make an in-depth research on this issue. Firstly, some new terms about the residual volume and the machinable volume are defined, and then, the technological process is modeled with a process scheme. Secondly, the approach to building the machining cells is introduced, in which real-time complement machining is mainly considered to avoid interference and overcutting. Thirdly, the implementing algorithm is designed and applied to the Intelligent NC Programming System of ASP . Finally, the developed algorithm is validated through two case studies.

Thermostatic expansion valves (TXVs) have long been used in air-cooled chillers to implement head pressure control under which the condensing temperature is kept high at around 50 °C by staging condenser fans as few as possible. This paper considers how TXVs prevent the chillers from operating with an increased COP at lower condensing temperatures when the chiller load or outdoor temperature drops. An analysis on an existing air-cooled reciprocating chiller showed that the range of differential pressures across TXVs restricts the maximum heat rejection airflow required to increase the chiller COP, though the set point of condensing temperature is reduced to 22 °C from a high level of 45 °C. It is possible to use electronic expansion valves to meet the differential pressure requirements for maximum chiller COP. There is a maximum of 28.7% increase in the chiller COP when the heat rejection airflow is able to be maximized in various operating conditions. The results of this paper emphasize criteria for lowering the condensing temperature to enhance the performance of air-cooled chillers.

This paper presents an effective method of NC machining cutting parameters optimization. For a given machine NC code, we use the secondary development tools provided by VERICUT software, the time series segmentation algorithm of sliding window technique, back stepping method for getting the feed rate based on the empirical formula and other methods to extract, process and optimize the cutting data. As a result of these, we can make the output power of the spindle reaching smooth and get the optimized processing code finally.