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91.
简要探讨了企业改制过程中出现的一些深层次问题并提出了相应的解决对策。  相似文献   
92.
This paper built a combined heat and power (CHP) dispatch model for wind-CHP system with solid heat storage device (SHS) aiming at minimizing system coal consumption, and set system demand-supply balance and units’ operation conditions as the operation constraints. Furthermore, robust stochastic optimization theory was used to describe wind power output uncertainty. The simulation result showed that SHS increased CHP peak-valley shifting capability and reduced abandoned wind rate from 12% to 6%, and reduced 5% coal consumption, compared with the original system operation by flexible charging electric power and heating. The payback period of employing SHS in wind-CHP system is far shorter than SHS expected service life.  相似文献   
93.
Graphene-reinforced aluminum (Al) matrix composites were successfully prepared via solution mixing and powder metallurgy in this study. The mechanical properties of the composites were studied using microhardness and tensile tests. Compared to the pure Al alloy, the graphene/Al composites showed increased strength and hardness. A tensile strength of 255 MPa was achieved for the graphene/Al composite with only 0.3wt% graphene, which has a 25% increase over the tensile strength of the pure Al matrix. Raman spectroscopy, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy were used to investigate the morphologies, chemical compositions, and microstructures of the graphene and the graphene/Al composites. On the basis of fractographic evidence, a relevant fracture mechanism is proposed.  相似文献   
94.
Selective functionalization of mesoporous silica nanospheres (MSNs) is crucial for nanoengineering of MSNs. Herein, we have combined “surface-protected etching strategy” and “cationic surfactant assisted etching strategy” to prepare functionalized MSNs with externally attached amino groups. The externally attached NH2 groups endow the catalysts with excellent catalytic performance for nitroaldol reaction between nitromethane and benzaldehyde. In addition, those NH2-MSNs can also be used to support gold nanoparticles, which display very good catalytic performance for reduction of 4-nitrophenol. It can be envisioned that the synthesis protocol developed in this work could also be extended to nanoengineered MSNs, which provides opportunities for nanoreactors design.  相似文献   
95.
Inferentialists about scientific representation hold that an apparatus's representing a target system consists in the apparatus allowing “surrogative inferences” about the target. I argue that a serious problem for inferentialism arises from the fact that many scientific theories and models contain internal inconsistencies. Inferentialism, left unamended, implies that inconsistent scientific models have unlimited representational power, since an inconsistency permits any conclusion to be inferred. I consider a number of ways that inferentialists can respond to this challenge before suggesting my own solution. I develop an analogy to exploitable glitches in a game. Even though inconsistent representational apparatuses may in some sense allow for contradictions to be generated within them, doing so violates the intended function of the apparatus's parts and hence violates representational “gameplay”.  相似文献   
96.
In this study, we investigate travel mode choice behavior between taxi and subway with an emphasis on the influence of traveling convenience. In the first stage, we examine the Origin-Destination(OD) points of Beijing taxi trips and compare these locations with the respective nearest subway station. Statistics reveal several interesting conclusions. First, for approximately 24.89% of all trips, no convenient subway connections exist between the OD pairs. As such, a taxi becomes the only viable choice. Second, for 80.23% of the remaining 75.11%of trips(equivalent to 60.26% of all trips), access distance from either the origin or the destination to the nearest subway station is greater than 500 meters. This phenomenon indicates that walking distance plays an important role in travel mode choice. In the second stage, we examine groups of taxi trips with similar travel distances and travel times to reveal common features. We establish a preference rule in terms of travel distance and travel time.This determines whether an individual driver will take a taxi or the subway, using a pairwise comparison-based preference regression model. Tests indicate that more than 95% of taxi trips can be correctly predicted by this preference rule. This conclusion reveals that traveling convenience dominates the travel model choice between taxi and subway. All these findings shed light on the factors that influence travel mode choice behavior.  相似文献   
97.
周玉兴  谭春燕  刘立明 《河南科学》2011,29(11):1272-1274
通过引入梯度、旋度和散度,得到Green定理的向量形式.  相似文献   
98.
With the development of the social media and Internet, discovering latent information from massive information is becoming particularly relevant to improving user experience. Research efforts based on preferences and relationships between users have attracted more and more attention. Predictive problems, such as inferring friend relationship and co-author relationship between users have been explored. However, many such methods are based on analyzing either node features or the network structures separately, few have tried to tackle both of them at the same time. In this paper, in order to discover latent co-interests’ relationship, we not only consider users’ attributes but network information as well. In addition, we propose an Interest-based Factor Graph Model (I-FGM) to incorporate these factors. Experiments on two data sets (bookmarking and music network) demonstrate that this predictive method can achieve better results than the other three methods (ANN, NB, and SVM).  相似文献   
99.
针对阳光下物体影子变化的过程,分析时序数据确立特定物体所在地。运用三角函数关系与太阳高度角决定公式确立影长决定公式,最小二乘法确立影长变化函数,日期时间已知时使用正午太阳高度角与逆推影长决定公式得特定物体所在地的经度和纬度,仅时间已知使引入半昼长计算公式与简便正午太阳高度角计算公式联立,得到经纬度推算出日期,最后处理视频得到影长变化数据再计算如前,通过视频中特定物体影长的变化确立视频拍摄日期与地点。  相似文献   
100.
目的:比较腹腔镜胃癌根治术与传统胃癌根治术的临床效果。方法:回顾分析2010年10月至2013年10月大理大学附属医院行腹腔镜胃癌根治术及胃癌根治术共103例胃癌患者的临床资料,分析比较两组患者的临床效果。结果:应用腹腔镜组平均出血量为(153.05±11.71)m L,明显少于开腹手术的(278.45±12.65)m L(P<0.05)。腹腔镜组的平均术后恢复肛门排气时间(3.10±0.62)d,低于开腹手术组的(5.58±1.12)d(P<0.05)。腹腔镜组平均术后住院时间为(14.25±2.78)d,明显低于开腹手术的(22.07±3.59)d(P<0.05)。生存率:行腹腔镜手术者1年总生存率94.1%,开腹手术总生存率92.1%(P>0.05)。结论:腹腔镜胃癌根治术具有术中出血少、术后住院天数少、并发症少等优点,治疗效果与开腹手术相当。  相似文献   
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