上海市北外滩地区城市环境分析及改善策略

上海石库门旧居具有丰富的历史文化内涵.本文从城市设计、旧城改造的角度,对上海市北外滩一个石库门街区地块进行城市环境分析,提出改善策略,并对不同改造模式进行比较分析,以期对城市改造更新有所启示.     

CFRP筋作体外预应力束的简支梁桥设计研究

本文介绍了c筋在预应力混凝土公路梁桥建设中的应用。该桥为整体现浇25m跨径简支梁,采用CFRP筋中的碳绞线(Carbon Fiber Composite Cable)作为体外预应力束。文中论述了设计中应关注的主要问题,运用理论方法和有限元方法对结构作了全面分析,并在造价上与普通预应力混凝土梁桥作了比较。     

Oxidative desulfurization of diesel with TBHP/isobutyl aldehyde/air oxidation system

Oxidative desulfurization of hydrogenation diesel (40 mL) was studied using air as oxidant, tert-butyl hydroperoxide (TBHP) as radical initiator at ambient pressure and moderate temperature in the presence of isobutyl aldehyde. TBHP could accelerate the production of carbonyl radical and its peroxidation. When the molar fraction of TBHP was 5 mmol, the conversion of DBT could reach 96.1% in the present of 20 mmol isobutyl aldehyde and air, which was more than that of 85.5% without initiator. The air was an effective oxidant and acetonitrile was an optimal solvent in this process. The sulfur content of the hydrogenation diesel could be reduced from 403 to 13 ppm (96.8% removed) under the synergistic effect of air, TBHP and isobutyl aldehyde.     

Mechanism study of iron-based catalysts in co-liquefaction of coal with waste plastics

The state and active site of iron-based catalysts in co-liquefaction of coal with low-density polyethylene (LDPE) have been discussed. The catalysts used were sulfur-promoted iron oxides (Fe₂O₃+S), ferrous sulfide (FeS), ferrous sulfate (FeSO₄·7H₂O) and the mineral pyrite (FeS₂). It was found by X-ray photoelectron spectrometry that the active site in the working state of Fe₂O₃+S catalyst was not Fe_1−XS and the main form of sulfur existing in the spent Fe₂O₃+S catalyst was sulfate, followed by sulfite (SO₃²⁻). A finding from autoclave tests was that the ferrous sulfate before and after oxidation treatments showed sufficiently high activity for the co-liquefaction of coal with LDPE. It was concluded that an active site of the iron-based catalysts was sulfate species formed on the catalyst surface during the hydroliquefaction process of coal.     

输电网络长期规划的伪动态临界可行结构匹配法

输电网络的长期优化问题由于其复杂性而一直未能获得令人满意的解决。对此,本文根据工程实际提出了伪动态临界可行结构匹配法,并对规划期内部投资费用的贴现值最小为目标函数建立了相应的数学模型。     

Relay技术在LTE覆盖解决方案中的应用研究

Relay技术作为一项LTE-A关键技术,具有低成本、灵活拓展等优势,能够有效提高LTE网络系统覆盖能力与吞吐效率。重点分析了Relay技术原理、Relay MBSFN子帧实现方式,并结合中国移动LTE现网状况,提出利用Relay实现GSM直放站覆盖场景LTE延伸覆盖的解决方案。通过LTE现网中验证测试,该方案的部署可提升LTE小区边缘覆盖率67%、增加LTE边缘速率129%。     

Effects of water on steam rectification in a packed column

The effects of water on steam rectification, i.e., multi-stage saturated steam distillation, were investigated in a packed column. N-octane-p-xylene and 1,3,5-trimethylbenzene-1,2,4-trimethylbenzene were used as test systems. Both binary systems are nearly ideal systems and insoluble in water, thus the effects of water in steam rectification can be clearly and definitely revealed. Such unpolar organic liquid is named as “oil”. The water/oil at column top can be separated and refluxed at different ratio. Compared with conventional rectification, there are some peculiar phenomena in steam rectification. Water greatly enhances the flooding vapor velocity of the rectification, in addition, water plays a predominant role in pressure drop of the packed bed near flooding point. It is clear that liquid water in the packed bed can promote mass transfer of steam rectification, especially for materials with higher viscosity. In a word, steam rectification can be operated at low temperature with good mass transfer.     

建筑结构工程安全的保障

本文以结构工程发展的时间为线索,论述了工程安全的重要性,并从历史上不安全工程的角度反观对结构工程发展所起的促进作用。     

Tunable Q-factor wavelet transform denoising with neighboring coefficients and its application to rotating machinery fault diagnosis

Fault diagnosis of rotating machinery is of great importance to the high quality products and long-term safe operation.However,the useful weak features are usually corrupted by strong background noise,thus increasing the difficulty of the feature extraction.Thereby,a novel denoising method based on the tunable Q-factor wavelet transform(TQWT)using neighboring coefficients is proposed in this article.The emerging TQWT possesses excellent properties compared with the conventional constant-Q wavelet transforms,which can tune Q-factor according to the oscillatory behavior of the signal.Meanwhile,neighboring coefficients denoising is adopted to avoid the overkill of conventional term-by-term thresholding techniques.Because of having the combined advantages of the two methods,the presented denoising method is more practical and effective than other methods.The proposed method is applied to a simulated signal,a rolling element bearing with an outer race defect from antenna transmission chain and a gearbox fault detection case.The processing results demonstrate that the proposed method can successfully identify the fault features,showing that this method is more effective than the conventional wavelet thresholding denoising methods,term-by-term TQWT denoising schemes and spectral kurtosis.