Development & research of double loop thermosyphon air-air cooler for wind power generator

Paper presented at the 8th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Mauritius, 11-13 July, 2011.Wind energy is well recognized as the nearest commercialized renewable energy technologies besides the water resource, it has high priority by governments, is developing rapidly worldwide. In the field of wind power, single megawatt wind power unit is becoming the mainstream of technology development and market demand [1]. On the one hand it is needed to optimize the generator structure to reduce heat generation [2], more importantly, efficient cooling system is needed to protect the generator [3]. Air-water cooled and air-air cooled are the main cooling mode for wind power generator coolers. For the air cooled type, most of the current application has simple smooth tube bundle structure, it is larger in size and heavier in weight, it has higher energy consumption and sometimes unable to meet the cooling requirements during hot summer. Lightweight design is the trends, a new type thermosyphon air cooled heat exchanger is developed, compared with the conventional one, preliminary studies indicate that it is about 29% smaller in size, 13.4% lighter in weight, 16.3% saved in energy consumption and 14.6% improved in cooling capacity.mp201

Modeling and dynamic analysis of spiral bevel gear coupled system of intermediate and tail gearboxes in a helicopter.

The coupled dynamic model of the intermediate and tail gearboxes’ spiral bevel gear-oblique tail shaft-laminated membrane coupling was established by employing the hybrid modeling method of finite element and lumped mass. Among them, the dynamic equation of the shaft was constructed by Timoshenko beam; spiral bevel gears were derived theoretically by the lumped-mass method, where the effects of time-varying meshing stiffness, transmission error, external imbalance excitation and the like were considered simultaneously; laminated membrane coupling was simplified to a lumped parameter model, in which the stiffness was obtained by the finite element simulation and experiment. On this basis, the laminated membrane coupling and effects of several important parameters, including the unbalance value, tail rotor excitation, oblique tail shaft’s length and transmission error amplitude, on the system’s dynamic characteristics were discussed. The results showed that the influences of laminated membrane coupling and transmission error amplitude on the coupled system’s vibration response were prominent, which should be taken into consideration in the dynamic model. Due to the bending-torsional coupled effect, the lateral vibration caused by gear eccentricity would enlarge the oblique tail shaft’s torsional vibration; similarly, the tail rotor’s torsional excitation also varies the lateral vibration of the oblique tail shaft. The coupled effect between the eccentricity of gear pairs mainly hit the torsional vibration. Also, as the oblique tail shaft’s length increased, the torsional vibration of the oblique tail shaft tended to diminish while the axis orbit became larger. The research provides theoretical support for the design of the helicopter tail transmission system

Experiment study of multi-fans cooling module using different shroud structures for advanced vehicle thermal management system

As one of the most important components of the vehicle thermal management system, multi-fans cooling module can potentially be used to optimal the system performance in order to save the energy consumption and reduce the vehicle fuel consumption. In this study, a test rig has been designed, constructed and used to test the heat transfer performance of the multi-fans cooling module using four different fan shroud structures. Results indicate the separated plates, which have limited or worse effect on the performance of the system, are not recommended to be used in the multi-fans cooling module. The optimal shroud structure for multi-fans cooling module has been identified and experimentally tested. By adding shutters at the ventilation part of the fans (Shroud C) can significantly improve the overall performance of the module (Shroud A) by 13.25 % to 69.08 % under various operation conditions

Experimental and numerical investigation of rubber damping ring and its application in multi-span shafting

A new approach for establishing the mechanical model of the rubber damping ring was studied numerically and experimentally. Firstly, parameters of Mooney–Rivlin and Prony series models of the rubber material were identified based on ISIGHT integrating with ANSYS and MATLAB, in which the rubber damping ring’s hysteresis loop was obtained by vibration experiment and ANSYS simulation, respectively; meanwhile, the dynamic stiffness and damping were calculated simultaneously by a parameter separation and identification method. Subsequently, the accuracy of the constitutive model parameters was verified experimentally. In the light of this, based on the experimental design and the approximate model method of the joint simulation platform, a mechanical model of dynamic stiffness and damping of the rubber damping ring was established. Finally, the rubber damping ring’s mathematical model was employed to perform a vibration reduction analysis in a multi-span shafting, where the numerical and experimental investigation was conducted, respectively. The results show that the theoretical and experimental error of vibration reduction rate is less than 17%, which verifies the accuracy of the mechanical model of the rubber damping ring

Bottom-Up Enhancement of g-C 3

Disordered intermolecular interaction carbon nitride precursor prepared by water-assisted grinding of dicyandiamide was used for synthesis of g-C3N4. The final sample possesses much looser structure and provides a broadening optical window for effective light harvesting and charge separation efficiency, which exhibits significantly improved H2 evolution by photocatalytic water splitting. The bottom-up mechanochemistry method opens new vistas towards the potential applications of weak interactions in the photocatalysis field and may also stimulate novel ideas completely different from traditional ones for the design and optimization of photocatalysts

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Application Effect of Integrated Water and Fertilizer Technology for Tomato

Integrated water and fertilizer technology has the advantages of saving water, fertilizer and labour, which is widely applied in tomato plantation. Integrated water and fertilizer technology in topdressing and whole process of big and small tomatoes were studied, and their application effects were contrasted and analyzed, and application advantages and scopes of the two models were concluded

Microscopic Pillars and Tubes Fabricated by Using Fish Dentine as a Molding Template

Biomaterials in nature exhibit delicate structures that are greatly beyond the capability of the current manufacturing techniques. Duplicating these structures and applying them in engineering may help enhance the performance of traditional functional materials and structures. Inspired by gecko’s hierarchical micro- and nano-fibrillar structures for adhesion, in this work we fabricated micro-pillars and tubes by adopting the tubular dentine of black carp fish teeth as molding template. The adhesion performances of the fabricated micro-pillars and tubes were characterized and compared. It was found that the pull-off force of a single pillar was about twice of that of the tube with comparable size. Such unexpected discrepancy in adhesion was analyzed based on the contact mechanics theories

Intestinal necrosis cannot be neglected in a patient with hepatic portal vein gas combined with appendicitis: a rare case report and literature review

Abstract Background Hepatic portal vein gas (HPVG) is a rare acute abdomen, which is not an independent disease. Meanwhile, HPVG combined with appendicitis has been rarely reported. We found only a similar report by looking for literature, but no intestinal necrosis occurred. We report a patient with HPVG, appendicitis and intestinal necrosis was reported in the current study. The patient was given frequent monitoring and had been conducted operation in time. Case presentation An 86-year-old female with appendicitis complicated by HPVG was reported in the present study. Abdominal examination revealed rebound tenderness at the McBurney’s point. Moreover, abdominal computed tomography (CT) revealed gas in portal and mesenteric veins in addition to appendicitis. An emergency operation was planned on the appendix. However, the patient refused surgical treatment. Therefore, conservative treatment of antibiotics and frequent imaging observation was conducted for this patient. Although imaging results suggested disappeared gas in intra- and extra-hepatic portal veins, the small intestine was dilated, after conservative treatment of antibiotics. In addition, signs of diffused peritonitis could also be observed and an exploratory laparotomy was performed. Intra-operative findings had confirmed suppurated appendix, mesenteric ischemia and small intestinal necrosis. Conclusions Frequent monitoring benefits us in observing the progress of intestinal diseases. When there exist other possible causes of HPVG such as infection, it is not easy for us to ignore the possibility of intestinal necrosis

Expired Cefalexin Loaded into Mesoporous Nanosilica for Self-Healing Epoxy Coating on 304 Stainless Steel

A self-healing epoxy coating is creatively prepared by employing expired cefalexin loaded into mesoporous silica nanomaterials (MSNs) for corrosion protection of 304 stainless steel (304SS). A series of physical characterizations, including transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectrometer, and N2 adsorption–desorption isotherms, verified that the cefalexin successfully filled porous MSN. The corrosion resistance of the epoxy (EP) coating incorporated with the cefalexin@MSNs is investigated using a Tafel polarization curve and electrochemical impedance spectra (EIS) in a 3.5 wt.% NaCl solution. It is found that the EP-Cefalexin@MSNs coating has a higher self-corrosion voltage and a lower self-corrosion current density than EP coating. Moreover, the charge transfer resistance (Rct) value of Cefalexin@MSNs coating is twice that of EP coating after immersion for 24 h, indicating that the cefalexin@MSNs significantly enhance the corrosion resistance of the coating under long-duration immersion. The improved corrosion resistance is attributed to the densified adsorption of the cefalexin inhibiting the cathode corrosion reaction, providing a self-healing long-duration corrosion protection for 304SS