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Background Thoracic ossification of the posterior longitudinal ligament (T-OPLL) can cause thoracic spinal stenosis, which results in intractable myelopathy and radiculopathy. The etiology of T-OPLL is unknown and the condition is difficult to treat surgically. Whole-genome sequencing identified a genetic variant at rs199772854 of the interleukin 17 receptor C (IL17RC) gene as a potentially pathogenic locus associated with T-OPLL. We aimed to determine whether the rs199772854A site mutation causes abnormal expression of the IL17RC in Han Chinese patients with T-OPLL and predict the possible pathogenic mechanisms of T-OPLL. Analyses were performed to determine whether IL17RC is involved in the pathogenicity of T-OPLL. Methods Peripheral blood and OPLL tissue were collected from a total of 72 patients with T-OPLL disease (36 patients carrying the rs199772854A site mutation in IL17RC and 36 wild-type patients). The expression of IL17RC was analyzed by enzyme-linked immunosorbent assay, reverse transcription-quantitative polymerase chain reaction, immunohistochemistry, and Western blotting. Results rs199772854A mutation resulted in markedly increased IL17RC gene expression levels in peripheral blood samples and the OPLL tissue obtained following clinical surgery (P

Background Disc degeneration (DD) is one of the common diseases worldwide, which deeply influences normal life and leads to excruciating pain. However, an effective treatment for DD is still not identified. Method The present study systemically examined the effect of melatonin on annulus fibrosus (AF) cells of patients with DD. Results Melatonin had the effect of promoting proliferation, inducing autophagy, and suppressing apoptosis on AF cells of patients with DD. Moreover, melatonin contributed to the translation and transcription of autophagy-related protein ATG7 and inhibited the function of miR-106a-5p in AF cells. In addition, the results suggested that miR-106a-5p mediated the expression of ATG7 by directly binding to its 3'UTR in AF cells. Conclusion This research not only gained a deep insight of melatonin mode of action, but also indicated its potential target signaling pathway in AF cells.

As the economy and society enter the period of rapid post-industrialization, the pressures on resources and the environment are becoming more obvious. Therefore, the environmental protection work faces more challenges. There are many important elements in the environmental emergency detection system, such as emergency monitoring data, information, and command transmission. In order to deal with all kinds of sudden environmental pollution accidents in a timely manner and to reduce the damage to the environment caused by accidents, we need to ensure the safety of the environment. Therefore, we must use scientific methods to manage sudden environmental pollution accidents. In this paper, we combine Internet technology, GIS technology and multimedia database technology, and establishes a decision support system for emergency monitoring and disposal based on multimedia information systems. Its basic hardware includes environmental risk source monitoring, emergency monitoring, command and dispatch, environmental emergency network and environmental emergency monitoring center construction. The software system includes basic software environment, environmental emergency monitoring and command information sharing platform, application software and unified portal. The entire system is integrated according to an organized organizational system, providing detection systems and early warning systems for sudden environmental pollution incident prevention and emergency response. The system we designed can collect and process relevant information in a very short time. The system can quickly handle emergency decision-making and minimize the adverse effects caused by sudden environmental pollution accidents. Experiment results show the well performance of the proposed system. The multimedia based user interface guarantees the user experience.

The operation disturbance induced by the solar array drive system (SADS) and the residual vibration of solar array following the attitude adjustment of the spacecraft obviously affect the dynamics environment, quick stabilization, and attitude stability of the high-precision spacecraft. However, these two kinds of vibration disturbance are characterized by distinct vibration categories, direction of vibration, and modal shapes. A multi-degree-of-freedom vibration reduction strategy (VRS) was presented to improve the dynamic characteristics of SADS and then to weaken these disturbances synthetically in this paper. SADS applying this VRS was modeled based on the virtual work principle, and the influence of the stiffness and damping parameters of this VRS on the SADS dynamic characteristics was analyzed. Then a prototype of vibration reduction device (VRD) was designed and verified by disturbance characteristic and modal experiments. The results indicate that the equivalent stiffness of VRD is critical to the natural frequency of SADS and thus should be carefully deliberated to avoid resonance. The equivalent damping of VRD always has positive correlation with modal damping. A good performance up to 40% in terms of operation disturbance suppression and a greater than 56% decrease of the damping time for 99% residual vibration have been obtained.

// Yunlong Ma 1, * , Bin Zhu 2, * , Xiaoguang Liu 1 , Zhongjun Liu 1 , Liang Jiang 1 , Feng Wei 1 , Miao Yu 1 , Fengliang Wu 1 , Hua Zhou 1 , Nanfang Xu 1 , Xiao Liu 1 , Lei Yong 1 , Yongqiang Wang 1 , Peng Wang 1 , Chen Liang 1 and Guanping He 1 1 Department of Orthopedics, Peking University Third Hospital, Beijing 100191, China 2 The Center for Pain Medicine, Peking University Third Hospital, Beijing 100191, China * Authors contributed equally to this work Correspondence to: Xiaoguang Liu, email: xgliudoctor@163.com Keywords: chordoma, iASPP, prognosis, invasion, cisplatin Received: November 30, 2016 Accepted: August 06, 2017 Published: August 11, 2017 ABSTRACT The oncogenetic function of inhibitory member of the apoptosis stimulating protein of p53 family (iASPP) in chordoma is unclear and remains to elucidate. The expression of iASPP in chordoma tissues and cells, its correlation to clinicopathological parameters and the effect on the patients’ prognosis were evaluated. Cellular proliferation, invasion and cisplatin-response were observed after the iASPP knockdown or overexpression in vitro . Co-Immunoprecipitation assay was used to explore the interaction between iASPP and p53. The regulation of miRNA-124 on the expression and apoptotic function of iASPP was explored after transiently transfecting cells with miRNA-124 mimics or inhibitor. Results indicated that iASPP overexpressed in chordoma tissues and cells. Its overexpression was associated with tumor invasion and local recurrence, and was predictive of patients’ poor prognosis. Cells with iASPP-silence showed a decreased ability of proliferation and invasion, but an increasing sensitivity to cisplatin. Besides, iASPP could combine with p53 in either endogenous or exogenous detection. Post-transcriptionally, miRNA-124 negatively regulated the expression of iASPP, which further led to the changes of apoptosis-related proteins. Thus, iASPP overexpression is associated with the clinical outcome in spinal chordoma and influences cellular proliferation, invasion, and the sensitivity to cisplatin.

An equivalent modal analysis method that considers the influence of the drive control is presented for operational spacecraft tracking-drive flexible systems (STFS). The proposed method is verified by simulations and laboratory experiments using a spacecraft model with fixed connections. The effects of the parameters of the drive control, such as the drive speed and control gains of the current loop, on the system’s dynamic characteristics are determined. The results indicate that the drive mechanism with the influence of drive control can be regarded as a torsional spring-dashpot boundary. The drive control causes a decrease in the equivalent stiffness of the drive mechanism but does not affect the equivalent damping. In general, the decrease in the equivalent stiffness is positively correlated with the drive speed and negatively correlated with the control gains. The drive control of the STFS has relatively low influence at low drive speeds but has a significant influence on the system’s dynamic characteristics at high drive speeds. The torsion-mode natural frequencies of the STFS are directly proportional to the control gains and inversely proportional to the drive speed. The relationships between the parameters of the drive control and the torsion-mode modal damping ratios, however, do not conform to a uniform pattern and require further study.

The urban independent coordinate system based on CGCS2000 has a relatively strict conversion correspondence with CGCS2000 coordinate system. Based on the surveying and mapping technical force of class a unit, the conversion of control points can be realized and high precision can be achieved. In the process of topographic map transformation, due to the influence of side length projection deformation, it will have an impact on the area of engineering construction plot. Through the coordinate conversion function of the digital mapping software, the topographic map is transformed to explore the change rate of the converted area and provide decision-making basis for the planning and construction departments.

Implementation of a polyethylenimine ethoxylated (PEIE) interlayer significantly enhances electron injection efficiency from ZnO into light emitting polymers including a blue light emitting polymer with relatively low electron affinity, verified by comparison of current density-voltage characteristics of the electron-only devices with or without a PEIE interlayer. Ultraviolet photoelectron spectroscopy measurements reveal that PEIE forms interfacial dipoles and reduces the work function of ZnO by ca. 1.2 eV, thus facilitating electron injection into light emitting polymers. Neutralized amines rather than protonated amines are responsible for the formation of interfacial dipoles as manifested by N1s core level spectra of the ZnO/PEIE sample. Luminance efficiency of hybrid organic-inorganic light emitting devices employing PEIE interlayer is similar to that of the analogous conventional devices with low work-function metal cathode due to electron injection promoting and hole/exciton-blocking properties of PEIE. Compared to Cs 2 CO 3 , PEIE, which possesses similar surface energy to the organic materials and can form homogeneous film, is expected to collaborate with the adjoining organic layers, without significantly interrupting their morphology, especially for those containing low molecular weight components such as phosphorescent emitters. We envisage that this valuable tribute enables the use of small molecule light emitting materials for device fabrication and is particularly beneficial for the effective introduction of phosphorescent emitters into the emission layer of organic-inorganic light emitting devices. Phosphorescent hybrid organic-inorganic light emitting devices with solution-processed 4,4',4''-tris(carbazol-9-yl)triphenyl-amine (TCTA): 1,3-bis[(4-tert-butylphenyl)-1,3,4-oxadiazolyl]phenylene (OXD-7): Ir-complex emission layer show the maximum luminance efficiency of 64 cd/A and external quantum efficiency of 19.1%, which represent the best efficiency for organic-inorganic light emitting devices reported so far and are approximately 4 times higher than those of the analoguous devices using Cs 2 CO 3 electron injection layer. The luminance efficiency of the devices is rather independent of Ir-complex concentration, indicating balanced hole and electron transport in the emission layer and broad emission zone due to the use of hole-transporting TCTA and electron-transporting OXD-7 as the co-hosts, together with the confinement of the emission zone inside the emission layer and homogeneous dispersion of Ir-compex into the TCTA: OXD-7 host. Furthermore, the efficiency roll-off at high luminance is rather small, for example, the luminance efficiency at 10000 cd/m 2 is 62 cd/A, maintaining 97% of the maximum luminance efficiency. Our findings enrich the organic materials for the preparation of organic-inorganic light emitting devices and pave the way for the future improvement of device efficiency and stability.

Background Ossification of the posterior longitudinal ligament (OPLL) of the spine is a complex, multifactorial disease. Although several genes that are linked to cervical OPLL susceptibility have been reported, specific genetic studies regarding thoracic OPLL are lacking. Whole-genome sequencing has been considered as an efficient strategy to search for disease-causing genes. Methods We analysed whole-genome sequences in a cohort of 25 unrelated patients with thoracic OPLL. Bioinformatics analysis and various algorithms were used to predict deleterious variants. Sanger sequencing was used to confirm the variants. Results Four deleterious mutations in three genes (c.2716C>T (p.Arg906Cys) in collagen type VI α6 (COL6A6); c.1946G>C (p.Gly649Ala) in collagen type IX α1 (COL9A1); and c.301T>C (p.Ser101Pro) and c.171A>G (p.Ile57Met) in toll-like receptor 1 (TLR1)) were successfully identified. All the variants were confirmed by Sanger sequencing. Conclusion The novel deleterious mutations of the three genes may contribute to the development of thoracic OPLL.

Background In our previous whole-genome sequencing study of 30 unrelated northern Chinese Han patients, we identified six single nucleotide polymorphisms (SNPs) in the interleukin 17 receptor C (IL17RC) and collagen type VI α1 chain (COL6A1) genes that were potentially associated with thoracic ossification of the posterior longitudinal ligament (T-OPLL). To determine whether these six SNPs are associated with susceptibility to T-OPLL in the northern Chinese Han population, we performed a case-control association study to confirm specific susceptible loci in the expanded samples. Methods The six SNPs in the IL17RC and COL6A1 genes were analyzed in 200 northern Chinese individuals (100 patients and 100 control subjects) using the Sequenom system. Results The genotype distributions and allele frequencies of each SNP in the control and patient groups were compared. rs201153092, rs13051496, rs199772854, rs76999397, and rs189013166 showed potential pathogenic loci for T-OPLL in the northern Chinese Han population, whereas rs151158105 did not. At the genotype level, the differences in the genotype frequencies of rs201153092, rs13051496, rs199772854, rs76999397, and rs189013166 between T-OPLL cases and controls reached statistical significance. Conclusions To the best of our knowledge, this is the first association study of susceptibility genes in Han Chinese patients with T-OPLL. The results revealed five SNPs in the IL17RC and COL6A1 genes that represented potentially pathogenic mutations in patients with T-OPLL.

Foundation engineering is a comprehensive geotechnical engineering problem, which is costly and time-consuming. And the construction quality is difficult to observe and determine, so is the strengthening and repairing work later. Therefore, people attach greater importance to the selection before building the foundation. This paper, based on the statistical analysis of the forms, characteristics and applicable scopes of the building foundation, establishes the hierarchical factor system and introduces the theory of fuzzy system in order to improve the traditional AHP method and to propose a more comprehensive fuzzy evaluation system combining more accurate FAHP method and interval theory together. Additionally, the basic principles and algorithm of artificial neural network are analyzed and expounded, then combine neural network and fuzzy system to build a fuzzy neural network system for architectural foundation selection. Furthermore, simulated testing and performance analysis for the two models are conducted so as to offer some guidance for the project selection.

This paper analyses connections between the input and output in different economic departments. Based on the input-output theory, the relationship among consumption, investment, export data and electricity consumption is studied. Firstly, mathematical model of “Troika” leading to electricity consumption is built. Secondly, by utilizing input-output tables in 2002, 2007 and 2012 published by Statistics Bureau of Fujian and industrial electricity consumption tables in Fujian Province published by State Grid Fujian Electric Power Company, relationship and developing trends between electricity consumption and “Troika” are calculated. Study results show that pushing effect of investment to electricity consumption increases year by year, while that of consumption decreases. The pushing effect of export is the smallest. From industrial views, the electricity consumption caused by other manufacturing industry accounts for the biggest proportion, while that caused by finance represents the smallest percentage.

Compared with the AC distribution network, the DC distribution network has the advantages of lower line losses, better power quality, higher reliability and being suitable for all kinds distributed generation and DC load access, etc. This paper firstly studies the models of PV and energy storage connected to the DC distribution network. Then, a new type of DC distribution network topology with hybrid DC circuit breaker is proposed. A coordinated control strategy is also proposed, which can control energy storage to improve the stability of the system. Finally, using PSCAD/EMTDC to model and simulate. The simulation results show that the proposed topology of DC distribution network and control strategy can quickly remove the fault, shorten the fault power failure time and ensure the safe and stable operation of the system, which greatly improves the operation efficiency and safety level of the power grid.

Objective The majority of genes are alternatively spliced and growing evidence suggests that alternative splicing is modified in cancer and is associated with cancer progression. Systematic analysis of alternative splicing signature in ovarian cancer is lacking and greatly needed. Methods We profiled genome-wide alternative splicing events in 408 ovarian serous cystadenocarcinoma (OV) patients in TCGA. Seven types of alternative splicing events were curated and prognostic analyses were performed with predictive models and splicing network built for OV patients. Results Among 48,049 mRNA splicing events in 10,582 genes, we detected 2,611 alternative splicing events in 2,036 genes which were significant associated with overall survival of OV patients. Exon skip events were the most powerful prognostic factors among the seven types. The area under the curve of the receiver-operator characteristic curve for prognostic predictor, which was built with top significant alternative splicing events, was 0.937 at 2,000 days of overall survival, indicating powerful efficiency in distinguishing patient outcome. Interestingly, splicing correlation network suggested obvious trends in the role of splicing factors in OV. Conclusions In summary, we built powerful prognostic predictors for OV patients and uncovered interesting splicing networks which could be underlying mechanisms.

This paper describes the On-Board Data Handling Subsystem of remote sensing satellite, which plays nowadays a relevant role to support satellite assembling, integration and testing activities in the implementing complex system-level requirements. Firstly, the architecture and functionalities of On-Board Data Handling Subsystem are described. Secondly, layered On-Board Data Handling Subsystem flight software architecture based on onboard route as well as software maintenance and tolerance designs are depicted. In particular, we present the redundancies and fault processing means for ensuring the correctness of On-Board Data Handling Subsystem.

Due to the high frequent drowning accident, a new type of drowning-preventing device established on the base ofBeiDou Navigation Satellite System, using the compatibility of GPS tech, GSM, GPRS and other Internet of Things technology as well as Vital Signs Detection technology is designed. The situation whether a person is in drowning is judged by the device monitoring the heart rate and oxygen saturation. And the device utilizes Global Positioning System module to find exact location and uses GPRS to send the information of life signal and position. Based on the experiment, this system can decrease the rate of the drowning accident tosome extent.

Nozzle guide vanes (NGV) of gas turbine engines are the first components to withstand the impingement of hot combustion gas, and therefore often suffer thermal fatigue failures in service. A lifing analysis is performed for the NGV of a gas turbine engine using the integrated creep-fatigue theory (ICFT). With the constitutive formulation of inelastic strain in terms of mechanism-strain components such as rate-independent plasticity, dislocation glide-plus-climb, and grain boundary sliding, the dominant deformation mechanisms at the critical locations are thus identified quantitatively with the corresponding mechanism-strain component. The material selection scenarios are discussed with regards to damage accumulated during take-off and cruise. The interplay of those deformation mechanisms in the failure process are elucidated such that an “optimum” material selection solution may be achieved., ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition, June 13-17, 2016, Seoul, South Korea, Series: ASME Proceedings

NPP’s power supply system is repairable and there is common cause failure between the components. The repair rate is introduced and total signaling is considered in the improved GO-FLOW method, aimed at reliability analysis for NPP’s power supply system. Traditional GO-FLOW operators’ algorithms are improved. Comprehensively considering the effect of total signaling flow in the power supply system, the equivalent reliability parameter model and common cause failure probability model of multimodal repairable components are constructed. The improved GO-FLOW model of NPP’s power supply system is set up. Based on the proposed model, components’ reliability parameters are computed. The failure probability time-varying trend in thirty years, respectively, of NPP’s offsite power source and power supply system, is simulated and analyzed. Compared with calculation results of dynamic fault tree analysis method, the validity and the simplicity of the improved GO-FLOW method are verified. The effectiveness and applicability of the improved GO-FLOW model for NPP’s power supply system are proved by simulation examples.

The load transferring mechanism was investigated and then used to establish the load transferring equation. A calculation method for the vertical load transferring characteristic of the rock socketed pile was proposed to make up for the deficiency of that method in current norms. This method can derive not only the expression of the socketed length of pile, but also the load sharing ratio at the pile tip. Case histories were used to observe the variation of the socketed length and the load sharing ratio at the pile tip over the settlement at the pile top. The results indicate that the required socketed length increases as the settlement requirement at the pile top decreases. The larger the settlement at the pile top, the higher the load sharing ratio at the pile tip. The increment of the socketed length ratio results in the descent of the bearing ratio of the pile tip resistance when other conditions remain unchanged. The method can determine the socketed length of the pile both safely and economi...

Large eddy simulation (LES) is recognized as a promising method for numerical simulation in combustion systems. A LES attempt in a model combustor has been made, and a few important issues including grid size, inflow condition, wall boundary conditions, physical sub-models and data sampling, have been carefully considered. It is found that the turbulence forcing with the vortex method at the air/fuel inlets does not affect the LES results for the present configuration and the turbulence can develop naturally in the inlet section. Moreover, significant computing power is required for LES to capture both the high and low frequencies of interest in a turbulent reacting flow. In the paper, some of the numerical results are presented and compared with a comprehensive experimental database, which indicates that LES can provide reasonable predictions for the mean axial velocity and temperature distributions inside the combustion chamber. However, in order to make LES a valuable and cost-effective tool in the development of advanced combustion systems, some fundamental questions remain to be addressed and more validation efforts are required.Copyright © 2010 by Her Majesty the Queen in Right of Canada

Flood control resources are valuable resources for flood control and rescue, providing the flood relief work with the most direct rescue workers, tools as well as equipment. With the continuous development of society and economy, local governments at all levels, especially those of which are seriously affected by flood and waterlogging, have raised higher requirements for the allocation of flood control resources. When disasters such as flood and waterlogging happen, a reasonable allocation of flood control resources can quickly deploy relevant flood control resources for the disaster relief work and play an important role in reducing damage to personnel and property loss to a minimum, which stabilizes and promotes the socioeconomic development. Research of resource allocation of flood control based on GIS (Geographic Information System) is gradually becoming an important technical support for scientific resource allocation. This research focuses on the introduction of the characteristics and advantages of the heat map system based on GIS and its application in resource allocation of flood control. The important role the heat map system based on GIS plays in allocation and management of flood control resources is introduced in the applying case of Guangzhou.

To satisfy the growing of land demand from economic development, a large scale of land reclamation from sea has been carried out in Inner Lingdingyang Bay in the Zhujiang (Pearl) River estuary in recent years. As a result, the tidal flat and the water channels became narrow, the frequency of floods increased, and the environment was undermined. Guangzhou Marine Geological Survey (GMGS) conducted an integrated project for marine geo-environment and geo-hazards survey in 2003. With the integration of multi-temporal remote sensing images of 1977, 1978, 1988, 1996, and 2003, GIS spatial analyzing approach and GPS technique, as well as field data and other background data of the region, this research investigated the comprehensive characteristics and the drivers of coastal land use dynamics and shoreline changes in Inner Lingdingyang Bay. The results reveal that the reclaimed coastal land was mainly for agriculture and aquaculture in early years, but now they are used for construction sites of harbors and industries, especially high-tech industry.

Computational Fluid Dynamics (CFD) is increasingly being applied to model turbulent jet flows in practical applications ranging from gas turbine combustion to noise control and thrust augmentation....

Significant error caused by plasticity at the hole edge may arise when measuring sufficiently high welding residual stress by means of the hole drilling method. According to elastoplastic theory, a critical parameter of plastic deformation round the centre hole is obtained. On the basis of this critical parameter, a simple method is proposed to correct the stresses for the plasticity effect. It is shown in the experiments with welded joints that the correction method may improve the accuracy of high residual stress measurement.

Within a net centric environment, military communication networks (MCNs) are mostly characterized by heterogeneous nodes and multilinked relationships between nodes. Traditional graph theory based network structure models are difficult to describe such characteristics of MCN accurately. In order to analyze, design, and build MCNs for a net centric environment, we propose a novel structure model based on super network by extending and integrating Jeff Cares' combat network model and Hans E.keus' Net force Reference Model. The model's mathematical structure is given in detail. The proposed model is able to represent two key characteristics of MCNs, i.e. node's functional types and link's transmission types. Based on the proposed model, the military communication super network can be decomposed into several functional or special sub-networks which are more meaningful in the military background. As an example, a joint operational forces communication super network structure is given to validate the proposed super network model.

The 40th AIAA Aerospace Sciences Meeting and Exhibit Jan. 14-17/02, Reno NV, available, unclassified, unlimited

The 6th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows. April 6-11, 2003., Shanghai, China, available, unclassified, unlimited

available, unclassified, unlimited

One of the main reasons of lag in braking control technology of hoist exchange drag is that braking torque is not adjustable. And the braking torque of speed closed-loop of fuzzy neural network controller (NNSOC) can not only ensure that deceleration in braking is constant, but also it can be regulated in the wider framework. The coil current of nozzle flapper valve of pressure closed-loop of NNSOC changes with the change of braking torque. Mze–I characteristic curve of the valve was simulated to obtain the braking torque expectation (Mze). NNSOC adopted 3-layer structure of BP network, and network input / output samples were based on fuzzy rules and collected by simulation test. After doing repeated experiments, the experimental results show that that traingdx learning function and the best network structure can adjust network weights to memory and update the rules of NNSOC. The network testing results show that the response characteristics of NNSOC (braking torque and its overshoot of control current, network response time) can ensure that the braking deceleration is constant and the braking is smooth, safety, utility, energy-saving.

This paper presents a study of temperature rise in the exhaust system of a combustor test rig, Test Cell #1, at the Gas Turbine Laboratory, Institute for Aerospace Research, the National Research Council of Canada. As the flow regime is supersonic with a mixture of hot air & water vapour, condensation of water vapour in the system is suggested to explain the temperature rise observed along the exhaust pipe. The method of Computational Flow Dynamics is used to carry out the first investigation on this hypothesis. The exhaust system is reproduced by CAD, meshed and modelled by the ANSYS-FLUENT CFD package. Simulations of a two-phase complex mixture are performed. The numerical results indicate that the pressure control devices in the exhaust flow towards the stack create phenomena similar to nozzles and yield condensed water into the system. The simulations of liquid phase content and temperature fields are qualitatively consistent with experimental observations and support the hypothesis that condensation is occurring and may therefore threaten the structural integrity of the system through thermal effects., ASME Turbo Expo 2009: Power for Land, Sea, and Air, June 8–12, 2009, Orlando, FL USA

The combustor and turbine of a gas turbine engine are directly connected, and their flow fields and performance are closely coupled. However, to reduce turn-around time and avoid numerical difficulties in the development of gas turbine engines, numerical simulations of gas turbine combustors are usually performed without turbine components attached. This decoupling approach is investigated numerically in this paper. A micro gas turbine combustor is used as a test model, and the two-phase, turbulent, reacting flow fields of the combustor with and without nozzle guide vanes (NGV) have been simulated. Complex flow phenomena such as cross-jet flows, separations, recirculation zones, conjugate heat transfers, fuel droplet heating, vaporizing and combusting etc. are observed. The flow features of axial and tangential velocities, Mach number, and static pressure at the combustor exit are substantially different between these two cases. The effect of NGV on the combustor flow field decreases as the distance away from the NGV leading edge increases. At the cross-section, one span upstream of the NGV leading edge, the distributions of flow parameters with and without NGV are almost the same. The findings suggest that for the present combustor configuration, simulations of the combustor and turbine components could be decoupled if the interfacing cross-section or combustor exit is located at one span upstream of NGV. The present study is still preliminary and the results could be configuration dependent. Further study on the combustor-turbine decoupling issue for a traditional gas turbine combustor is on the way., ASME Turbo Expo 2009: Power for Land, Sea, and Air, June 8–12, 2009, Orlando, Florida, USA

The relationship between AlGaN/GaN HEMT gate field plate (FP) and surface-state-related gate lag phenomena is investigated by two-dimensional numerical transient simulations to study the mechanism of the influence of FPs on current collapse. The simulations reveal that adding a field plate has a noticeable impact on the extent of current collapse while it has no influence on lapsed time. The FP is found to suppress current collapse through reducing the ionization probability of surface states by enhancing free hole accumulation next to the AlGaN surface between gate and drain.

We report efficient phosphorescent hybrid organic-inorganic light emitting devices using poly(ethylenimine) as electron-injection layer and interfacial modifier for metal oxides and solution-processed small molecule emissive layers. As a first step, the hole transport layers with various HOMO levels and the hole mobility values including TAPC, TCTA and mCP are evaluated. The results indicate that devices using a TAPC layer show the best luminance and power efficiencies. Subsequently, the optimum phosphor concentration is determined to be ca. 5%. Enlarged efficiency roll-off with increasing current density is observed in devices using the phosphor concentration above the optimum value. We also investigate the morphologies of films having different phosphor concentrations on the top of bare or PEIE-covered glass substrates, which is closely related to device performance. All the films have the RMS values of ca. 1 nm, indicating high-quality solution processed small molecule films. The blue, yellow and red devices show the maximum external quantum efficiencies of 17.3%, 10.7% and 7.3%, respectively. These efficiencies are 17.0%, 10.6% and 5.8% at 1000 cd·m-2, only showing a small roll-off, which can be attributed to alleviated triplet-triplet and triplet-polaron interactions in a broad carrier recombination zone due to using the mixed hole-transport and electron-transport materials as the co-hosts. In addition, these devices exhibit the respective Commission International Eclairage (CIE) coordinates of (0.16, 0.36), (0.50, 0.49) and (0.66, 0.32), which almost traverse the whole visible light region. Furthermore, the hybrid two-colored white devices show a luminance efficiency of 31 cd·A-1, power efficiency of 14.8 lm·W-1 at 1000 cd·m-2 and the operating current-insensitive CIE coordinates of (0.32, 0.42). The efficiencies represent the significant improvement over the previously reported values, which can be attributed to high-quality small molecule films on PEIE, and in particular to the unique properties of small molecule host materials such as balanced carrier transport and high triplet energy. Further efforts including selection of high-mobility electron transport host material and phosphors with high luminescence quantum yield are made to increase the efficiency and reliability of hybrid organic-inorganic light emitting device.

Accurate aircraft engine fault detection and diagnosis is vitally important reducing operating costs and improving safety. Various data and knowledge could be collected from manufacture, test bed measurement systems, on-board measurement systems, maintenance history and experts' experience. Integrating and fusing these data and information to provide intelligent fault diagnosis and maintenance schedules are essentially to both civil and military engines. Information fusion strategies and architectures have been developed over the last several years for improving upon the accuracy, robustness and overall effectiveness of diagnostic and prognostic technologies. Fusion of relevant sensor data, maintenance database information, and various diagnostic and prognostic technologies has been proven effective in reducing false alarm rates, increasing confidence levels in early fault detection, and predicting time to failure or degraded condition requiring maintenance action. In this paper, we researched on the architectures of fusion systems. A four-level model was presented to fit the usage in aircraft engines fault detection and diagnosis. To generate the deviations for gas path fault detection, baseline values should be chosen firstly. We analyzed choosing baseline values and generating deviations in detail. Then, the fuzzy set was introduced to descript the degree of symptoms belonging to fault patterns. A method based on fuzzy set to isolate fault and quantify the deterioration of performance of components was presented. We also demonstrated the method with an example. For this method, it is not necessary to have more measurements than fault patterns. The fault diagnosis system based on it is very easy to construct and extend too

The flow field of a propane-air diffusion flame combustor with interior and exterior conjugate heat transfers was numerically investigated. Solutions obtained from four turbulence models together with a laminar flamelet combustion model, discrete ordinates radiation model and enhanced wall treatment are presented and discussed. The numerical results are compared, in detail, with a comprehensive database obtained from a series of experimental measurements. It is found that the Reynolds stress model (RSM), a second moment closure, illustrates superior performance over three popular two-equation eddy-viscosity models. Although the main flow features are captured by all four turbulence models, only the RSM is able to successfully predict the lengths of both recirculation zones and the turbulence kinetic energy distribution in the combustor chamber. In addition, it provides fairly good predictions for all Reynolds stress components, except for the circumferential normal stress at downstream sections. However, the superiority of the RSM is not so obvious for the temperature and species predictions in comparison with eddy-viscosity models, except for the standard k-e model. This suggests that coupling between the RSM and combustion models needs to be further improved in order to enhance its applications in practical combustion systems.Copyright © 2005 by ASME

The practical design of GaN-based Schottky barrier diodes (SBDs) incorporating a field plate (FP) structure necessitates an understanding of their working mechanism and optimization criteria. In this work, the influences of the parameters of FPs upon breakdown of the diode are investigated in detail and the design rules of FP structures for GaN-based SBDs are presented for a wide scale of material and device parameters. By comparing three representative dielectric materials (SiO2, Si3N4 and Al2O3) selected for fabricating FPs, it is found that the product of dielectric permittivity and critical field strength of a dielectric material could be used as an index to predict its potential performance for FP applications.

An intermittent connection is one of the major problems that affect the network reliability and communication quality.However,little attention has been paid to the detection,analysis and localization of the intermittent connections.Partially due to the limitations of the DeviceNet protocol,there is no effective online diagnostic tool available to identify the location of intermittent connection.On the basis of different DeviceNet fault scenarios induced by intermittent connections,a new graph-based diagnostic method is developed to analyze DeviceNet fault patterns,identify the corresponding fault scenarios,and infer the location of the intermittent connection problem by using passively captured network faults.A novel error source analysis tool,which integrates network data-link layer analysis and feature based network physical layer information,is developed to restore the snapshots of the network communication at each intermittent connection induced error.A graph based location identification method is developed to infer the location of the intermittent connections based on the restored error patterns.A 3-node laboratory test-bed,using master-slave polling communication method,is constructed to emulate the intermittent connection induced faults on the network drop cable by using digital switches,whose on/off states are controlled by a computer.During experiments,the network fault diagnosis is conducted by using information collected on trunk cable(backbone).Experimental study shows that the proposed method is effective to restore the snapshots of the network errors and locate the drop cable that experiences the intermittent connection problem.

To ensure insulation system reliability of rotating machines driven by power electronics, accelerated tests under repetitive impulsive voltages should be performed on turn-to-turn insulation according to the standards provided by the International Electrotechnical Commission. The parameters of repetitive impulsive voltage can significantly influence insulation lifetime, and thus, voltage parameters should be carefully controlled during the accelerated tests. To increase endurance test efficiency when testing many insulation specimens in parallel, the rise time of impulsive voltage should be controlled at certain constant values after the breakdown of one or more specimens to obtain objective endurance test results. This study provides a description of a novel square wave voltage generator used for the insulation evaluation of rotating machines driven by power electronics. A single-channel generator with variable rise times used for one specimen and a multi-channel generator with a constant rise time used to test five specimens in parallel are presented based on a push-pull solid-state switch. In the multi-channel generator, the RC parameter of the high-voltage circuit can be adjusted automatically by resorting to controlling units and a circuit structure after the breakdown of one or more samples when performing endurance tests on parallel specimens to keep the rise time of impulsive voltage at constant values. The multi-channel generator can significantly increase the endurance evaluation efficiency of the insulation systems of rotating machines fed by power electronics.

Postprandial hypotension (PPH) occurs frequently in the elderly; the magnitude of the fall in blood pressure (BP) is related to the rate of glucose entry into the duodenum during intraduodenal glucose infusion and spontaneous gastric emptying (GE). It is unclear if glucose concentration affects the hypotensive response. Gastric distension may attenuate PPH; therefore, meal volume could influence the BP response. We aimed to determine the effects of 1) drink volume, 2) glucose concentration, and 3) glucose content on the BP and heart rate (HR) responses to oral glucose. Ten subjects (73.9 ± 1.2 yr) had measurements of BP, GE, and blood glucose on 4 days after 1) 25 g glucose in 200 ml (12.5%), 2) 75 g glucose in 200 ml (37.5%), 3) 25 g glucose in 600 ml (4%), and 4) 75 g glucose in 600 ml (12.5%). GE, BP, HR, and blood glucose were measured for 180 min. After all drinks, duodenal glucose loads were similar in the first 60 min. Regardless of concentration, 600-ml (but not 200-ml) drinks initially increased BP, and in the first 30 min, systolic BP correlated ( P < 0.01) with volume in both the proximal and total stomach. At the same concentration (12.5%), systolic BP fell more ( P = 0.02) at the smaller volume; at the same volumes, there were no effects of concentration on BP. There was no difference in the glycemic response to drinks of identical glucose content. We conclude that 1) ingestion of glucose at a higher volume attenuates and 2) under constant duodenal load, glucose concentration (4–37%) does not affect the fall in BP.

The aims of this study were to evaluate (i) the relationship between transpyloric flow (TF) assessed by Doppler ultrasonography and scintigraphy, (ii) the effects of healthy aging on TF and gastric emptying (GE), and (iii) the relationship between the glycemic response to oral glucose and TF. Ten healthy “young” (7 M, 3 F) and 8 “older” (4 M, 4 F), subjects had simultaneous measurements of TF, GE, and blood glucose after a 600-ml drink (75 g glucose labeled with 20 MBq 99mTc-sulfur colloid) while seated. TF measured by ultrasound was measured during drink ingestion and for 30 min thereafter. GE was measured scintigraphically for 180 min after drink ingestion. Blood glucose was measured before the drink and at regular intervals until 180 min. During drink ingestion, TF was greater (P < 0.05) and GE faster (retention at 60 min: 70.8 ± 3.3 vs. 83.8 ± 4.6%; P < 0.05) in young compared to older subjects. There was no difference in fasting blood glucose between the two groups but the magnitude of the rise in blood glucose was greater in the young compared to the older subjects; (at 15 min 2.4 ± 0.3 vs. 1.5 ± 0.5 mmol/L; P < 0.05). In contrast, after 90 min blood glucose concentrations were higher in the older subjects. There were significant relationships between the early blood glucose concentration and both TF (e.g., at 15 min: r = 0.56, P < 0.05) and GE (e.g., at 15 min: r = −0.51, P < 0.05). In conclusion, the results of this study indicate that (i) TF is initially less, and GE slower, in older compared to young subjects; (ii) the initial glycemic response to oral glucose is related to TF; and (iii) measurements of TF by ultrasound and scintigraphy correlate significantly.