Operation Mode Selection Research Articles

Overcoming Half-Duplex Loss in Multi-Relay Networks: Multiple Relay Coded Cooperation for Optimal DMT

This paper studies diversity-multiplexing tradeoff (DMT) of decode-and-forward (DF)-based half-duplex relay networks without a direct path from source to destination. We propose a new multiple relay coded cooperation (MRCC) protocol to overcome the half-duplex loss in DF relay networks and show that the proposed MRCC protocol achieves the MISO/SIMO DMT upper bound as the number of assisting relays increases. The loss of multiplexing gain from the half-duplex constraint is recovered by coded cooperation and successive cancellation. Despite its notable gain in terms of DMT, the proposed MRCC protocol requires only limited feedback information/signaling for relay and operation mode selection. We also derive the achievable DMT of the proposed MRCC protocol when each node has multiple antennas. It is shown that the proposed MRCC protocol achieves K times diversity gain of the point-to-point N × N MIMO case. Compared with existing protocols, the MRCC protocol shows much higher diversity gain for almost all multiplexing gains. Furthermore, our numerical results verify that the proposed MRCC protocol outperforms existing protocols in terms of outage probability for the environments of practical interest.

Study on combustion mode transition of hydrogen fueled dual-mode scramjet engine based on thermodynamic cycle analysis

Hydrogen fueled scramjet is a candidate for use as the engine of the aerospace plane for its high specific impulse. To further improve the engine performance, analysis of combustion mode transition for a hydrogen fueled scramjet engine was investigated in this study. In order to identify the differences between Scram- and Ram-mode cycles in propulsive and economic performances for selection and optimization of operation modes, a thermodynamic cycle analysis was made with a dual-mode scramjet engine. It was found through comparative analysis that the specific impulse of the Ram-mode cycle was superior to that of the Scram-mode cycle in meeting the specific thrust requirement. From the viewpoint of performance optimization, the combustion mode transition in a dual-mode scramjet engine should occur in the range of Mach number 6–7. It was therefore concluded that a dual-mode scramjet engine should be operated as much at the Ram-mode cycle as possible when the flight Mach number is less than 6, and the combustion mode transition between Ram-mode cycle and Scram-mode cycle should take place in the range of flight Mach number 6–7.

Evaluation and improvement of wastewater treatment plant performance using BioWin

In this study, the activated sludge model implemented in the BioWin® software was validated against full-scale wastewater treatment plant data. Only two stoichiometric parameters (Yp/acetic and the heterotrophic yield (YH)) required calibration. The value 0.42 was used for Yp/acetic in this study, while the default value of the BioWin® software is 0.49, making it comparable with the default values of the corresponding parameter (yield of phosphorus release to substrate uptake \((Y_{PO_4 } )\)) used in ASM2, ASM2d, and ASM3P, respectively. Three scenarios were evaluated to improve the performance of the wastewater treatment plant, the possibility of wasting sludge from either the aeration tank or the secondary clarifier, the construction of a new oxidation ditch, and the construction of an equalization tank. The results suggest that construction of a new oxidation ditch or an equalization tank for the wastewater treatment plant is not necessary. However, sludge should be wasted from the aeration tank during wet weather to reduce the solids loading of the clarifiers and avoid effluent violations. Therefore, it is recommended that the design of wastewater treatment plants (WWTPs) should include flexibility to operate the plants in various modes. This is helpful in selection of the appropriate operating mode when necessary, resulting in substantial reductions in operating costs.

FW-DAS: Fast Wireless Data Access Scheme in Mobile Networks

In wireless data access applications, reduction of both the access latency and the wireless traffic volume is essential. In this paper, we propose a fast wireless data access scheme (FW-DAS) for wireless data access applications in which data objects are frequently updated and fast access to data objects is indispensable. In FW-DAS, different operation modes are defined depending on the data object popularity, and only popular data objects are proactively pushed to the access point/base station to minimize the access latency while mitigating the traffic load over the wireless link. An analytical model for the access latency is developed and an operation mode selection algorithm is introduced to reduce the access latency. Extensive simulation results show the effects of access-to-update ratio, data popularity, cache size, data object size, and wireless bandwidth. Analytical and simulation results demonstrate that FW-DAS can reduce the access latency with reasonable traffic load compared with poll-each-read (PER)/callback (CB) and their combinations.

Studies on Construction and Operation Mode of Intelligent Transportation Systems

Government departments of different areas are needed during the construction and operation process of intelligent transportation systems. So there is a contradiction that systems must be integrated but they need to be constructed and operated by different organizations. The division of the construction mission among different organization and the rules that all the joint members have to obey should be clear so that repetition and confliction in the whole system can be avoided. These modes of mission division are compared in this paper to provide a reference for our ITS construction and operation mode selection.

The Choice of 10 kV Neutral Point Operation Mode in Fushun Grid

This paper discusses that the capacitive current is a must of producing arc grounding overvoltage, and the method and necessary to restrain arc grounding over voltage. It also explains the concept of capacitive current and arc suppression coil, and the test method and significance of measuring capacitive current. Based on the comprehensive field test and evaluation of 29 substations, it provides the correct selection of neutral point operation mode and gives a development direction to 10 kV power network neutral point grounding method of Fushun grid.

RF behavior of triple-frequency high power fusion gyrotron

The RF behavior of high power, triple frequency (170-, 127.5-, and 85GHz) gyrotron for fusion application is presented in this paper. The operating mode selection is discussed in detail for each corresponding frequencies and TE34,10, TE25,8 and TE17,5 modes are selected as the operating mode for 170GHz, 127.5GHz and 85GHz operation of the device, respectively. The interaction cavity geometry and beam parameters are finalized by the cold cavity analysis and beam-wave interaction simulations. Considering the beam parameters and the beam launching positions in cavity (beam radius), the design of Magnetically Tunable MIG (MT-MIG) is also presented. Results of MT-MIG confirm the beam launching with desired beam parameters at the beam radius corresponding to the selected operating modes for all three frequencies. The CVD diamond window is also designed for RF power transmission. The beam-wave interaction simulations confirm more than 1MW power at all three frequencies (170-, 127.5-, and 85GHz).

Research on the Design of Transformer Energy-Saving Model

This paper first studied the parameters and power loss of the transformer, then conducted a thorough analysis of differences in technical parameters of transformer, the rate of active power loss and reactive power consumption rate of transformer change as the load. For the characteristics of large load fluctuations, large loss for a long time in the light-load and no-load operation of the distribution transformer, the paper analyzed and introduced in detail the selection of the economic operation mode of distribution transformer, the interval of economic operation, the load regulation and economic load distribution of the transformer.

10kV Grid Arc Grounding Over-Voltage Hazards and Countermeasures

Through the analysis of 2 single-phase grounding over voltage accidents caused by capacitive over current in 10 kV power grid in this paper, the causes and damages of arc grounding over voltage are illustrated, and the necessity of capacitive current test and effective methods are pointed out. The test and assessment to the 29 substations capacitor currents provides a scientific basis for the correct selection of the neutral point operation mode, and the strengths and weaknesses of the neutral Point grounding through the arc suppression circle and the mode trends of 10kV grid neutral grounding are demonstrated.

Research on Construction and Operation Mode of Intelligent Transportation Systems

Intelligent Transportation Systems are highly integrated. Many government and business organizations are needed during the construction and operation process. In this paper, the task of construction and operation for ITS is discussed. Construction and operation mode is divided into government dominant mode, business dominant mode and mixed mode. These modes are compared with construction speed, information-sharing quality, service quality and economic benefits to analyze their applicability. This conclusion provides a reference for our ITS construction and operation mode selection.

Design and validation of a reconfiguration strategy for a redundantly actuated intelligent autonomous vehicle

This paper deals with the reconfiguration of an intelligent autonomous vehicle that utilizes an automatic navigation method and online supervision system and thus can be used to improve the safety, traffic management and space optimization inside the confined space of a port. The bond graph model of the vehicle’s dynamic system is developed in a modular and hierarchical modelling environment. An over-actuated intelligent autonomous vehicle with redundant actuators has four independent driven wheels, four independent braking wheels and a four-wheel steering system. This vehicle can be safely operated with appropriate control law restructuring even when some of its actuators are unusable due to a fault. For actuator fault detection, analytical redundancy relations, which are constraint relations that describe nominal system behaviour and are written in terms of the measured system variables, are derived from the bond graph model. Analytical redundancy relations are continuously evaluated to generate residual signals and the symptoms in these signals are monitored for actuator fault detection and isolation. Once one or more actuator faults are isolated, the system is reconfigured via the selection of an appropriate operating mode to prevent critical or accidental situations. This procedure is validated by considering a fault scenario with two reconfiguration options.

DESIGN AND DEVELOPMENT OF A DUAL OPERATING MODE MICROSTRIP PATCH ANTENNA FOR UNMANNED AERIAL VEHICLE SYNTHETIC APERTURE RADAR

Microstrip patch antenna has been designed and developed for Unmanned Aerial Vehicle based Synthetic Aperture Radar (UAVSAR). This antenna operates in C-Band at the frequency of 5.3GHz with a bandwidth of 80MHz. The radiation patterns of the antenna were specifled to provide a desired scanned area for UAVSAR. The UAVSAR antenna was designed in the form of combination of 3 subpanels to allow dual operating mode (single antenna or dual antenna) selection. Two feed points are provided to the feeding network of each subpanel to reduce undesired power loss. The developed antenna prototype meets the performance requirements of UAVSAR system. It shows promising results in the UAVSAR ∞ight mission conducted in Mersing area, Malaysia for both operating modes.

Performance comparison of combined cooling heating and power system in different operation modes

Operation mode of combined cooling heating and power (CCHP) system determines its energetic and environmental performances. This paper analyzes the energy flows of CCHP system and separated production (SP) system. The fuel energy consumptions of CCHP system following electrical demand management (EDM) and thermal demand management (TDM) are deduced respectively. Three indicators: primary energy saving, exergy efficiency and CO 2 emission reduction, are employed to evaluate the performances of CCHP system for a commercial building in Beijing, China. The feasibility analysis shows that the performance of CCHP system is strictly dependent upon building energy demands. The selection of CCHP operation modes is systemically based on building loads, CCHP system and local SP system. The calculation results conclude that CCHP system in winter under EDM achieves more benefits than in summer. The sensitivity discussion indicates that the coefficient of performance for cooling and the efficiency of electricity generation are the most sensitive variables to the energetic and environmental performances of CCHP system.

A 10 W Diode-Pumped Solid-State Green Laser

This paper reports a 10W solid state green laser TEM00 mode output operation, pumped by 3 x 40W LD arrays. The theoretical analysis of the cavity stability and operation mode selection are presented. To make the system more compact, a Brewster plate is specially designed to function both as a polariser as well as a green output coupler.In the experiment, we obtain maximum 10W green laser TEM00 output at 10kHz by establishing a concave-flat stable resonator. Angle mismatch in the frequency doubling is corrected by optimising the crystal temperature to maximise the laser output. The system is completely enclosed in a customised chassis, enabling further integration of scanner head for application testings as well as inhibiting environmental factors that will affect the performance of the laser.

Proper selection of operation modes for thoracolumbar fractures

胸腰椎骨折发生率约占整个脊柱损伤的90%.其中对不稳定性胸腰椎骨折,无论伴或不伴神经损伤,均可采用手术治疗.但如何选择最佳手术治疗方式较为困难,仍存在诸多争议.笔者在参加一些会议交流及审稿中发现存在手术方式选择欠妥或过度治疗的现象.因此,笔者就如何合理选择胸腰椎骨折的手术方式做一浅析,供骨科同行参考。

Diagnosis and therapy of primary malignant tumors of the heart and pericardium

To summarize and analyze the experience in diagnosis and treatment of primary malignant tumors of the heart and pericardium. The clinical data of 24 patients with malignant tumors of the heart and pericardium treated in our hospital between Jun. 1980 and Mar. 2008 were retrospectively analyzed and the related literature was reviewed. All 24 patients received surgical treatment. Radical resection in 10 cases and partial resection in 6 cases were performed, and the remaining 8 patients received only surgical exploration due to unresectable tumors. One patient died of cardiopulmonary failure in early postoperative stage and all the other patients died within 4 years after operation due to recurrence or metastases. Echocardiography, CT, MRI, 3D-CT, CT of coronary artery and cardiac angiography are helpful for the diagnosis and selection of operation mode. Histological examination is necessary for the final diagnosis. Early diagnosis and surgical resection of the tumor as complete as possible, and combination with post-operative radiotherapy and/or chemotherapy may improve the survival of the patients.

Optimal option of distributed generation technologies for various commercial buildings

With the development of distributed generation (DG) technologies and the implementation of policies to encourage their applications, building combined heat and power (BCHP) is expected to play a greater role in the commercial buildings in the future. BCHP is a promising efficiency improvement and carbon mitigation strategy, but careful selection of technology and operation mode is required to achieve a reasonable system performance according to energy consumption characteristics of buildings and technical features of equipments. This paper analyzed energy consumption characteristics of four typical commercial buildings in Japan and simulated the energy system performances of four mostly widely adopted DG technologies under different operation mode conditions for the four buildings studied. Various scenarios were evaluated and compared regarding energy utilization efficiency, energy saving and environmental effects, as well as economic efficiency. Results show that the hotels and hospitals are more attractive for BCHP because of their stable thermal load demands and a favorable heat-to-power ratio, which is the most compatible match with available DG technologies. Furthermore, some DG technologies are more suitable for a certain type of building than others because of their technical features more matching with the building’s energy consumption characteristics, as well as the user’s motivation of selecting BCHP. In Japan, during selecting DG technologies, the prior order is gas turbines (GT), gas engines (GE), diesel engines (DE) and phosphoric acid fuel cells (PAFC) for the hotels, PAFC, GE and GT, DE for the hospitals, PAFC, DE, GE and GT for the stores, as well as DE, PAFC, GE and GT for the offices.

Surgical treatment of primary malignant tumors of the trachea and main bronchus

To explore the clinical experience of surgical treatment of primary malignant tumors of the trachea and main bronchus. The clinicopathological data of 18 patients with primary malignant tumors of the trachea and main bronchus surgically treated from February 1994 to August 2007 were reviewed retrospectively. The surgical management included sleeve tracheal resection in 8 cases, lower trachea and carina resection with carina reconstruction in 4 cases, local enucleation of the tumor in 4 cases, left or right carino-pneumonectomy and carina reconstruction in 2 cases, and resection of the tracheal or bronchial tumor and reconstruction of the airway under cardiopulmonary bypass in 6 cases. Among the 18 cases, there were 7 adenoid cystic carcinomas, 9 squamous cell carcinomas, 1 lymphoepithelial-like carcinoma and 1 follicular non-Hodgkin lymphoma. All the cases recovered well except one who died of endotracheal bleeding and asphyxia at the 10(th) postoperative day. Surgical resection is the most effective treatment for primary malignant tumors of the trachea and main bronchus. The selection of operation modes should be individualized according to patients' condition. Both complete resection and safety should be taken into consideration simultaneously.

Performance of sea surface salinity and soil moisture retrieval algorithms with different auxiliary datasets in 2-D L-band aperture synthesis interferometric radiometers

The Soil Moisture and Ocean Salinity (SMOS) Earth Explorer Opportunity Mission was selected in May 1999 by the European Space Agency Earth Observation Programme Board to provide global and frequent soil moisture (SM) and sea surface salinity (SSS) maps. SMOS' single payload is the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) sensor, an L-band two-dimensional aperture synthesis interferometric radiometer with multiangular and polarimetric imaging capabilities. The definition of the SMOS Level 2 Processor requires the selection of the optimum operation mode (dual-polarization or full-polarimetric) for each application, the specification of the required auxiliary data, and the optimum retrieval algorithms. Using the SMOS simulator and based on the experience gained in previous works, this paper presents a study of the SM and SSS retrieval capabilities over homogeneous pixels, in the two modes of operation with different auxiliary data. It is found that SSS retrievals using the first Stokes parameter measured in the dual-polarization mode perform somewhat worse than using the vertical (T/sub vv/) and horizontal (T/sub hh/) brightness temperatures measured in the full-polarimetric mode, and the performance degrades for cold waters due to the lower sensitivity of the brightness temperature to SSS at low sea surface temperature (SST). Due to the larger angular variation of T/sub hh/ and T/sub vv/, SM retrievals using T/sub hh/ and T/sub vv/ measured in the full-polarimetric mode exhibit a significant better performance over bare soils than over vegetation-covered soils. Over vegetation-covered soils vegetation parameters (opacity and albedo) can be inferred over a 550-km swath width in the full-polarimetric mode. However, since the first Stokes parameter is independent of both geometric and Faraday rotations, it is very robust in the presence of instrumental and geophysical errors. In the SSS retrieval problem and in the SM retrieval problem (with T/sub hh/ and T/sub vv/ measured in the full-polarimetric mode), the performance of the retrieval algorithms tested is not significantly altered if the model parameters are not exactly known, but are left as adjustable parameters in the optimization process.

The Experience of 196 Cases of Gastric Carcinoma Operation

目的 探讨胃癌淋巴结廓清及手术方式的选择.方法回顾196例经腹胃癌切除患者的临床资料.结果胃癌根治D2或D2+清除155例,其中淋巴结转移105例,姑息切除41例,全胃切除,食管空肠Roux-y吻合95例,胃大部切除101例,联合胰体、尾部、脾切除2例,胃癌根治术后死因中肝转移18例,肺转移8例,骨转移2例,肾衰4例.结论胃体以上近端胃癌行全胃切除D2或D2+清除为标准方式.胃窦癌可行胃大部分切除,但廓清淋巴结需包括1、7、8、9组和第12组,整个清扫面应于大小网膜外。