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Abstract: Since the thermophysical properties of water change dramatically at near-critical and pseudocritical point, the instability of natural circulation at supercritical pressure may occur in a loop. To predict the region of instability of natural circulation at supercritical pressure, a test loop was built at Tsinghua University. The paper presents the information of the test loop and a numerical analysis model for the loop. The paper verified the numerical analysis code by experiment results and using the code to analyze the instability of the loop. The paper concludes conclusion that there will be no Ledinegg instability occurring at supercritical pressure in the loop. [Copyright &y& Elsevier]

Abstract: In the case of the scientometric evaluation of multi- or interdisciplinary units one risks to compare apples with oranges: each paper has to be assessed in comparison to an appropriate reference set. We suggest that the set of citing papers can be considered as the relevant representation of the field of impact. In order to normalize for differences in citation behavior among fields, citations can be fractionally counted proportionately to the length of the reference lists in the citing papers. This new method enables us to compare among units with different disciplinary affiliations at the paper level and also to assess the statistical significance of differences among sets. Twenty-seven departments of the Tsinghua University in Beijing are thus compared. Among them, the Department of Chinese Language and Linguistics is upgraded from the 19th to the second position in the ranking. The overall impact of 19 of the 27 departments is not significantly different at the 5% level when thus normalized for different citation potentials. [Copyright &y& Elsevier]

Abstract: Hydraulic Control Rod Drive Technology (HCRDT) is a newly invented patent of the Institute of Nuclear and New Energy Technology of Tsinghua University which owns HCRDT’s independent intellectual property rights while the integrated valve made up of three direct action solenoid valves is the key part of this technology. Therefore, the performance of the solenoid valve affects the integrated valve and the HCRDT directly. In this paper, firstly, we improve particle swarm optimization (PSO) by Cloud Model and the improved PSO is called CloudPSO. Then, the method is used to optimize the parameters of the direct action solenoid valve. At last, the results are verified by the experiments. The results prove that the method is feasible and accurate to obtain the key parameters of the solenoid valve in order to achieve the biggest electromagnetic force. Besides, the algorithm is analyzed. [Copyright &y& Elsevier]

Abstract: The Compact Pulsed Hadron Source (CPHS) at Tsinghua University will produce neutrons by bombarding a 13-MeV proton beam from a LINAC system on a beryllium target. One of the purposes of this neutron source is to provide the neutron facilities for characterization of advanced materials with an emphasis on soft matter and biological systems, for which high cold-neutron fluxes are essential. The design and optimization of the solid-methane moderator system aim at the enhancement of cold neutron production. This paper describes the moderator configuration, the associated gas-handling and cryogenic apparatus, and the operation procedure. [Copyright &y& Elsevier]

Abstract: The Compact Pulsed Hadron Source (CPHS) system has been proposed and designed by the Department of Engineering Physics of Tsinghua University in Beijing, China. It consists of an accelerator front-end—a highintensity ion source, a 3 MeV radiofrequency quadrupole linac (RFQ), and a 13 MeV drift-tube linac (DTL), a neutron target station, and some experimental stations. In design of our RF power supply, both RFQ and DTL share a single klystron which is capable of 2.5 MW peak RF power and a 3.33% duty factor. The 325MHz klystron contains a modulating anode and has a 100kW average output power. Portions of the RF power system, such as pulsed high voltage power supply, modulator, crowbar protection and RF power transmission are all presented in details in this paper. [Copyright &y& Elsevier]

Abstract: A cold neutron radiography/tomography instrument was designed and will soon undergo construction at the Compact Pulsed Hadron Source (CPHS) of Tsinghua University, China. In this paper, we report the physical design of the instrument and propose a scheme to implement several techniques at a later phase to enhance the utilization of the flux on larger samples. This includes code-aperture, grating-based imaging, prompt gamma-ray analysis and 3D emission CT. [Copyright &y& Elsevier]

Abstract: Gas-to-liquids (GTL) as an alternative to diesel is considered to be one of the technical options to reduce petroleum consumption in the on-road transportation sector. Between May and August 2007, a joint demonstration program by Tsinghua University, Beijing Transit, Cummins Corporation and Shell Corporation was carried out in Beijing. The program focused on the supply systems and vehicle use of GTL fuel. The demonstration fleet was formed by four transit buses fueled with GTL and four with diesel. It was demonstrated that GTL has good compatibility with diesel in terms of fuel supply system and vehicle use. This paper compares the energy consumption and GHG emissions of diesel and GTL fuel supply chains by life cycle analysis based on demonstration results. The results indicate GTL’s large range (reported 54–70%) in synthesis efficiency, as the key factor in determining energy consumption and GHG emissions within the GTL fuel supply chain. For the probable case (GTL synthesis efficiency: 65%), the life cycle energy consumption and GHG emissions of GTL fuel are 42.5% and 12.6% higher than that of diesel. For two sensitivity analysis cases (GTL synthesis efficiency: 54% and70%), energy consumptions are 74.2% and 31.2% higher and GHG emissions are 27.3% and 7.4% higher than that of the diesel fuel supply chain. If the efficiency of the GTL synthesis process is improved to 75%, then the GHG emissions level of the GTL fuel supply chain can be reduced to the same level as the diesel fuel supply chain. [Copyright &y& Elsevier]

Abstract: Control Rod Hydraulic Drive Mechanism (CRHDM) is a newly invented patent of the Institute of Nuclear and New Energy Technology Tsinghua University which owns CRHDM''s independent intellectual property rights while the integrated valve made up of three direct action solenoid valves is the key part of this mechanism. Therefore, the performance of the solenoid valve affects the integrated valve and the CRHDM directly. In this paper, we present a method to design the parameters of the direct action solenoid valve based on orthogonal experiment design, back propagation (BP) neural network and particle swarm optimization (PSO). The result proves that the method is feasible and accurate to design the parameters in order to obtain the biggest electromagnetic force. Besides, the result also shows that it is the current which influences the electromagnetic force of the direct action solenoid valve most. [Copyright &y& Elsevier]

Abstract: The paper highlights the energy dilemma in China’s modernization process. It explores the technological and policy options for the transition to a sustainable energy system in China with Tsinghua University’s Low Carbon Energy Model (LCEM). China has already taken intensive efforts to promote research, development, demonstration and commercialization of sustainable energy technologies over the past five year. The policy actions cover binding energy conservation and environmental pollution control targets, economic incentives for sustainable energy, and public R&D supports. In order to achieve the sustainable energy system transformation eventually, however, China needs to take further actions such as strengthening R&D of radically innovative sustainable energy technologies and systems such as poly-generation, enhancing the domestic manufacturing capacity of sustainable energy technologies and systems, creating stronger economic incentives for research, development, demonstration and commercialization of sustainable energy technologies, and playing a leading role in international technology collaborations. [ABSTRACT FROM AUTHOR]

Abstract: Pressurized and Depressurized Loss Of Forced Cooling (PLOFC and DLOFC) are two important design basis accidents for high temperature gas-cooled reactors. Analysis of the reactor characteristic behaviors during LOFC can provide useful reference to the physics, thermohydraulic and structure designs of the reactor core, and can also verify the design of the Residual Heat Removal System (RHRS). The 200MWe High Temperature gas-cooled Reactor Pebble-bed Module project (HTR-PM), designed by the Institute of Nuclear and New Energy Technology (INET) of Tsinghua University in China, is characterized by its inherent safety features, such as shutdown ability via negative temperature coefficients of reactivity, passive mechanism of decay heat removal and so on. In this paper, two cases of loss of forced cooling accidents have been analyzed by using THERMIX code based on the preliminary design of the HTR-PM. With respect to the DLOFC, the effects of related key parameters on the maximum temperatures of fuel element and the reactor pressure vessel (RPV), as well as the decay heat removal by the RHRS are studied in detail. From the calculation results, it is shown that, in the LOFC accidents, the maximum temperatures of the fuel element and the RPV are below the safety limits and the RHRS can effectively remove the decay heat from the core, so as to keep the reactor in a safe state. As compared with the PLOFC accident, the DLOFC accident will lead to a much higher fuel element temperature but lower RPV temperatures and RHRS heat load. The analyses also illustrate that the decay heat level, the emissivity of RPV and water-cooling panel, and the average temperature of the water-cooling panel, play important roles in the DLOFC accident. [Copyright &y& Elsevier]

Abstract: An elasto-plastic model originally developed at Tsinghua University (Tsinghua elasto-plastic model) for soils reflects the observed non-linearity and dilatancy of soils in laboratory tests. The model incorporates a yield criterion, an associated flow rule and a work-hardening law, which can be determined by laboratory tests. This paper presents a modified Tsinghua elasto-plastic constitutive model, which incorporates a function of plastic work as the hardening parameter in the original Tsinghua elasto-plastic model. The modified model has 12 parameters, which are easily determined using conventional triaxial shearing and isotropic compression tests. It can be used to describe strain hardening followed by strain-softening behaviour and to simulate dilatancy during shear application. The modified model was used to determine the relationship between load and settlement for a shallow footing founded on dense Yongding River sand. The results of the numerical analyses were in agreement with the results of hydraulic gradient laboratory tests. The results showed in a preliminary way that the modified model developed in this study was effective for simulating the strain-softening boundary-value problems common in geotechnical engineering. [Copyright &y& Elsevier]

Abstract: Nuclear technology applications have been very important research fields in Tsinghua University (THU) for more than 50 years. This paper describes two major directions and related projects running in THU concerning nuclear technology applications for radiation imaging and nuclear technology applications for astrophysics. Radiation imaging is a significant application of nuclear technology for all kinds of real world needs including security inspections, anti-smuggling operations, and medicine. The current improved imaging systems give much higher quality radiation images. THU has produced accelerating tubes for both industrial and medical accelerators with energy levels ranging from . Detectors have been produced for medical and industrial imaging as well as for high energy physics experiments such as the MRPC with fast time and position resolutions. DR and CT systems for radiation imaging systems have been continuously improved with new system designs and improved algorithms for image reconstruction and processing. Two important new key initiatives are the dual-energy radiography and dual-energy CT systems. Dual-energy CT imaging improves material discrimination by providing both the electron density and the atomic number distribution of scanned objects. Finally, this paper also introduces recent developments related to the hard X-ray modulation telescope (HXMT) provided by THU. [Copyright &y& Elsevier]

Abstract: Multi-gap resistive plate chamber (MRPC) is a new kind of gas detector. It has good time resolution and high efficiency and has been adopted to construct the full barrel time-of-flight (TOF) detector for the STAR experiment at RHIC. The high rate TOF of CBM is also proposed to be assembled with MRPCs. Tsinghua University is a collaboration member of the two experiments and has made substantial progress on the R&D and production of MRPC. In this paper, we describe the development of low-resistivity glass and high rate MRPC, and the development of 1m long counter is also described. [Copyright &y& Elsevier]

Abstract: X-ray sources based on Thomson-scattering require strict synchronization between the laser pulse and the electron bunch. Jitter between the laser and the RF phase should be kept within a femtosecond scale to guarantee electron beam quality and the time of flight before impact with the terawatt laser pulse. A laser–RF synchronizer that uses the 36th harmonic of the laser repetition rate was built at Tsinghua University, and it has tested to have a less than 100-fs [10-Hz, 100-kHz] rms time jitter. An RF deflector cavity is used to verify the electron bunch pulse-to-pulse time jitter with respect to the RF accelerating phase in the same condition, and the result shows a 540-fs rms jitter. This paper discusses the synchronization experiment setup, as well as the time jitter measurements under different conditions. [Copyright &y& Elsevier]