[en] Energy saving in data centers is increasingly important along with the rapidly developing IT industry. This paper proposes an integrated cooling system for data centers which combines a heat pipe cooling cycle and a vapor compression cooling cycle. The operating mode of the system changes with the outdoor temperature. Key problems of the integrated system were solved such as the mix of the refrigerant and lubricant, the match of heat exchange areas and the durability of valves. A thermal equilibrium test was carried out to evaluate the system performance. Thermodynamic analyses based on experimental data show that the PUE (Power Usage Effectiveness) of data centers using the integrated heat pipe system can be 0.3 lower than using the conventional air cooling systems in cold areas like Beijing and Harbin. The energy saving potential of the integrated heat pipe system varies with seasonal and regional climate changes. - Highlights: • The system combines a heat pipe cycle and a vapor compression cycle. • The operating mode of the system changes with the outdoor temperature. • Several key problems in existing integrated systems are solved. • The new system significantly outperforms the conventional system by test results. • The energy saving potential of the system varies with climate changes.

[en] We report on the research of temperature influence on the performance of LaBr₃ detector. The result of temperature experiments show that energy resolution of LaBr₃ detector changed within ± 5% and peak-to-total ratio of LaBr₃ detector changed within ± 6% from -10 ℃ to 50 ℃, and the temperature changes during the experiment had no effect on the use of LaBr₃ detector. The channel of peak position changed obviously, thereby spectrum stabilization had to be done with the change of ambient temperature. (authors)

[en] The portable γ spectrometer can be used for identification of typical nuclides in the primary coolant and acquiring their activity concentrations in situ. The source-peak efficiency should be calibrated to ascertain the relationship between the net area under the characteristic peak of typical nuclide and its genuine activity concentration in the water sample. The efficiency calibration curve was acquired by measuring the mixed solution of ¹³³Ba, ¹³⁷Cs and ⁶⁰Co nuclides, and then ¹³⁷Cs standard liquid and simulated ¹³¹I standard liquid were measured respectively. Test results indicate that the spectrometer can identify typical nuclides ¹³⁷Cs and ¹³¹I, and the measuring relative error of activity concentration is less than 10%, which satisfies the requirement of measurement accuracy and sensitivity for fuel element rupture detection. (authors)

[en] A simple and practical kind of charge sensitive preamplifier was designed featuring lesser number of devices, simple debugging, good signal to noise ratio. It is applicable to the use as pre-amplification of ion injection semiconductor detector and gold silicon surface barrier semiconductor detector. (authors)

[en] Dipole operator s^¯σ_μνF^μνb requires the helicity flip in the involving quark states thus the breaking of chiral U(3)_Q×U(3)_d. On the other hand, the b quark mass generation is also a consequence of chiral U(3)_Q×U(3)_d symmetry breaking. Therefore, in many models, there might be strong correlation between the b→sγ and b quark Yukawa coupling. In this Letter, we use non-decoupling MSSM model to illustrate this feature. In the scenario, the light Higgs boson may evade the direct search experiments at LEPII or Tevatron while the 125 GeV Higgs-like boson is identified as the heavy Higgs boson in the spectrum. A light charged Higgs is close to the heavy Higgs boson which is of 125 GeV and its contribution to b→sγ requires large supersymmetric correction with large PQ and R-symmetry breaking. The large supersymmetric contribution at the same time significantly modifies the b quark Yukawa coupling. With combined flavor constraints B→X_sγ and B_s→μ⁺μ⁻ and direct constraints on Higgs properties, we find best fit scenarios with light stop of O(500 GeV), negative A_t around −750 GeV and large μ-term of 2–3 TeV. In addition, reduction in bb^¯ partial width may also result in large enhancement of ττ decay branching fraction. Large parameter region in the survival space under all bounds may be further constrained by H→ττ if no excess of ττ is confirmed at LHC. We only identify a small parameter region with significant H→hh decay that is consistent with all bounds and reduced ττ decay branching fraction. In the end, if current dark matter mostly consists of neutralino, direct detection experiments like XENON100 also puts stringent bound over this scenario with light Higgs bosons. The light stops which are required by flavor constraints can further enhance the scattering cross section

[en] Monte Carlo method was used to simulate the energy resolution of silicon photovoltaic detector for α-particle. The experiments showed that silicon photovoltaic detector had high energy resolution and detection efficiency. The influence of α-ray and α-ray was avoidable, so silicon photovoltaic detector was available to detecting α-particle. (authors)

[en] To address the problems in efficiency calibration of in-situ radioactivity measuring equipment, an approach to efficiency calibration was presented using point source in lieu of liquid volume source. Through Monte Carlo calculation, photoelectric count efficiency of lanthanum bromide detector to point and volume sources are obtained respectively and the relationship of calibration efficiency were established between point and volume sources for simplified use of efficiency calibration in practice. (authors)

[en] Multi-gap Resistive Plate Chamber (MRPC) is a new generation of gas detector with good timing and spacial resolution, whose technique is widely applied in some recent high energy (nuclear) physics experiments. In this letter, we report a long-strip two-end readout MRPC and its test beam performance. The measurements show that the long-strip performs a transmission line characteristic and the impedance is independent of the length of strip. The MRPC module we developed is presented to gain a timing resolution of ∼ 80 ps and a spacial resolution of ∼ 6.4 mm. The possible application of the MRPC is also discussed. (authors)

[en] Graphical abstract: Table of content Herein, through coordination-based post-synthetic strategy, microporous-mesoporous Zn-MOF-74 was easily functionalized by grafting coumarin on coordinatively unsaturated Zn(II) centers, yielding a series of coumarin-modified Zn-MOF-74 materials. The obtained samples afforded ultra-high adsorption capacity for UVI ions from water with maximum adsorption capacities as high as 360 mg/g (the record value in MOFs) and remarkable photo-switched capability of 50 mg/g. - Highlights: • This work shows the record uptake capability of U"V"I (360 mg/g) in MOFs. • This work shows, for the first time, photo-switching behaviour towards U"V"I in aqueous solution. • This work demonstrates a simple and effective method to largely enhance uptake capability of U"V"I. • This work demonstrates a distinct method to prepare photo-sensitive MOFs for photo-switching behaviour towards guest molecules. - Abstract: Driven by an energy crisis but consequently puzzled by various environmental problems, uranium, as the basic material of nuclear energy, is now receiving extensive attentions. In contrast to numerous sorbents applied in this field, metal-organic framework (MOFs), as a renovated material platform, has only recently been developed. How to improve the adsorption capacity of MOF materials towards U"V"I ions, as well as taking advantage of the nature of these MOFs to design photo-switched behaviour for photo-triggered storage/release of U"V"I ions are at present urgent problems and great challenges to be solved. Herein, we show a simple and facile method to target the goal. Through coordination-based post-synthetic strategy, microporous- mesoporous Zn-MOF-74 was easily functionalized by grafting coumarin on coordinatively unsaturated Zn(II) centers, yielding a series of coumarin-modified Zn-MOF-74 materials. The obtained samples displayed ultra-high adsorption capacity for U"V"I ions from water at pH value of 4 with maximum adsorption capacities as high as 360 mg/g (the record value in MOFs) and a remarkable photo-switched capability of 50 mg/g at pH value of 4. To the best of knowledge, and in contrast to the well-known photo-switched behaviour towards CO_2, dye (propidium iodide), as well as fluorescence observed in MOFs, this is the first study that shows a photo-switched behaviour towards radioactive U"V"I ions in aqueous solution.

[en] Inconel 718 is widely used in the aviation, space, automotive and biomedical industries because of its outstanding properties. Near-surface residual stresses that are induced by ball end milling in Inconel 718 can be crucial for the performance and service time of the machined parts. In this paper, the influences of cutting conditions, including the use of cutting parameters, cutting fluid and spindle angles, on the residual stresses in the ball end milling process of Inconel 718 alloy were investigated experimentally. X-ray diffraction measurements reveal that residual stress distributions are highly influenced by cutting parameters, especially the depth of cut and cutting speed. The milling operation with cooling induces more compressive stresses trend and the magnitude of the residual stresses increases in the tensile direction with the increase of spindle angles. These cutting induced effects were further discussed with respect to thermal- mechanical coupling theory and some observations made by optical microscopy. From this investigation, it is suggested that the machining process parameters are not the smaller the better for the control of residual stresses in the ball end milling process of Inconel 718. (author)