[en] Unitary operations are physically implementable. We further the understanding of such operators by studying the possible forms of nonlocal unitary operators, which are bipartite or multipartite unitary operators that are not tensor product operators. They are of broad relevance in quantum information processing. We prove that any nonlocal unitary operator of Schmidt rank three on a d_A×d_B bipartite system is locally equivalent to a controlled unitary. This operator can be locally implemented assisted by a maximally entangled state of Schmidt rank min(d_A²,d_B) when d_A≤d_B. We further show that any multipartite unitary operator U of Schmidt rank three can be controlled by one system or collectively controlled by two systems, regardless of the number of systems of U. In the scenario of n-qubit, we construct non-controlled U for any odd n≥5, and prove that U is a controlled unitary for any even n≥4

[en] Fully kinetic-particle simulations and hybrid simulations have been utilized for decades to investigate various fundamental plasma processes, such as magnetic reconnection, fast compressional waves, and wave-particle interaction. Nevertheless, due to disparate temporal and spatial scales between electrons and ions, existing fully kinetic-particle codes have to employ either unrealistically high electron-to-ion mass ratio, me/mi, or simulation domain limited to a few or a few ten's of the ion Larmor radii, or/and time much less than the global Alfven time scale in order to accommodate available computing resources. On the other hand, in the hybrid simulation, the ions are treated as fully kinetic particles but the electrons are treated as a massless fluid. The electron kinetic effects, e.g., wave-particle resonances and finite electron Larmor radius effects, are completely missing. Important physics, such as the electron transit time damping of fast compressional waves or the triggering mechanism of magnetic reconnection in collisionless plasmas is absent in the hybrid codes. Motivated by these considerations and noting that dynamics of interest to us has frequencies lower than the electron gyrofrequency, we planned to develop an innovative particle simulation model, gyrokinetic (GK) electrons and fully kinetic (FK) ions. In the GK-electron and FK-ion (GKe/FKi) particle simulation model, the rapid electron cyclotron motion is removed, while keeping finite electron Larmor radii, realistic me/mi ratio, wave-particle interactions, and off-diagonal components of electron pressure tensor. The computation power can thus be significantly improved over that of the full-particle codes. As planned in the project DE-FG02-05ER54826, we have finished the development of the new GK-electron and FK-ion scheme, finished its benchmark for a uniform plasma in 1-D, 2-D, and 3-D systems against linear waves obtained from analytical theories, and carried out a further convergence test and benchmark for a 2-D Harris current sheet against tearing mode and other instabilities in linear theories/models. More importantly, we have, for the first time, carried out simulation of linear instabilities in a 2-D Harris current sheet with a broad range of guide field BG and the realistic mi/me, and obtained important new results of current sheet instabilities in the presence of a finite BG. Indeed the code has accurately reproduced waves of interest here, such as kinetic Alfven waves, compressional Alfven/whistler wave, and lower-hybrid/modified two-stream waves. Moreover, this simulation scheme is capable of investigating collisionless kinetic physics relevant to magnetic reconnection in the fusion plasmas, in a global scale system for a long-time evolution and, thereby, produce significant new physics compared with both full-particle and hybrid codes. The results, with mi/me=1836 and moderate to large BG as in the real laboratory devices, have not been obtained in previous theory and simulations. The new simulation model will contribute significantly not only to the understanding of fundamental fusion (and space) plasma physics but also to DOE's SciDAC initiative by further pushing the frontiers of simulating realistic fusion plasmas.

[en] Highlights: • An ejector-assisted loop heat pipe with a flat evaporator (ELHP) is proposed. • The ejector is used to remove the generated vapor in the CC due to the heat leak. • Performances of the ELHP and basic loop heat pipe (BLHP) are compared. • Comparisons show that operating temperature of the ELHP is lower than that of the BLHP. • Compared with the BLHP, the condenser length of ELHP can be decreased significantly. - Abstract: This paper proposes an ejector-assisted copper–water loop heat pipe with a flat evaporator (ELHP) for applications in electronic cooling. In the ELHP, the ejector is used to remove the generated vapor in the compensation chamber due to heat leaks through the wick, which could eliminate the need for the subcooling liquid supplied to the compensation chamber and improve the loop heat pipe performances. The steady-state performance of ELHP is simulated based on an established mathematical model and compared with the basic loop heat pipe with a flat evaporator (BLHP). The simulation results show that the operating temperature of the ELHP can be lower than that of the BLHP under the same heat load condition. Since the working fluid subcooling zone in the ELHP condenser is not required, the total length of the pipe-in-pipe type condenser also can be decreased by 24.4–34.8% when compared with that of the BLHP under given operating conditions. In addition, the effects of the thickness of the wick, the total length of the condenser, the inner diameter of the vapor line and the mass flow rate and inlet temperature of the cooling water on the performances of the ELHP are also evaluated in this study. These simulation results indicate that the ELHP can achieve a better performance than BLHP, which could be beneficial to the applications in electronic cooling.

[en] Objective: To characterize the features of proton magnetic resonance spectroscopy (¹H-MRS) on amyotrophic lateral sclerosis (ALS) and its correlations with clinical scale. Methods: Fifteen patients with definite or probable ALS and 15 age and gender matched normal controls were enrolled. ¹H-MRS was performed on a 3.0 T GE imaging system (GE Medical System, Milwaukee, Wisconsin, USA). TE-averaged point resolved selective spectroscopy was used. N-acetylaspartate (NAA), creatine (Cr), Glu and Glx (glutamate + glutamine) values of subcortical motor area and posterior limb of the internal capsule were acquired, t test was used to compare differences between groups, the correlations between the above values and clinical scale were analyzed. Results: The motor area and posterior limb of the internal capsule in ALS patients had significantly lower NAA/Cr (1.91±0.34, 1.53±0.17) compared with normal subjects (2.23±0.33, 1.66±0.07) (t=4.25,2.90,P=0.00,0.01). ALS patients had significantly higher Glu/Cr (0.34±0.05, 0.29±0.06) and Glx/Cr (0.40±0.04, 0.33±0.06), compared with normal subjects (0.30±0.03,0.25±0.04) and (0.32±0.05,0.26±0.03) (t=2.56, 2.40,7.34,5.30, P=0.02,0.03,0.00,0.00). The Norris scale of ALS patients were 57±8, ALSFRS were 29±4. The Norris scale was negatively correlated with Glx/Cr of primary motor cortex by lineal correlation analysis (r=-0.75, P=0.00), while ALSFRS had no correlation with Glx/Cr. Conclusions: Neuronal loss and Glu + Gln increase can be detected by using proton MRS in ALS patients. ¹H-MRS is an useful tool in reflecting the characteristic changes of metabolite in ALS. (authors)

[en] Using first-principles calculations, we investigate the stabilities of He and He_n-vacancy (He_nV) clusters in α-Fe and W. Vacancy formation energies are 2.08 eV in α-Fe and 3.11 eV in W, respectively. Single He in both α-Fe and W prefers to occupy the tetrahedral interstitial site. We recalculated the He solution energy considering the effect of zero-point energy (ZPE). The ZPEs of He in α-Fe and W at the tetrahedral (octahedral) interstitial site are 0.072 eV (0.031 eV) and 0.078 eV (0.034 eV), respectively. The trapping energies of single He at vacancy in α-Fe and W are −2.39 eV and −4.55 eV, respectively. By sequentially adding He into vacancy, a monovacancy trap up to 10 He atoms distributing in the vacancy vicinity. Based on the above results combined with statistical model, we evaluate the concentrations of all relevant He_nV clusters as a function of He chemical potential. The critical He_nV concentration is found to be ∼10⁻⁴⁰ (atomic) at the critical temperature T = 600 K in α-Fe and T = 1600 K in W, respectively. Beyond the critical He_nV concentrations, considerable He_nV aggregate to form He_nV_m clusters. By further growing of He_nV_m, the He_nV_m clusters grow bigger resulting in the larger He bubble formation

[en] Highlights: • B20 and diesel exhibit similar spray tip penetration and angle. • Change in orientation of spray shapes observed with different fuels. • B100 shows poor air fuel mixing compared to B20 and diesel. • Diesel shows higher equivalence ratio compared to B20 and B100. - Abstract: In this study, the fuel spray characteristics and air-fuel mixing process of waste cooking oil biodiesel (B100) and its blend with diesel (B20) were investigated and compared with diesel fuel. Spray characteristics such as spray tip penetration, spray angle, spray velocity and spray morphology were investigated under high injection and ambient pressure conditions using a constant volume spray chamber. The air-fuel mixing process was analysed using empirical relations like fuel volume, mass of air entrained within the spray and equivalence ratio. The results shows that B100 has higher spray tip penetration and velocity but narrow spray angles due to high viscosity and large momentum possessed by B100 compared to B20 and diesel fuels. The deviation in spray tip penetration reduces under high ambient pressure. The spray angle shows no change under various injection pressures; however it increases significantly under high ambient pressure. The spray shape is affected by the cavitation inside the injector nozzle holes. The fuel volume and amount of air entrainment within the spray showed that B100 exhibits poor air-fuel mixing compared to B20 and diesel fuels. Nevertheless, the equivalence ratio along the axial direction of spray reveals that the B100 has lean equivalence ratio compared to B20 and diesel fuel due to the presence of inherent oxygen content in its structure. A numerical simulation was conducted using new hybrid spray model implemented in KIVA4 and found that the results obtained from the simulation were in good agreement with the empirical results calculated from the experiments

[en] The solid fluorescence spectral properties of uranium in phosphates systems have been observed. The NaH₂PO₄: U system has been found to be an efficient green phosphor. The luminescence mechanism of the phosphor has been discussed. The crystal structure of NaH₂PO₄: U system under different conditions was also studied. Over a wide range of ignition temperatures (200 ∼ 600 C degree), the system with mass ratio of U/NaH₂PO₄ below 10^-3 transforms into NaPO₃: U crystal, which emits strong fluorescence. The system is non-crystalline with decreasing fluorescence intensity when the ignition temperature is higher than 650 C degree. The NaPO₃ crystal lattice has distorted as the mass ratio of U/NaH₂PO₄ of the system greater than 10^-2

[en] This paper reports a simple one-step hydrothermal route for the preparation of hierarchical nanosheets-based ZnO microstructures and their application to dye-sensitized solar cells. The morphologies of the products were controlled by the dosage of the reactants. Their physical characteristics were detected by X-ray diffraction, a field-emission scanning electron microscope and a surface analyzer. It is proved that the sample of ZnO microspheres with larger surface area and stronger light-trapping capacity since the superiority of their entirely spherical structures exhibits better photoelectrochemical properties than the mixtures of ZnO microspheres and ZnO microflowers. A dye-sensitized solar cell assembled by the ZnO microspheres as photoanode shows an energy conversion efficiency of 2.94% after surface modification by tetrabutyl titanate solution at 90 ^°C. This result is over 1.6 times higher than the non-modified cell fabricated by the ZnO microspheres on the basis of the external improvement and the stability enhancement for the dye-sensitized ZnO photoanode. - Graphical abstract: Influences on energy conversion efficiency of the dye-sensitized solar cells assembled by decorating hierarchical nanosheets-based ZnO microstructures with tetrabutyl titanate solution at different temperatures. Display Omitted - Highlights: • Hierarchical nanosheets-based ZnO microstructures were controllably synthesized. • The ZnO microspheres show good optical and electrochemical properties. • The ZnO microspheres were modified by C₁₆H₃₆O₄Ti solution. • Remarkable increase of conversion efficiency is observed after surface modification

[en] Highlights: • A better understanding of the nitride layer formed on titanium alloy. • Search for titanium treated with high wear-resistance and low cost. • Crack-free nitride layer was formed by the GTAW method. - Abstract: In this investigation, titanium nitride (TiN) reinforcements are synthesized in situ on the surface of Ti–6Al–4V substrates with gas tungsten arc welding (GTAW) process by different methods to add nitrogen, nitrogen gas or TiN powder, to titanium alloys. The results showed that if nitrogen gas was added to titanium alloys, the TiN phase would be formed. But if TiN powder was added to titanium alloys, TiN + TiN_x dual phases would be presented. The results of the dry sliding wear test revealed that the wear performance of the Ti–6Al–4V alloy specimen coated with TiN or TiN + TiN_x clad layers were much better than that of the pure Ti–6Al–4V alloy specimen. Furthermore, the evolution of the microstructure during cooling was elucidated and the relationship among the wear behavior of the clad layer, microstructures, and microhardness was determined

[en] In order to control or suppress edge localized modes in nuclear fusion reactors, an accurate pedestal pressure profile measurement is necessary. A line integrated backward Thomson scattering measurement is an attractive method because of its long scattering length. Assuming that the first mirror is located far from the plasma to avoid degradation of the mirror due to erosion and impurity deposition, the measurement accuracies of density and temperature and pressure are estimated. For the target plasma, we adopt the pedestal profile with the shoulder density of 10¹⁹ - 10²⁰ m⁻³ and the dimensions of the JA DEMO reactor. The calculation results show that, the Poisson noise due to finite detected scattered photon number is much larger than that due to bremsstrahlung emission. In addition, noise is enhanced by reconstruction process. The resultant total noise levels of reconstructed density, temperature and pressure profiles are at most 1.5%, 3%, 3%, respectively in the steep gradient region, and this method is feasible in the reactor. (author)