[en] Considerable amounts of voids are often observed in micro joints used in microelectronic industry. To devise proper strategies to suppress the formation of these voids requires an understanding of the void formation mechanism. The Ni/Sn/Ni system is used in this study to determine the effects of surface diffusion and reaction-induced volume shrinkage. It is confirmed out that the reaction-induced volume shrinkage plays an important role. Surface diffusion has a strong effect on the surface morphology of the micro joints. Additionally, for the first time the three dimensional void distribution in a micro joint is uncovered by using sequentially ion beam cross-sectioning. - Highlights: • Solder surface diffusion was an important factor for surface morphology. • Reaction-induced volume shrinkage was dissipated mainly by formation of voids. • The void ratio in micro joints was estimated by sequential FIB cross-sectioning.

[en] Different adsorbents, such as physical, chemical and composite adsorbents are analyzed. Three types of working pairs, activated carbon-methanol, chemical adsorbent-ammonia and composite adsorbent-ammonia can be used for adsorption ice makers on fishing boats. The advantages, disadvantages and performances of three types of adsorption ice makers, with activated carbon-methanol, CaCl₂-NH₃ and compound adsorbent (made by CaCl₂ and activated carbon)-NH₃ as adsorption pairs, are compared at the condition of two bed systems. The activated carbon-methanol ice maker shows the advantage of reliable safety, and the composite adsorption ice maker shows the best adsorption performance. The cooling power of 20.32 kW can be obtained from the composite adsorption ice maker when the volume for each adsorber is 0.288 m³, which is about 10 times that of the physical adsorption ice maker and 1.38 times that of the chemical adsorption ice maker

[en] AC losses of NbTi-Cu and NbTi-Cu-CuNi superconducting composite magnets have been measured by means of an electronic integration technique. The experimental results are presented and their qualitative comparisons are made. It is shown within our experimental range that: (1) AC losses of NbTi-Cu composite magnet are proportional to the peak value and exciting velocity of the magnetic field; and (2) AC losses of NbTi-Cu-CuNi composite magnet are also proportional to the peak value of the magnetic field, but decrease as exciting velocity increases

[en] The brain contains its own angiotensin II (AII) system. To better understand the role of central AII in cardiovascular regulation, we used 125I-[Sar1, Ile8]-AII (125I-SI-AII), radioactive AII antagonist, to autoradiographically localize putative AII receptor binding in many parts of the central nervous system of the spontaneously hypertensive (SHR) and normotensive Wistar-Kyoto (WKY) rats. With 125I-SI-AII binding on brain membrane preparations. Scatchard analysis indicated that Kd values were from 0.10 +/- 0.04 nM to 0.13 +/- 0.05 nM, whereas Bmax values (femtomol/mg protein) were found to be from 6.95 +/- 1.60 to 15.52 +/- 4.99 among brain regions studied. Various SI-AII receptor binding activities among brain regions revealed in this study were therefore most likely due to differences in AII receptor density with high affinity binding of 125I-AII. Using 125I-SI-AII, specific binding for SI-AII was found in the nucleus tractus solitarius (NTS), paraventricular hypothalamic nucleus (PVN), subfornical organ (SFO), suprachiasmatic nucleus (SCN), area postrema, the dorsal motor nucleus of the vagus (DMX), and the nucleus of spinal tract of the trigeminal system (NSV). With quantitative receptor autoradiography in conjunction with radioactive standards, we have observed that the NTS possesses the highest SI-AII binding, followed by the PVN, SFO, NTS, DMX, and NSV. No significant differences were observed between the SHR and WKY rats in the SI-AII binding within the SFO, PVN and NTS. However, SHR at early hypertensive (7 weeks) and established hypertensive (16 weeks) stages contained significantly higher SI-AII bindings in the NSV, as compared to age-matched WKY rats

[en] Highlights: • Exhaust gas deep-recovery and thermoelectric generator are applied in CCHP system. • Electric output of TEG changes from 0.231 kW to 1.18 kW. • Total recoverable waste heat increases by 13–16%. • ESR, CSR and PEE are improved to 0.304, 0.417, and 0.944, respectively. • The total investment increment of system is about 11%. - Abstract: Combined cooling, heating and power (CCHP) systems are thought to be highly efficient in energy utilization. But there are still potentials to further improve system performance. This work proposed a CCHP system based on internal combustion engine (ICE) for power generation, refrigeration and domestic hot water production. Thermoelectric generator (TEG) and condensing heat exchanger are applied to efficiently recover the exhaust gas waste heat of ICE. All the energy flows are designed based on energy cascading utilization principle. Basing on the test results of a 16 kW ICE, CCHP system characteristics are investigated by simulation from idling condition to full load condition. Especially, the part load performance of TEG and absorption chiller are simulated and discussed. The feasible operating zone of ICE and feed water flow rate are figured out to keep the domestic hot water temperature within a certain range. Results show that the primary energy efficiency of system can reach 0.944, thanks to the condensing heat recovery from exhaust gas. The primary energy saving ratio and cost saving ratio can reach 0.304 and 0.417, respectively. Considering some more equipment is incorporated, the total investment increment is about 11.1%

[en] The collective excitations in AA-stacked bilayer graphene for a perpendicular electric field are investigated analytically within the tight-binding model and the random-phase approximation. Such a field destroys the uniform probability distribution of the four sublattices. This drives a symmetry breaking between the intralayer and interlayer polarization intensities from the intrapair band excitations. A field-induced acoustic plasmon thus emerges in addition to the strongly field-tunable intrinsic acoustic and optical plasmons. At long wavelengths, the three modes show different dispersions and field dependence. The definite physical mechanism of the electrically inducible and tunable mode can be expected to also be present in other AA-stacked few-layer graphenes. -- Highlights: •The analytical derivations are performed by the tight-binding model. •An electric field drives the non-uniformity of the charge distribution. •A symmetry breaking between the intralayer and interlayer polarizations is illustrated. •An extra plasmon emerges besides two intrinsic modes in AA-stacked bilayer graphene. •The mechanism of a field-induced mode is present in AA-stacked few-layer graphenes

[en] High-fidelity simulation of nuclear reactor accidents such as the rupture of a main steam line in a pressurized water reactor (PWR) requires three-dimensional core hydrodynamics modeling because of the strong effect channel cross flow has on reactor kinetics. A parallel nested Krylov linear solver was developed and implemented in the RETRAN-03 reactor systems analysis code to make such high-fidelity core modeling practical on engineering workstations. Domain decomposition techniques were also applied to the RETRAN-03 solution algorithm and demonstrated using a distributed memory parallel computer. Applications were performed for a four-loop Westinghouse PWR steam-line-break accident, and performance improvements of over a factor of 30 were achieved for models with 25 flow channels in the core. Larger models (e.g., 104-core channels), previously inaccessible because of memory limitations, were also solved with practical execution times

[en] The stability of a natural circulation boiling loop is of great importance and interests for both academic researches and many industrial applications, such as next generation boiling water reactors. The present study investigated the thermal-hydraulic oscillation behavior in a low pressure two-phase natural circulation loop at low powers and high inlet subcoolings. The experiments were conducted at atmospheric pressure with heating power ranging from 4 to 8 kW and inlet subcooling ranging from 27 to 75 deg. C. Significant oscillations in loop mass flow rate, pressure drop in each section, and heated wall and fluid temperatures are present for all the cases studied here. The oscillation is typically quasi-periodic and with flow reversal with magnitudes smaller than forward flows. The magnitude of wall temperature oscillation could be as high as 60 deg. C, which will be of serious concern for practical applications. It is found that the first fundamental oscillation (large magnitude oscillation) frequency increases with increase in heated power and with decrease in inlet subcooling. (author)

[en] In this study, a small scale hybrid solar heating, chilling and power generation system, including parabolic trough solar collector with cavity receiver, a helical screw expander and silica gel-water adsorption chiller, etc., was proposed and extensively investigated. The system has the merits of effecting the power generation cycle at lower temperature level with solar energy more efficiently and can provide both thermal energy and power for remote off-grid regions. A case study was carried out to evaluate an annual energy and exergy efficiency of the system under the climate of northwestern region of China. It is found that both the main energy and exergy loss take place at the parabolic trough collector, amount to 36.2% and 70.4%, respectively. Also found is that the studied system can have a higher solar energy conversion efficiency than the conventional solar thermal power generation system alone. The energy efficiency can be increased to 58.0% from 10.2%, and the exergy efficiency can be increased to 15.2% from 12.5%. Moreover, the economical analysis in terms of cost and payback period (PP) has been carried out. The study reveals that the proposed system the PP of the proposed system is about 18 years under present energy price conditions. The sensitivity analysis shows that if the interest rate decreases to 3% or energy price increase by 50%, PP will be less than 10 years. (author)

[en] Titanium nitride films have been deposited on the surfaces of tungsten, 304 stainless steel and 2014-T6 aluminium alloy using the hollow-cathode-discharge (HCD) ion plating technique. The characterization of titanium nitride films has been analysed, mainly by using high resolution pulsed-laser atom-probe field-ion microscopy (FIM) and the X-ray diffraction (XRD) technique. XRD indicates that the film consists predominantly of the TiN phase. The atom-probe spectrum is also found to contain molecular ions of this species. Depth profiling discloses the existence of a rather thin interface of about 15 atomic layers and also reveals that the impurity TiO is concentrated not only in this interface but also near the top film surface. Both surface temperature and nitrogen gas pressure as well as energetic ion impacts have an effect on the film deposition. Thus it is proposed that an energy enhanced and surface catalysed reaction is predominant in the formation of titanium nitride compounds during film growth. (author)