连续稳定循环的三效吸附式热泵两种工况下的COP值计算

设计了连续而又稳定循环的三效吸附式热泵单元－三效冷环。由于各吸附床的吸附循环之间具有先后连贯性，因此既避免了吸附床的过热，又消除了热泵输出端的不稳定工作状态，使得热泵系统的ＣＯＰ值Ｙｏｎｇ效率以及各吸附循环的效率比双效和单效系统均有显著提高。     

采用吸气管过热度调节的户式空气源采暖空调热水三用机

简要介绍户式空气源采暖空调热水三用机的项目背景、技术原理、技术路线。针对三用机的特殊技术要求,首次提出吸气管过热度的定义以及采用电子膨胀阀PID调节吸气管过热度的新概念,利用该调节方法研制一台三用机,并按行业标准进行型式试验检测。测试结果表明,三用机达到国标的节能等级,并可高效制热、低温采暖,以及实现高效率的采暖、空调、热水、空调＋热水等功能。     

Resolution enhanced light field near eye display using e‐shifting method with birefringent plate

Light field near eye displays (LFNED) can produce lightweight devices and address the accommodation–convergence conflict. However, low spatial resolution creates a poor immersive experience in LFNED. In addition, although many e‐shifting devices have been proposed to enhance resolution in projection system, yet those devices are too bulky to be applied in an LFNED to keep it lightweight. In this paper, a compact e‐shifting component is proposed to enhance image resolution in an LFNED by using a birefringent plate and twisted nematic switch cell. The proposed e‐shifting device is a flat and thin component with only 2.6 mm of thickness, which could be placed in the gap of an LFNED without increasing the thickness. The results show that the proposed components could be easily integrated in an LFNED with the result of resolution enhancement.     

Secure centralized spectrum sensing for cognitive radio networks

Spectrum utilization becomes more and more important while new communication techniques keep increasing and the spectrum bands remain finite. Cognitive radio is a revolutionary technology to make use of the spectrum more effectively. In order to avoid the interference to the primary user, spectrum sensing must be sensitive and reliable. Cooperative spectrum sensing (CSS) is one of the ways to increase the reliability of spectrum sensing. The information fusion technique is a key component of CSS. In this paper, we proposed a novel fusion scheme based on spatial correlation technique. We utilize geographical information with reputational weights to propose a two-level fusion scheme called secure centralized spectrum sensing (SCSS). The simulation results show that as the attackers present high density aggregation at some areas, the correct sensing ratio of SCSS is increasing as well even when the number of attackers is very large.     

New CO2 laser lines in the 11-μm wavelength region:new hot bands

Nineteen new laser lines in the 11-μm wavelength region have been observed in CW oscillation from a CO₂ laser with a high-Q, high-resolution cavity at a higher than usual current density. The frequency of each line has been measured using heterodyne frequency measurement techniques. Analysis of the frequencies shows that 15 lines are rotation-vibration transitions of the 01¹2-[11¹1,03¹1]_I band (the first sequence hot band) of the CO₂ molecule and four lines belong to the rotation-vibration transitions of the 02²1-[12 ²0, 04²0]_I band of CO₂     

Local inhomogeneity and surface degradation of Fe1.15Te and Fe1.03Te0.62Se0.38 single crystals

We have investigated the structural and magnetic properties of Fe_1.15Te and Fe_1.03Te_0.62Se_0.38 single crystals grown by slow cooling method using a specially designed double-walled quartz ampoule. X-ray diffraction reveals significant local inhomogeneity as a result of fractional substitution of Te site by Se in single crystal Fe_1.03Te_0.62Se_0.38. The existence of superconductivity is confirmed for Se substitution to the Te site of Fe_1.03Te_0.62Se_0.38 but with persistent Fe₇Se₈ impurity phase. Raman spectroscopy confirmed the surface structural instability when the samples were exposed to moderate laser irradiation in the atmospheric environment. With high intensity laser irradiation, Fe(Se,Te) compounds can be decomposed into Fe₂O₃ hematite phase.     

Wet oxidation of thin AlAs in cylindrical composite of GaAs/AlAs/GaAs

Lateral wet oxidation in a cylindrical composite, GaAs/AlAs/GaAs, with varying thickness of the AlAs layer has been investigated. The oxidation depth in AlAs was measured in the temperature range of 400–480 °C. At given temperature and time, the depth increases with the increase in thickness. The thickness effect was successfully interpreted based on the kinetic model of boundary layer diffusion. The results are consistent with the findings from early studies on samples of square and rectangular cross-sections with the same activation energy of the thermal process.     

Modeling and analyzing the effects of heat treatment on the characteristics of magnesium alloy joint welded by the tungsten-arc inert gas welding

The objective of this paper is to present the mathematical models for modeling and analysis of the effects of heat treatment on the characteristics of magnesium alloy joint welded by the tungsten-arc inert gas (TIG) welding. The process of heat treatment adopts the tempering process with varying processing parameters, including tempering temperature and tempering time. The microstructure and mechanical properties of the welded joint are considered in the characteristic evaluation and explored by experiment. An experimental plan of the face-centered central composite design (CCD) based on the response surface methodology (RSM) has been employed to carry out the experimental study. The results of analysis of variance (ANOVA) and comparisons of experimental data show that the mathematical models of the value of the maximum tensile strength and elongation are fairly well fitted with the experimental values with a 95% confidence interval. In the tempering process, the microstructure of welded joint in the weld bead displays two main microstructures of hcp-α-phase Mg and bcc-β-phase Mg₁₇Al₁₂. Results show that the average size and proportion of α-phase Mg grains decreases with the increase of the tempering time and temperature. But, the increase of the tempering time and temperature promote increasing the average size and proportion of β-phase Mg₁₇Al₁₂ grains. An increase in both the high value of tempering temperature and tempering time leads to an increase of the maximum tensile strength. The values of the elongation increase with increasing in both the value of tempering temperature and tempering time.     

Investigation of Ti Addition Effects on the Thickness of 55 pct Al-Zn-1.6 pct Si Coating by First-Principles Calculation

First-principles method was performed to predict the effect of Ti addition on thickness and adhesion of 55 pct Al-Zn-1.6 pct Si coating. The results of optimized geometric configurations, total energy, and charge distributions for the Ti substitution in Fe2Al5 and FeAl3 phases indicated Ti will grab electronic charges from Al atoms, form bonds with neighboring Al, which will reduce the growth of Fe-Al intermetallic layers, and finally enhance the adhesion of the coating/substrate. Furthermore, experiments were performed to validate the prediction results of first-principles successfully.