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Many subjects and objects are included into the zero-energy building investigation while the conventional optimal approach is suffering from its limitations. The boundary of energy balance and physic of zero-energy buildings in various regions highlighted with various architectural attributions require to be more investigated and assured. As reported by the statistics, it needs further integrating materials and installing costs in zero-energy buildings. In this paper, due to the increasing energy consumption in buildings, a new global multiple-criteria optimization model for zero-energy buildings, combining this model with the comprehensive assessment approach is conducted. The optimization design approaches for renewable energy structures included here are the multiple-criteria optimization by Enhanced Red Fox Optimization Algorithm on the initial design as concerns energy optimum models and costs, and the integration of Grey Multiple-Level Complete Assessment approach is employed to optimum model, which are the energy-conserving, solar energy application effectiveness, social and economic aspects. The optimum solution is proposed based on the chosen decision according to the global optimum model. This solution can help the engineer to design practical constructions. Finally, a multiple-objective optimal model for a case study placed in Beijing, China, is proposed to achieve an optimum design effect. Based on the study, efficient decisions can be made by designers with utilization of the proposed method. This design can easily be used in the considered real applications.

Given continued improvement in the thermal performance of building envelopes, interior disturbances caused by occupant behavior now have the greatest impact on building loads and energy consumption. The accurate calculation of interior load during design stage was emphasized in this paper, and a new method was proposed. Indoor occupants were considered as the core of interior disturbances, and the relationship with other interior disturbances was explored. The interior heat release was arbitrarily combined with the representative cooling load to be utilized in building cooling load calculation. Field surveys were conducted in three typical university buildings: an office building, a teaching building, and a library, located in a university in Tianjin, China. The oversized chillers supplying cooling for the buildings resulted from the over-estimating of the indoor occupant number and the power density of electric appliances. Through quantitative analysis, it was observed that the maximum representative interior loads were 196.43, 329.94, and 402.58 W/person, respectively, for the case buildings, at least 50% less than the empirical design data. Compared to the measured cooling load during the testing period, the accuracy of the modified cooling load was greater than 90%. This research is intended to serve as a reference for calculating and optimizing the design loads of cooling systems.

On the basis of ERBR (existing residential building retrofit) work in the 11th five-year period, energy efficiency retrofits for old residential buildings have been further promoted in northern regions of China during the 12th five-year period. ERBR projects are capable of not only achieving energy conservation and emissions reductions but also providing warmer rooms for residents during cold winters. Therefore, this project should be continued in northern regions of China following a long-term management mode. With the aim of exploring methods and mechanisms for the evaluation of the retrofit effect, an evaluation method was established with the application of the multi-level expert evaluation method. The evaluation indexes cover the aspects of policy mechanisms, financing modes and technical measures. A rewards and punishment mechanism according to the evaluation system was also suggested. Such an evaluation system can be used as a valuable reference for future implementation of energy efficiency retrofit work.

In order to promote energy efficiency and emission reduction, the importance of improving building energy efficiency received sufficient attention from Chinese Government. The heat metering and energy efficiency retrofit for existing residential buildings of 0.15 billion m2 in northern heating regions of China was initiated in 2007 and completed successfully at the end of 2010. This article introduced the background and outline of the retrofit project during the period of 11th five-year plan. Numerous achievements that received by retrofit such as environmental protection effect, improvement of indoor environment, improvement of heating system, investment guidance effect, promotion of relevant industries and increasing chances of employment were concluded. Valuable experience that acquired from the retrofit project during the period of 11th five-year plan was also summarized in this article. By analyzing the main problems emerged in the past, pertinent suggestions were put forward to promote a larger scale and more efficient retrofit project in the period of 12th five-year plan.

Phase change materials (PCM) can be applied in building envelops to conserve heat energy. Wallboards incorporated with PCM can automatically absorb indoor redundant heat, which can greatly reduce the load of HVAC systems and save electric energy. In experiments, a PCM wallboard room was constructed by attaching PCM wallboards, developed by incorporating about 26% PCM by weight into gypsum wallboards, to the surface of an ordinary wall. The transition temperature and latent heat of these PCM wallboards were tested by differential scanning calorimetry (DSC). The room testing was conducted to determine the latent heat storage of PCM wallboards. Through experiments, it could be proved that DSC can effectively predict the performance of a full-scale installation of PCM wallboards. Compared with an ordinary room, it was found that the PCM wallboard room could greatly reduce the energy cost of HVAC systems and transfer electric power peak load to valley.

Astronomical telescopes with increasingly large apertures are required to upgrade the limit of diffraction and collect the light efficiently for the purpose of observing fainter and more remote objects with higher angular resolution. However, it is universally believed that traditional techniques of manufacturing, polishing and measuring large glass mirrors will soon face some practical challenges. Therefore, 10-m class or larger ground-based telescopes will need to employ arrays of several smaller segments to assemble into a large primary mirror. For a telescope with segmented mirrors, the piston errors between segments must be adjusted to nearly zero according to the requirements in order to be integrated into a single optical surface, which is known as co-phasing. One of the current co-phasing techniques, which has been successfully applied to Keck telescopes, employs an integration of edge sensors to detect the mirror shapes in real time with an optical phasing sensor to offer zero references for these sensors regularly. Another technique is demonstrated by use of a pyramid wavefront sensor (PWFS) to align and co-phase segmented mirrors in an active control close-loop with a single measurement. The co-phased best flat positions of segments are used as the zero references in order to measure the interaction matrix between the PWFS and the segmented mirrors. So it must be addressed that how the zero co-phasing reference is calibrated with high precision in a large capture range on the issues of co-phasing segmented mirrors. The current methods either lack accuracies, or just measure piston errors correctly in a small range. In order to solve the problem, a zero co-phasing reference calibration method based on dispersed interferogram is proposed. Specifically, the idea of the method is to define an appropriate cost function which is used to evaluate the piston errors between segments. Then it will be easy to determine the zero co-phasing reference position while all the cost function values are calculated based on the dispersed interferogram data with different piston errors inside the capture range. The proposed cost function is defined as the sum of the ratios of the second peak to the third peak of each of the columns of the two-dimensional dispersed interferogram, whose intensity distribution is along the dispersion direction. The precision and dynamic range of the method are analyzed theoretically and studied by simulations. Furthermore, the optical experiment is set up to demonstrate the efficacy of the method. In the experiment a scanning procedure is applied to one mirror and the dispersed interferograms between two mirrors with different piston errors are obtained. And then, the cost functions of these dispersed interferograms are computed through which the zero co-phasing reference position is located. The experimental results prove that the zero co-phasing reference between two mirrors can be calibrated within an accuracy of about 10 nm by making use of the proposed method. In addition, the novel method solves the problem of 2 ambiguity. Besides its sub-millimeter level wide capture range, this new co-phasing detecting method provides a helpful reference for relevant studies.

As for the large energy consumption of the residential buildings in heating seasons in winter, energy efficiency retrofit has been carried in China. The energy efficiency retrofit for the existing buildings in heating areas is a complex project related to the buildings, heating system and heat users. The key problem in the energy efficiency retrofit — the envelope insulation was analyzed in this paper. A typical residential building in severe cold area in China was selected. Building energy consumption in different conditions of envelope insulation was simulated with DeST-h software. The relation formula between the building heat consumption, dynamic investment recovery period of the building envelope retrofit were fitted with Maple software. The mathematical model of the heat consumption index and dynamic investment were established. And the insulation layer thickness to the minimum dynamic investment recovery period was determined.

Based on the jet theory of dynamic mechanism, the jet flow of the convergent air contain was studied. According to similarity theory, jet theory, the relevant parameters of the air curtain, and practical experience, a generator of the convergent air curtain was designed. The flow pattern of the convergent air curtain was analyzed, and it was divided into three regions, which were noninterference region, mixed turbulence region, and free diffusion region. The three regions were analyzed theoretically. The mathematical expressions of the axis air velocity, air flow of the cross section, and flow coefficient were obtained, which provide a basis for analyzing the convergent air curtain.

Main factors which influenced the energy consumption of residential buildings were analyzed. DeST-c software was used to simulate a typical residential building in heating area in China, and the heat consumption index of the building under different insulation-layer thickness was investigated. It is found that building heat consumption index shows a downward trend with the increase of insulation-layer thickness. But this downward trend will gradually become slow. After increasing to a certain extent of the insulation-layer thickness, the decreasing in the heat consumption index will be very limited with the increase of the insulation-layer thickness. So energy conservation potential by an increase in the insulation-layer thickness is limited.

For the Fizeau optical interferometric telescope system, the co-phasing detection of piston errors between sub-apertures plays an important role in realizing the high resolution of system. In this paper, the relationship between piston error and the main peak displacement of monochromatic interferogram of two sub-aperture system is analyzed based on physical principles, then the piston error detecting method is developed and clarified based on their linear relationship in the range of one wavelength. Furthermore, an innovative co-phasing detecting method based on grating dispersed interferogram with bandwidth light source is proposed, and its feasibility, detecting precision and dynamic range are analyzed in theory and studied in simulation. The results prove that with this method, the piston error between the two sub-apertures of the system can be soundly detected and its measuring error is less than 20 nm while the piston error is not more than 50 μm. In addition, the novel method solves the problems of 2π ambiguity and direction determination that might exist within some other detecting methods. Besides its millimeter level dynamic range, this new co-phasing detecting method provides a new way and an effective reference for in-depth research of co-phasing detecting techniques.

An asymmetric quantum well (AQW) is designed to emit a terahertz (THz) wave by using difference frequency generation (DFG) with the structure of GaAs/Al0.2Ga0.8As/Al0.5Ga0.5As under a doubly resonant condition. It is found that the second-order nonlinear susceptibility χ(2) varies with the two pump wavelengths, and it can reach the peak value of 1.61 μm/V when the wavelengths are given as λp1 = 9.756 μm and λp2 = 10.96 μm, respectively. The numerical results show that the refractive index of one pump wave in the AQW is concerned with not only its own wavelength but also the other wavelength. Phase-matching inside the AQW can be obtained through the tuning of the two pump wavelengths.

The parametric gain of a terahertz wave parametric oscillator (TPO) is analyzed. Meanwhile the expression of TPO threshold pump intensity is derived and theoretically analyzed with different factors. The effective interaction length between the pump wave and Stokes wave is calculated, and particular attention is paid to the coupling efficiency of the pump wave and Stokes wave. Such an analysis is useful for the experiments of TPO.

This telescope was designed for determining the trigonometric parallaxes of faint stars. The otpical configuration is a Ritchey-Chretien system and has only a f/10 Cassegrain focus for photographic work.