Sustainable Supply Model Design of Public Rental Housing —Case Study of Chongqing

Public rental housing is an important governmental project. Within the next three years, Chongqing municipal government proposes building 40×10⁶ m² of public rental housing to solve the housing problem for 2 million people. Many problems of sustainability have happened in long-term large-scale construction, including gradually-slow renting progress, the shortage of funds, public rental housing community facilities are retrograde, and the selected sites are at the city’s edge. This paper analyzes the Chongqing public rental housing situation from the perspective of sustainable public rental housing supply, putting forward a sustainable supply model that is suitable for Chongqing, and then calculates their portion.     

Sustainable Supply Model Design of Public Rental Housing —Case Study of Chongqing

Public rental housing is an important governmental project. Within the next three years, Chongqing municipal government proposes building 40×10⁶ m² of public rental housing to solve the housing problem for 2 million people. Many problems of sustainability have happened in long-term large-scale construction, including gradually-slow renting progress, the shortage of funds, public rental housing community facilities are retrograde, and the selected sites are at the city’s edge. This paper analyzes the Chongqing public rental housing situation from the perspective of sustainable public rental housing supply, putting forward a sustainable supply model that is suitable for Chongqing, and then calculates their portion.     

A Review on Shale Gas Development in Fuling

The Fuling Marine Shale Deposit contains vast gas resources. Due to tectonic activities, complex surface and geological conditions, significant differences make it unlike that of North America. Thus, it is not suitable to completely copy the technology and the development model from North America. Therefore we need engineering technology and a business development model fit for Fuling Shale Gas Development (FSGD). Through difficulties and characteristics analysis of the shale gas development area, we determined geological engineering design methods and integrated workflow, established a series of the core technologies, including horizontal well drilling with long laterals, staged fracturing and completion technology, developed main fluids, tools and equipment, put forward “well factory” mode in mountain region and “full cycle learning and system optimization” management methods. Break through was made in China’s first large-scale shale gas fields commercial development. By the end of 2014, production capacity reached 25 × 10⁸ m³/a, and cumulative gas production reached 12.24 × 10⁸ m³, which made a solid foundation to build production capacity of 50 × 10⁸ m³/a in 2015 and 100 × 10⁸ m³/a in 2017. Not only has FSGD established a demonstration for the other shale gas fields’ development, but also will be taken as reference to other large and extra-large construction projects of the industry.     

Neutron irradiation of Nb3Sn and NbTi multifilamentary composites

NbTi and Nb3Sn multifilamentary composites have been irradiated with fast-neutrons at 60 ± 5°C to fluences of 1.2×10²⁰n/cm²(E > 1 MeV). The NbTi samples show only a moderate reduction of Icas a function of neutron fluence in an applied field of 40 kG. Reductions in Icwere observed for fluences greater than 3 × 10¹⁷n/cm²and saturate at 18% for fluences greater than 3-4 × 10¹⁹n/cm². The Nb3Sn composites showed large neutron radiation induced changes in Tc, Icand Hc2. Reductions in Tcwere observed for fluences greater than 7 × 10¹⁷n/cm². No measurable changes in Ic(40 kG) were observed below 10¹⁸n/cm². Between 2 and 3×10¹⁸n/cm², however, there is an apparent threshold where a very rapid reduction in Ic(40 kG) is initiated. At the threshold the decrease in Tcis 13%. Between the threshold and 1.1 × 10¹⁹n/cm², I2(40 kG) has been reduced to 4% of the unirradiated value. These changes in superconducting properties in NbTi and Nb3Sn are analyzed in terms of the radiation induced defects. The impact of the response to irradiation of both materials on their applications in fusion reactor magnets is discussed.     

Microstructural changes in oxygen-irradiated zirconium-based alloy characterised by X-ray diffraction techniques

We have carried out irradiation with 116 MeV O⁵⁺ ions on Zr–1Sn–1Nb–0.1Fe (ZIRLO) alloy at different doses and the microstructural parameters of the irradiated samples have been characterised by X-ray Diffraction Line Profile Analysis (XRDLPA). The average volume-weighted and surface-weighted domain size, microstrain and dislocation density have been estimated as a function of dose. There was a drastic decrease in domain size from unirradiated sample to the sample at a dose of 1 × 10¹⁷ O⁵⁺/m², but these values saturated with increasing dose of irradiation. The values of microstrain were found to increase with dose. The dislocation density increased almost by an order of magnitude for the samples irradiated with 1 × 10¹⁸ O⁵⁺/m² and 5 × 10¹⁸ O⁵⁺/m² as compared to the unirradiated samples.     

Concepts and limitations of macroparticle accelerators using travelling magnetic waves

The concept of an accelerator using a travelling magnetic wave that acts on magnetized projectiles is discussed. Although superconductors potentially may be good projectile material, their low critical temperature makes them unsuitable, Among ferromagnetic materials, dysprosium seems superior. For stable suspension and guidance, a high conductivity (preferrably superconducting) guide sheet is necessary. Magnetic field gradients of 10⁹A/m²travelling at 10⁶m/s should be achievable using present state-of-the-art components; resulting accelerations are ≳500 km/s². A linear accelerator for final speeds of 50 km/s needs a length of 2.5 km. Guidance forces sufficient to produce acceleration of2 times 10^{6}m/s²allow circular accelerators of reasonable size to achieve hypervelocities for small (50-100 mg) projectiles. An accelerator of 170-m diam would surpass the best results from light gas guns. Travelling waves suitable for accelerations of 10⁴m/s²can be produced without switching by means of flux displacing rotors and may be easily adapted to circular accelerators.     

Practice and understanding of developing new technologies and equipment for green and low-carbon production of oilfields

The core of China’s low-carbon development includes optimization of industrial structure, clean energy technologies, emission reduction technologies, and innovation of relevant systems and institutions. China National Petroleum Corporation (CNPC) has always been a proactive participant in developing low-carbon economy, shouldering the responsibilities of safeguarding oil and gas supply, conserving energy, and reducing emission. Therefore, CNPC fulfills those responsibilities as a substantial part of its overall strategy. Guided by low carbon and driven by innovation, petroleum corporations have taken constant innovation of low-carbon technologies, especially the development of green and low-carbon petroleum engineering technologies and equipment, as major measures for energy conservation and emission reduction. Large-scale development mode of unconventional resource anhydrous fracturing should be innovated. And supercritical CO₂ should be used to replace water for fracturing operation, in order to achieve multiple objectives of CO₂ burying, conserve water resource, improve single well production and ultimate recovery, realizing reduced emission and efficient utilization of CO₂ resources. Artificial lifting energy-saving and efficiency-increasing technologies and injection-production technology in the same well should also be innovated. Energy consumption of high water-cut wells is reduced to support the new low-carbon operation mode of high water-cut oilfields and realize energy saving and efficiency improvement during oil production by developing the operation efficiency of the lifting system and reducing the ineffective lifting of formation water. These technologies have been widely recognized by local and international experts and have greatly enhanced CNPC’s international influence. This study expounds the key technologies and equipment with regard to the development of green and low-carbon petroleum engineering and provide relevant suggestions.     

Green Road Construction Technologies in Guangzhou

Total road pavement in Guangzhou reaches 77 ×10⁶ m². Its huge maintenance and potential rehabilitation calls for a green road system. This paper presents a discussion, first about green road construction technologies together with their applications and development like reclaimed asphalt pavement, rubberized asphalt pavement, and warm mix asphalt; and then, about the key obstacles for promotion and activities, primarily for green road promotion, in the perspectives of the current technical and application situations in China and separately in Guangzhou. Based on environmental and conditional analysis, as well as a development expectation from an industrial viewpoint, this paper creates a development trend of green road technologies.     

低能大流强氢离子辐照对钨的刻蚀行为

在聚变相关的钨(W)偏滤器辐照下,研究了低能大流强氢(H)离子辐照对多晶钨材料的刻蚀行为。使用扫描电子显微镜(SEM)、导电原子力显微镜和基于SEM的电子背散射衍射等手段研究了大流强(~10²² ions/m²·s)、剂量为1.0×10²⁶ ions/m²、能量为5~200 eV的氢离子辐照对多晶W材料表面刻蚀行为的影响。结果表明,随着H离子辐照能量的增加W的溅射率迅速提高,W表面发生刻蚀后产生条纹状结构,而且同一晶粒上条纹的方向具有一致性,条纹两侧的缺陷分布明显不同,意味着W表面的刻蚀优先沿某一特定晶面方向进行。     

Multifilament Nb3Sn superconductors produced by the E.C.N. technique

Multifilament Nb3Sn conductors are produced by reduction of composites containing bundles of niobium tubes filled with NbSn2-powder and surrounded by pure copper. Heat treatment at temperatures between 575 and 675°C after final reduction causes the tin from the NbSn2-powder to diffuse into the niobium tubes, which results in a final Nb3Sn-layer at the inner side of the tube. Two types of experimental wire are produced, the first type consisting of 4 bundles of 9 tubular filaments, the powder cores having diameters of about 35 micron, the outer size of the wire being 1 mm square. The second type consists of 4 bundles of 45 tubular filaments. This type is fabricated in 3 sizes: round φ 2.3 and square 1.4 and 1.0 mm, corresponding with powder core diameters of 26,18 and 13 microns respectively. Critical current densities in the Nb3Sn-layers reach values of about 4 - 6 × 10⁹A/m²at 8 Tesla and 1,6 - 2,4 × 10⁹A/m²at 12 Tesla. Maximum critical temperatures are about 18.1 K with a ΔTcof 0.3 K.     

Approach for natural gas to be a primary energy source in China

This work reveals the positioning of natural gas in the evolution of world energy and the general law of its development. In the long-term adjustment of energy structure, natural gas has gradually become the primary energy source because of five factors: policy, resources, technology, facilities, and market. To expedite the revolution of energy production and consumption, China must urgently expand the use of natural gas toward a more positive role in complementing coal and renewable energy and prioritize its usage in three areas, namely, urban gas, power generation, and industrial fuel. Natural gas is expected to account for approximately 15% of China’s total energy consumption in the future. For natural gas to be the primary energy, the exploitation of gas resources must be expanded, resource access must be improved, a flexible trade system must be set up, infrastructure investment must be increased, and the security system must be enhanced.     

Effect of shape factor, operating stresses, and electricalconductors on the energy density of rotating machines

The ability to store as much energy as possible for the least weight, defined by the rotor's energy density (U/m~J/g), is of paramount importance to the pulsed power supply of electromagnetic guns. This paper extends the work presented in a complementary paper in which the shape factors, F_s, for a representative number of rotating machines were derived and compared. The effects of shape factor, maximum allowable operational stress σ_&thetas;max, and effective rotor density ρ_eff (determined by the addition of electrical conductors to the rotor for power extraction) on rotor energy density and tip speed are presented in this paper. A comparison between two candidate composite designs for electromagnetic pulsed power generation-a laminated disk (LD) and a rim rotor (RR)-is performed. Our analyses have determined that the true discriminator between the LD and the RR designs is the allowable stress each can operate at since they both have the same shape factor and about the same composite density. The LD design is limited by the interlaminar shear strength of the epoxy bond to hoop stresses in the range of 150 ksi(1.0·10⁹ N/m²), while the RR design is able to take full advantage of the strength limit of the composite fiber and operate at hoop stresses as high as 350 ksi (3.1·10⁹ N/m²)     

隔板工位送风末端气流组织数值模拟研究

工位送风通常与背景送风相结合来消除室内余热,该方式会增加系统的投资和运行费用。为解决此问题,采用数值模拟的方法对工位区迎面送风、面部双侧送风及头腿送风等末端形式的送风性能进行研究,试图用工位送风替代背景送风。研究结果表明,迎面送风和面部双侧送风在230m³/h~270m³/h风量范围内可替代背景送风,其中面部双侧送风消除工位区和背景区余热能力较强,在较小风量下就能达到室内温度要求;而头腿送风在144m³/h~288m³/h整个模拟风量范围内都不能替代背景送风。研究结果可为个性化环境设计提供参考。     

Measurement of weak magnetic fields using zero-field parametric resonance in optically pumped He4

A vector magnetometer has been built utilizing then = 0, p = 1parametric resonance associated with zero-field level crossings in the optically pumped 2³S1level of He⁴. The principles of operation are discussed and performance is described. The parametric resonance signal-to-noise ratio is 3.5 × 10⁴in a 0.5 Hz noise bandwidth. The linewidth is 9.7 × 10^-4G. Techniques for optimizing the sensitivity are discussed, and the sensitivity of the instrument is demonstrated by placing the sensor inside a superconducting magnetic shield and applying calibration signals, The peak-to-peak noise level is 1 × 10^-8G. The use of parametric resonance instruments to measure interplanetary and geomagnetic fields is discussed.     

Gas gain in xenon + 2,3 dimethyl-2-butene filled proportional counters

The gas gain in xenon-filled proportional counters can be greatly increased by the addition of a small quantity of 2,3 dimethyl-2-butene (DMB). We have found that a broad peak in gas gain appears when the concentration of additive is between 0.4% and 0.75% and the molecular number density of the gas filling is about 2.7 × 10²⁵ m⁻³ ( 1 atm). When the gas density is reduced to about 1.4 × 10²⁵ m⁻³ ( 0.5 atm) the peak becomes much sharper and better defined and reaches its maximum when the concentration of additive is 0.43%. Lowering the density to approximately 7.0 × 10²⁴ m⁻³ ( 0.26 atm) results in a very sharp, well defined peak centred on an additive concentration of 0.23%. The gas gains used to define these peaks were of the order of 10⁵, whilst in pure xenon at identical anode potentials the gas gain was of the order of 10.     

Developments in gas liquefaction and separation

Some of the most interesting papers presented to the Gas Liquefaction and Separation Commission of the IIR are reviewed. A novel LNG peak-load storage plant was described in which the excess cooling capacity available during most of the year is used to produce low cost liquid oxygen and nitrogen. On a larger scale, design studies were reported showing the advantages to be gained by cooling natural gas before admitting it to very long transmission pipelines. for duties above 100 x 10⁹ m³/year piping LNG is recommended.

The latest developments in large oxygen plants are surveyed, including the challenge of components designs. Alternative separation routes using absorption rather than distillation are reported. A novel cycle using dephlegemators and a compander for separating hydrocarbons is described.     

Magneto-optic insulators utilizing the optical activity of Co++(Td)

Large magneto-optic effects are associated with the crystal field transitions of Co++(Td) in a variety of spinel oxides. In the oxides, the F and P crystal field bands peak at about 1.5 and 0.6 μm, respectively. Many iron-containing quaternary compounds (CoTxFe2-xO4) have transition temperatures above ambient. Here, T is a trivalent metal ion such as Cr³⁺or Rh³⁺. Room-temperature magneto-optic measurements on a number of these compounds indicate peak Faraday effects in the range of 0.5 × 10⁵to 1.0 × 10⁵(deg/cm) at about 0.6 μm. The Curie temperature may be adjusted by the compositional parameter x and normal remanence of the surface Kerr effects are observed. The latter properties are potentially useful for optical memory devices. These materials are considered for isolation and modulation devices in the 5.0 to 12.0 μm wavelength range.     

Surface-micromachined pyroelectric infrared imaging array withvertically integrated signal processing circuitry

Surface-micromachining techniques have been used in the fabrication of a 64×64 element PbTiO₃ pyroelectric infrared imager. Polysilicon microbridges of 1.2 μm-thickness have been formed 0.8 μm above the surface of a silicon wafer. Each of the 4096 polysilicon microbridges measures 50×50 μm² and forms a low thermal mass support for a 30×30 μm² PbTiO₃ pyroelectric capacitor with a thickness of 0.36 μm. The air-bridge formed reduces the thermal conduction path between the detector element and substrate. An NMOS preamplifier cell is located directly beneath each microbridge element. The measured blackbody voltage responsivity at 30 Hz is 1.2×10⁴ V/W. The corresponding measured normalized detectivity (unamplified) D* is 2×10⁸ cm-Hz^1/2W at 30 Hz. The test chip fabricated measures 1×1 cm² and contains more than ten thousand transistors and 4096 micromechanical structures with integrated ferroelectric microsensors. The technique of stacking of microsensors and integrated circuits represents a new approach for achieving high-density and high-performance integrated pyroelectric microsensors through minimization of circuit to sensor interconnection with extremely small thermal crosstalk     

Field-lowering carrier excitation in cadmium arsenide thin films

Cadmium arsenide is a II–V semiconductor which exhibits n-type intrinsic conductivity with high mobility up to μ_n=1.0–1.5 m²/V s. Potential applications include magnetoresistors and both thermal and photodetectors, which require electrical characterization over a wide range of deposition and measurement conditions. The films were prepared by vacuum evaporation with deposition rates in the range 0.5–6.0 nm/s and substrate temperatures maintained at constant values of 20–120°C. Sandwich-type samples were deposited with film thicknesses of 0.1–1.1 μm using evaporated electrodes of Ag and occasionally Au or Al. Above a typical electric field F_b of up to 5×10⁷ V/m all samples showed instabilities characteristic of dielectric breakdown or electroforming. Below this field they showed a high-field conduction process with logJ∝V^1/2, where J is the current density and V the applied voltage. This type of dependence is indicative of carrier excitation over a potential barrier whose effective barrier height has been lowered by the high electric field. The field-lowering coefficient β had a value of (1.2–5.3)×10⁻⁵ eV m^1/2/V^1/2 which is reasonably consistent with the theoretical value of β_PF=2.19×10⁻⁵ eV m^1/2/V^1/2 expected when the field-lowering occurs at donor-like centres in the semiconductor (Poole–Frenkel effect). For thinner films Schottky emission was more probable. The effects of the film thickness, electrode materials, deposition rate, and substrate temperature on the conductivity behaviour are discussed.     

Effect of Y codoping on luminescence decays of the I level in Er-doped AlO powders prepared by a sol-gel method

The luminescence lifetime of the 0.01 mol.%–0.1 mol.% Er³⁺- and 0–20 mol.% Y³⁺-codoped Al₂O₃ powders prepared at a sintering temperature of 900°C in a non-aqueous sol-gel method has been investigated to explore the enhanced mechanism of photoluminescence properties of the Er³⁺-doped Al₂O₃ by Y³⁺ codoping. For the 0.1 mol.% Er³⁺–Y³⁺-codoped Al₂O₃ powders, the measured lifetime of Er³⁺ gradually increases with increasing Y³⁺ concentration. Consequently, codoping with 20 mol.% Y³⁺ leads to an increase in the measured lifetime from 3.5 to 5.8 ms. By comparing the measured lifetime for different Er³⁺ concentrations in the Al₂O₃ powders, the radiative lifetime of both the Er³⁺-doped and the Er³⁺–Y³⁺-codoped Al₂O₃ powders is estimated to be about 7.5 ms. Infrared absorption spectra indicate that Y³⁺ codoping does not change the –OH content in the Er³⁺–Y³⁺-codoped Al₂O₃ powders. The prolonged luminescence lifetime of the ⁴I_13/2 level of Er³⁺ in Er³⁺-doped Al₂O₃ powders by Y³⁺ codoping is ascribed to the decrease in the energy transfer rate between the Er³⁺ ions and the Er³⁺ and –OH, respectively, due to the suppressed interaction between Er³⁺ ions.