Power Pinch Analysis supply side management: strategy on purchasing and selling of electricity

Pinch analysis concept has been recently stepped into the realm of design and optimisation of power systems. One well-established pinch analysis that has been used in power systems design and optimisation is called Power Pinch Analysis (PoPA). In PoPA, both graphical and numerical approaches have provided an insight on the systematic approach to target and design various power systems. By only visualising the minimum amount of outsource energy required by the power system, the graphical PoPA method as a whole does not show the purchasing of outsource energy based on the exact time intervals. Using graphical PoPA, the objective of this study is to determine a proper strategy to buy and sell outsource electricity to improve the overall performance of a hybrid power system comprising renewable power generators and energy storage system. The strategies are made based on three design parameters: energy-related capacity, power-related capacity of energy storage and maximum grid power rating between centralised grid and hybrid power system. While deciding on the best strategy and heuristics to be implemented, the effects on system operation and economy are indirectly analysed. It is experimented that the output can benefit electricity consumers or producers.     

Integration of new processes and geothermal heat into a wood processing cluster

In this study, process integration methods have been used to investigate the heat integration of new processes with a model wood processing cluster. Due to anticipated future demand for bio-derived fuels and chemicals, it is important to identify which emerging conversion processes would benefit from integration with existing facilities. Identifying specific integration schemes help quantify economic and environmental benefits and can assist the commercialisation and adoption of these new processes. The synergies gained through integration are examples of industrial symbiosis, which is the sharing of resources between co-located facilities. A background/foreground analysis of the grand composite curves was used to determine any heat recovery potential between the cluster and the new entrant and the effect on the utility system. The model cluster consisted of a thermo-mechanical pulp and paper mill, kraft pulp and paper mill and saw mill. Some of the processes had little or no integration potential due to having similar pinch temperatures as the cluster. Processes based on biomass gasification had large potential due to the pinch temperatures being very different and the shape of grand composite curve being complimentary. The integration of geothermal energy for process heat was also investigated and if available has a distinct advantage of allowing surplus black liquor to be used as a feedstock to some of the new processes. Results show that high pinch temperature processes show the greatest integration potential and can provide significant fuel reduction potential.     

滚动轴承支承的齿轮传动轴-板耦合结构功率流传递特性研究

针对影响机械设备整机工作性能的齿轮箱系统动态特性,通过对齿轮箱系统振动噪声的产生机理及传递路径分析,建立轴系传动系统中典型组合结构—板-滚动轴承-齿轮轴-滚动轴承-板耦合系统的动力学模型,并应用子结构导纳法推导计算通过滚动轴承传递到箱板振动功率流的模态解。考虑到模态解的模态密集性,据统计能量分析原理,研究齿轮轴-滚动轴承-板耦合结构的耦合损耗因子的估算方法,统计能量分析与模态解的结果显示,吻合性较好。对振动能量通过滚动轴承传递的特性及影响因素进行研究分析,为齿轮箱系统减振降噪设计提供理论依据。     

Energy sector planning using multiple-index pinch analysis

Pinch analysis was initially developed as a methodology for optimizing energy efficiency in process plants. Applications of pinch analysis applications are based on common principles of using stream quantity and quality to determine optimal system targets. This initial targeting step identifies the pinch point, which then allows complex problems to be decomposed for the subsequent design of an optimal network using insights drawn from the targeting stage. One important class of pinch analysis problems is energy planning with footprint constraints, which began with the development of carbon emissions pinch analysis; in such problems, energy sources and demands are characterized by carbon footprint as the quality index. This methodology has been extended by using alternative quality indexes that measure different sustainability dimensions, such as water footprint, land footprint, emergy transformity, inoperability risk, energy return on investment and human fatalities. Pinch analysis variants still have the limitation of being able to use one quality index at a time, while previous attempts to develop pinch analysis methods using multiple indices have only been partially successful for special cases. In this work, a multiple-index pinch analysis method is developed by using an aggregate quality index, based on a weighted linear function of different quality indexes normally used in energy planning. The weights used to compute the aggregate index are determined via the analytic hierarchy process. A case study for Indian power sector is solved to illustrate how this approach allows multiple sustainability dimensions to be accounted for in energy planning.     

复合材料层压板抗冲击行为及表征方法的实验研究

对14种复合材料体系约800个试样进行了冲击阻抗和含损伤层压板压缩强度试验研究,研究发现对于同一种复合材料层压板的冲击能量-凹坑深度曲线和凹坑深度-压缩破坏应变曲线均存在拐点,在出现拐点后内部的分层损伤叠加面积基本不再增加,压缩剩余强度基本不再降低,表面冲击部位开始出现纤维断裂。研究表明,采用传统CAI来表征损伤容限性能的方法可能得到与实际结构损伤容限特性相反的结论。因此,提出了利用拐点附近特性来表征复合材料层压板的抗冲击行为（包括损伤阻抗和损伤容限）的建议,即分别采用QSI方法得到的准各向同性层压板的最大接触力F_max和压缩破坏强度（应变）的门槛值CAIT来表征复合材料层压板的损伤阻抗和损伤容限行为。      

北京某教学楼空气源热泵供暖系统现场实验

本文在2016—2017年供暖季,对北京某教学楼A、B两区域的空气源热泵地板供暖系统进行了现场实验,其中A区系统安装了室温控制和水力平衡装置,系统运行方式分为出水温度为35℃正常供暖的阶段1和20℃寒假防冻保护的阶段2。通过对室内外温度、系统供回水温度及流量和耗电量长达67 d的监测,对比分析了两系统在寒冷地区的运行效果。实验结果表明:阶段1期间,A区不但能够保证室内房间温度更适宜,供热量也明显低于B区,耗电量实现24.4%的节能效果。此外,控制装置不会影响A区机组性能,A、B区的COP分别达到3.56和3.54,并且机组实际的运行性能与性能曲线接近。而阶段2期间,温控器设置未更改,A区节能率略有下降,达到16.3%,建议温控器匹配机组出水温度进行设置实现进一步的节能效果。     

压电复合材料中幂函数型曲线裂纹的反平面问题

通过构造新保角映射, 利用Stroh公式研究了远场受反平面剪应力和面内电载荷共同作用下无限大压电复合材料中幂函数型曲线裂纹的断裂行为。给出了电不可渗透边界条件下裂纹尖端场强度因子和机械应变能释放率的解析解。该解析解在幂函数的幂次为零时, 可退化为已有文献中无限大压电复合材料含直线裂纹的结果, 证明了其合理性。由解析解可知, 裂纹几何形状一定时, 电场分布将不受机械载荷的影响。最后, 通过数值算例讨论了幂函数的幂次、 系数及其在 x₁轴上的投影长度对机械应变能释放率的影响。结果表明, 当压电体仅受 x₂方向载荷作用时, 对于给定幂次与开口的曲线裂纹, 在 x₁轴上的投影长度存在一临界值使其最容易开裂; 而对于给定投影长度与幂次的曲线裂纹, 开口越大裂纹越容易扩展。      

Power system energy analysis incorporating comprehensive load characteristics

The energy function method developed so far assumes that the active load is constant. However, most of the actual load is voltage dependent, which hinders the application of the energy analysis method to the actual power system. On the other hand, the fast development of measurement techniques, especially the wide area measurement systems (WAMS) applied widely in worldwide power system nowadays, presses for the on-line transient stability analysis tools based on the system measurements. The voltage-dependent load into the energy analysis of power system transient stability is discussed. The effect of the comprehensive load characteristics on the system energy is discussed and a WAMS-based energy indicator on the system stability status is proposed. The indicator is easy to be calculated and thus real-time in the operation centre is monitored. The proposed method does not rely on any specific load model, and various load characteristics on different buses can be considered. Simulations on two test systems verify the effectiveness of the proposed method.     

On the response sensitivity of an optimally designed functionally graded layer

Sensitivity of the response of an optimally designed functionally graded (FG) thermomechanical system is investigated. The system is a transversely isotropic layer subjected to a thermal gradient. The layer is modeled as a biconstituent composite with a microstructure characterized by the design parameters: fiber volume fraction, shape, and orientation. Performance is quantified by a linear combination of the layer's curvature and strain energy density. Of particular interest is the comparison of variability of response to variations in the design parameters versus variability in such things as constituent material properties, and fiber misalignment. These are issues of significance for the manufacturing of functionally graded materials (FGMs). It is concluded that while not all FG systems show a significant sensitivity to texture (i.e. fiber shape and orientation) there do exist some systems for which response is markedly affected by texture even in comparison to significant variabilities in constituent material properties and fiber misalignment.     

Combined design and load shifting for distributed energy system

Renewable distributed energy generation (DEG) system plays an important role in future power developments and is one of the options to reduce energy consumption. It is envisaged that energy efficiency of DEG systems can be improved via load shifting (LS). This study proposed a heuristic-based numerical approach to perform LS analysis on renewable stand-alone DEG systems. The technique is an extension from a method known as the Electric System Cascade Analysis (ESCA). The new technique, which focuses on efficient electricity utilisation is able to determine the optimal: (i) load profiles, (ii) capacity of power generator, (iii) capacity and power of energy storage (ES) and (iv) charging/discharging schedule of ES. The stage-wise technique allows user to compare and determine the optimal design in a flexible way while having a better understanding of the selection of options. The application of ESCA-LS on a case study revealed that after incorporation of direct LS (load manipulation) in addition to LS by ES (supply manipulation), the power generators and ES capacity can be further reduced. While reduction of 3.1 % for solar-PV installation area and 3.9 % for biomass power generator is recorded, ES power-related capacity and energy-related capacity managed a higher reduction of up to 19.0 and 13.2 % for the main case study     

缝线增强层合板混合模式弯曲试验的数值模拟

对缝线在复合材料层合板中的桥联作用进行参数分析,结果显示缝线的直径和拉伸强度,缝合角度,层合板厚度和挤压强度均会对缝线的桥联曲线以及断裂能产生影响,甚至改变缝线的破坏模式。以计算所得的桥联曲线作为输入参数,分别用连接器(Connector)和离散内聚力单元(Cohesive单元)的方法建立有限元模型,模拟缝线增强复合材料层合板的混合模式弯曲(MMB,Mix-Mode Bending)试验。两种方法的有限元计算结果具有较好的一致性,且均能够与文献中的试验数据较好吻合。相比离散Cohesive单元模型,Connector模型的计算效率更高,需要的输入参数更少,且建模更为简便。     

Optimal design and integration of solar systems and fossil fuels for sustainable and stable power outlet

Widespread industrial utilization of solar energy is an important goal that requires overcoming several technical challenges. One of the key hurdles is the need to address the temporal fluctuations in incident solar power (e.g., on an hourly basis or seasonally) which lead to variations in the outlet power. This work is aimed at the development of a systematic design procedure providing a stable power outlet while using solar systems. First, the dynamic performance of solar collectors is parametrically modeled. Next, an optimization formulation is developed as the basis for the design procedure which accounts for the integration of solar and fossil energy sources in a power system. The procedure determines the optimal mix of energy forms (solar vs. fossil) to be supplied to the process, the system specifications, and the dynamic operation of the system. The developed procedure includes gathering and generation of relevant solar and climatic data, modeling of the various components of the solar, fossil, and power generation systems, and optimization of several aspects of the hybrid system. A case study is solved to demonstrate the effectiveness and applicability of the devised procedure.     

Morphology and degradation properties of PCL/HYAFF11® composite scaffolds with multi-scale degradation rate

The analysis of scaffold degradation is a promising strategy for understanding the dynamic changes in texture and pore morphology which accompany polymer resorption, and for collecting same fundamental indicators regarding the potential fate of the scaffold in the biological environment. In this study, we investigate the morphology and degradation properties of three composite scaffolds based on poly(ε-caprolactone) (PCL) embedded with benzyl ester of hyaluronic acid (HYAFF11®) phases, and, in turn, different reinforcement systems – i.e., calcium phosphate particles or continuous poly(lactic acid) (PLA) fibres. Scanning electron microscopy (SEM) and μ-tomography supported by digital image analysis enabled a not invasive investigation of the scaffold morphology, providing a quantitative assessment of porosity (which ranged from 63.1 to 82.8), pore sizes (which varied from 170.5 to 230.4 μm) and pore interconnectivity. Thermal analyses (DSC and TGA) and Raman spectroscopy demonstrated the multi-scale degradation of the composite with highly tailoring degradation kinetics depending on the component material phases and scaffold architecture changes, due to their conditioning in simulated in vivo environment (i.e., SBF solution). These results demonstrate that the judicious mixing of materials with faster (i.e., HYAFF11) and slower (i.e., PLA and PCL) degradation kinetics, different size and shape (i.e., domains, particles or long fibres), certainly concurs to design a smart composite scaffold with time-controlled degradation which can support the regeneration of a large variety of tissues, from the cartilage to the bone.     

樟脑磺酸掺杂聚苯胺复合阳极在海底微生物燃料电池中的应用

制备了一种樟脑磺酸掺杂聚苯胺(PANI-(D-CSA))新型复合阳极,研究了其最佳配比,并在海底微生物燃料电池(BMFC)中测定其电化学性能.采用XRD衍射、热失重对聚苯胺阳极材料进行了表征.结构分析表明,PANI-(D-CSA)为部分结晶,热稳定性较好.性能测试表明,PANI-(D-CSA)质量分数为50%时复合阳极...     

Empirical efficiency and volume relationships for HPGe detectors

We have extended the empirical work of Vano et al.[1] relating the slope of the detector efficiency curve to the active volume for Ge detectors. The analysis was carried out using Monte Carlo techniques and covered a wide range of incident energies (200 keV-20 MeV) and active volumes (19.6 cm³–396 cm³). It is shown that the expression of Vano et al.[1] is only valid over the energy range 200 keV-3 MeV for active volumes <50 cm³. The upper bound decreases to 2 MeV for volumes of a few hundred cm³. The usable energy range can, however, be extended to 6 MeV by introducing higher order terms into the polynomial. Above this energy, the shape of the efficiency curve is better described by a non-linear function since linear forms fail simultaneously to fit large active volumes and high energies. We therefore propose a composite function which reduces to the form given in Vano et al. in the low energy/active volume limit. By comparison with the Monte Carlo results, it is estimated that relative efficiencies can be calculated to within 6% over the energy range 200 keV-20 MeV and active volumes 20 cm³–400 cm³. Since the largest errors occur for the smallest volumes, we recommend that for energies <3 MeV a two-fold approach be followed, i.e. using the expression of Vano et al.[1] for active volumes less than 50 cm³ and the proposed non-linear form for larger volumes. For high energy work (E > 3 MeV), we advocate the non-linear form. In this way, average errors can be kept 3%. Finally, we point out that the real power of the expression of Vano et al. lies not in predicting efficiencies, but active volumes.     

Zero-Power Magnetic Levitation Using Composite of Magnetostrictive/Piezoelectric Materials

We present a zero-power magnetic levitation technique using a composite of magnetostrictive and piezoelectric materials. The composite is bonded to iron yokes with an attached permanent magnet, by which the magnetic force exerted on movable yoke via air gap is controlled by the applied voltage on the piezoelectric material. The magnetic force control is based on the inverse magnetostrictive effect of the magnetostrictive material, i.e., the magnetization is varied with mechanical stress. The advantage of the composite is zero power consumption, because no current flows in static operation as a result of the capacitive property of the piezoelectric material. This feature will be useful in high-precision stage or conveyor systems using magnetic levitation where heat generation and power consumption should be avoided. The zero power characteristic of the composite is valid at any reference gap or load, whereas that of the conventional electromagnetic type is valid only at the equilibrium gap. We performed two levitation experiments: one using the composite to demonstrate the zero power advantage, and the other combining the composite to adjust the bias gap and electromagnet to stabilize the motion of the levitated yoke. The composite driven by a small dc-dc converter successfully varied the gap and maintained it constant with zero power consumption.     

Preliminary Study on Evaluation System of Capability of Composites to Withstand Impact

Inthemiddleof1970th,itwasfoundthatthe mainweaknessofcompositelaminateswastheirsen sitivitytoimpactanditlimitedextensiveuseofcom positesinaircraftstructures.Usuallyitwascon sid eredthatthesensibilitycamefrombrittlenessofresin matrix.Thereforedevelopmentoftoughenedresin matrixhasbeenpaidthemostattentiontobymateri alscientistsforthelast30years.Inordertoevaluate thetoughenedresinmatrixcompositesteststand ards[1,2]bythecharacteristicquantityofCAI(Com pressionAfterImpact)wasproposedin1980th.In th…     

Quasi-static penetration resistance behavior of glass fiber reinforced thermoplastic composites

Quasi-static penetration resistance of a composite structure represents the energy dissipating capacity of the structure under transverse loading without dynamic and rate effects. In this paper, a comparative study of the quasi-static penetration resistance behavior of S-2 Glass/SC-15, S-2 Glass/HDPE and E-Glass/HDPE composite systems with varying thicknesses, i.e., 1.4–8.4-mm, is presented using the Quasi-Static Punch Shear Test (QS-PST) methodology developed earlier. The penetration resistance behavior is usually presented by a series of force–displacement graphs at different support conditions, the integral of which is the energy dissipated by the composite during the quasi-static penetration at corresponding support conditions. The penetration energy varies with the diameter of the support span which is usually higher than the punch diameter, and also with the thickness of the composite laminate. During QS-PST experiments, a flat punch of diameter 7.6-mm with a range of support spans 8.89–50.8-mm has been used to obtain varying support span to punch diameter ratios (i.e., SPR = D_S/D_P = 1.16, 1.33, 1.67, 2.00, 2.33, 2.67, etc.). In order to compare the penetration resistance behavior of three different material systems, the S-2 Glass/SC-15, S-2 Glass/HDPE and E-Glass/HDPE composites of identical layer counts are used and the S-2 Glass/SC15 composite system is considered as the baseline. Composite plate specimens are sectioned after the test and then dipped into an ink–alcohol solution to study the damage mechanisms at different SPRs. Non-linear penetration stiffness and an average penetration resistance force are defined to quantify the average penetration resistance of each material. S-2 Glass and E-Glass reinforced HDPE composite material showed lower stiffness, lower peak force, higher deflection, lower damage area, and lower energy dissipation as compared to the baseline. A detailed comparison of results is presented.     

Optimized support systems for spaceborne dewars

In a long-lifetime dewar, heat loads to the cryogen fall into two distinct categories: parasitic heat leak (i.e. conduction and radiation from the vacuum shell) and internal heat loads (i.e. electrical power dissipation and telescope aperture heating in the case of cooled telescope systems). To accommodate launch loads, the cryogen tank support system of a spaceborne dewar must be stout, and heat conducted from the vacuum shell through the supports can have a large influence on cryogen loss rate. Sophisticated support systems using low conductivity composite materials for thermal optimization have consequently been developed. The most thermally efficient support system used to date in flight hardware is fibreglass/epoxy tension straps. To provide even better thermal efficiency than straps, various attempts have been made over the last two decades to develop dual support concepts in which a primary support reacts launch loads and a smaller, more thermally efficient support then holds the cold assembly in place after launch. This Paper compares predicted dewar performance for several cases using both tension straps and the best developed dual support approach, passive orbital disconnect struts (PODS). Results show that cryogen loss rates are very similar for both systems. Straps provide a slight advantage for storage of lighter cryogens such as helium and hydrogen, and PODS are slightly better for heavier cryogens such as nitrogen and oxygen. The PODS system is more complex than straps, and a flightworthy design does not yet exist. The performance of a flight system using straps is at this time more predictable than one using PODS.