Intelligent thermal energy meter cum controller for solar water heating systems

A microcontroller based, thermal energy meter cum controller (TEMC) suitable for solar thermal systems has been developed. It monitors solar radiation, ambient temperature, fluid flow rate, and temperature of fluid at various locations of the system and computes the energy transfer rate. It also controls the operation of the fluid-circulating pump depending on the temperature difference across the solar collector field. The accuracy of energy measurement is +/-1.5%. The instrument has been tested in a solar water heating system. Its operation became automatic with savings in electrical energy consumption of pump by 30% on cloudy days.

Photo-​induced proton coupled electron transfer from a benzophenone 'antenna' to an isoindoline nitroxide

The current study reports the synthesis and properties of a novel isoindoline nitroxide contg. a benzophenone chromophore fused into the carbon framework. When exposed to UV light, rather than undergoing traditional benzophenone photochem. pathways, the presence of the nitroxide enables an energy transfer process whereby the nitroxide enters an excited state which induces an efficient hydrogen atom transfer from unactivated alkanes.

Mode of inhibition of mitochondrial energy transduction by chlorophenoxyisobutyrate

1. a-p-Chlorophenoxyisobutyric acid, the ethyl ester of which is widely used as an antihypercholesterolaemic drug, is an inhibitor of energy-transfer reactions in isolated rat liver mitochondria. 2. The compound at lower concentrations (<4.0mmol/mg of mitochondrial protein) inhibits state 3 oxidation, stimulates state 4 oxidation, abolishes respiratory control and stimulates the latent adenosine triphosphatase activity of mitochondria. The inhibition imposed on state 3 oxidation is relieved by dinitrophenol. 3. At higher concentrations it inhibits coupled phosphorylation as well as dinitrophenol-stimulated adenosine triphosphatase activity. The inhibition of state 3 oxidation under these conditions is not reversed by uncouplers. 4. The three coupling sites of phosphorylation exhibit differential susceptibility to inactivation by this compound. Coupled phosphorylation at the first site is abolished at a drug concentration of 3.0mmol/mg of protein. The third site is inactivated when the concentration of the drug reaches 5.0mmol/mg of protein. The second site is the most refractory and drug concentrations of the order of 10.0mmol/mg of protein are required effectively to inhibit phosphorylation at this site. 5. The compound also inhibits ATP-dependent reversal of electron transport as well as the adenosine triphosphatase activity in submitochondrial particles. 6. The oxidation of NADH and succinate in these particles is not inhibited. 7. These properties indicate that the compound acts as an `inhibitory uncoupler' of energy-transfer reactions in isolated mitochondria.

Embodied energy of service trading in Hong Kong

Purpose Energy is a resource of strategic importance for high density cities. International trade reshapes the urban economy and industrial structure of a city, which will indirectly affect energy use. As an international trade hub, Hong Kong relies on the import and export of services. Energy performance in the international trading of these services needs to be properly understood and assessed for Hong Kong’s urban renewal efforts. Design/methodology/approach This study evaluates Hong Kong’s embodied energy in service trades based on an input-output analysis. The three criteria used for assessment include trading areas, industry sector, and trade balance. Findings Analyzed by region, results show that Mainland China and the USA are the two largest sources of embodied energy in imports of services, while Mainland China and Japan are the two largest destinations of exports. In terms of net embodied energy transfer, Hong Kong mainly receives net energy import from Mainland China and the USA and supplies net energy export to Japan, the UK and Taiwan. Among industry sectors, Manufacturing services, Transport and Travel contribute most significantly to the embodied energy in Hong Kong’s imported services, while Transport and Travel contribute most to the energy embodied in exported services. Originality/value This study identifies the characteristics of energy consumption of service trading and establishes a feasible approach to analyze energy performance of service trade in energy-deficient Hong Kong for the first time. It provides necessary understanding and foundation for developing energy strategies in a service-based, high density urban economy.

Photophysics of conjugated polymers: interplay between Forster energy migration and defect concentration in shaping a photochemical funnel in PPV

Recent single molecule experiments have suggested the existence of a photochemical funnel in the photophysics of conjugated polymers, like poly[2-methoxy-5-(2'-ethylhexyl)oxy-1,4-phenylenevinylene] (MEH-PPV). The funnel is believed to be a consequence of the presence of conformational or chemical defects along the polymer chain and efficient non-radiative energy transfer among different chromophore segments. Here we address the effect of the excitation energy dynamics on the photophysics of PPV. The PPV chain is modeled as a polymer with the length distribution of chromophores given either by a Gaussian or by a Poisson distribution. We observe that the Poisson distribution of the segment lengths explains the photophysics of PPV better than the Gaussian distribution. A recently proposed version of an extended particle-in-a-box' model is used to calculate the exciton energies and the transition dipole moments of the chromophores, and a master equation to describe the excitation energy transfer among different chromophores. The rate of energy transfer is assumed to be given here, as a first approximation, by the well-known Forster expression. The observed excitation population dynamics confirms the photochemical funneling of excitation energy from shorter to longer chromophores of the polymer chain. The time scale of spectral shift and energy transfer for our model polymer, with realistic values of optical parameters, is in the range of 200-300 ps. We find that the excitation energy may not always migrate towards the longest chromophore segments in the polymer chain as the efficiency of energy transfer between chromophores depends on the separation distance between the two and their relative orientation.

Optimization and design of energy transport system for solar cooking application

This paper proposes a hybrid solar cooking system where the solar energy is transported to the kitchen. The thermal energy source is used to supplement the Liquefied Petroleum Gas (LPG) that is in common use in kitchens. Solar energy is transferred to the kitchen by means of a circulating fluid. Energy collected from sun is maximized by changing the flow rate dynamically. This paper proposes a concept of maximum power point tracking (MPPT) for the solar thermal collector. The diameter of the pipe is selected to optimize the overall energy transfer. Design and sizing of different components of the system are explained. Concept of MPPT is validated with simulation and experimental results. (C) 2010 Elsevier Ltd. All rights reserved.

Photoluminescence of Sr(2-x)Ln(x)CeO(4+x/2) (Ln = Eu, Sm or Yb) prepared by a wet chemical method

A wet chemical route is developed for the preparation of Sr2CeO4 denoted the carbonate-gel composite technique. This involves the coprecipitation of strontium as fine particles of carbonates within hydrated gels of ceria (CeO2.xH(2)O, 40transfer (CT) transition resulting from the interaction of Ce4+ ion with the neighboring oxide ions. The effect of next-nearest-neighbor (NNN) environment on the Ce4+-O2- CT emission is studied by doping with Eu3+, Sm3+ or Yb3+ which in turn, have unique charge-transfer associated energy levels in the excited states in oxides. Efficient energy transfer occurs from Ce4+-O2- CT state to trivalent lanthanide ions (Ln(3+)) if the latter has CT excited states, leading to sensitizer-activator relation, through non-resonance process involving exchange interaction. Yb3+-substituted Sr2CeO4 does not show any line emission because the energy of Yb3+-O2- CT level is higher than that of the Ce4+-O2- CT level. Sr2-xEuxCeO4+x/2 shows white emission at xless than or equal to0.02 because of the dominant intensities of D-5(2)-F-7(0-3) transitions in blue-green region whereas the intensities of D-5(0)-F-7(0-3) transitions in orange-red regions dominate at concentrations xgreater than or equal to0.03 and give red emission. The appearance of all the emissions from D-5(2), D-5(1) and D-5(0) excited states to the F-7(0-3) ground multiplets of Eu3+ is explained on the basis of the shift from the hypersensitive electric-dipole to magnetic-dipole related transitions with the variation in site symmetry with increasing concentration of Eu3+. White emission of Sr2-x SmxCeO4+x/2 at xless than or equal to0.02 is due the co-existence of Ce4+-O2- CT emission and (4)G(4)(5/2)-H-6(J) Sm3+ transitions whereas only the Sm3+ red emission prevails for xgreater than or equal to0.03. The above unique changes in PL emission features are explained in terms of the changes in NNN environments of Ce4+. Quenching of Ce4+-O2- CT emission by other Ln(3+) is due to the ground state crossover arising out of the NNN interactions.

Basic equations for suspension flows with interphase mass-transfer

In the case of suspension flows, the rate of interphase momentum transfer M(k) and that of interphase energy transfer E(k), which were expressed as a sum of infinite discontinuities by Ishii, have been reduced to the sum of several terms which have concise physical significance. M(k) is composed of the following terms: (i) the momentum carried by the interphase mass transfer; (ii) the interphase drag force due to the relative motion between phases; (iii) the interphase force produced by the concentration gradient of the dispersed phase in a pressure field. And E(k) is composed of the following four terms, that is, the energy carried by the interphase mass transfer, the work produced by the interphase forces of the second and third parts above, and the heat transfer between phases. It is concluded from the results that (i) the term, (-alpha-k-nabla-p), which is related to the pressure gradient in the momentum equation, can be derived from the basic conservation laws without introducing the "shared-pressure presumption"; (ii) the mean velocity of the action point of the interphase drag is the mean velocity of the interface displacement, upsilonBAR-i. It is approximately equal to the mean velocity of the dispersed phase, upsilonBAR-d. Hence the work terms produced by the drag forces are f(dc) . upsilonBAR-d, and f(cd) . upsilonBAR-d, respectively, with upsilonBAR-i not being replaced by the mean velocity of the continuous phase, upsilonBAR-c; (iii) by analogy, the terms of the momentum transfer due to phase change are upsilonBAR-d-GAMMA-c, and upsilonBAR-d-GAMMA-d, respectively; (iv) since the transformation between explicit heat and latent heat occurs in the process of phase change, the algebraic sum of the heat transfer between phases is not equal to zero. Q(ic) and Q(id) are composed of the explicit heat and latent heat, so that the sum Q(ic) + Q(id)) is equal to zero.

Mass Energy and Flow in closed ecosystems

The general equations of biomass and energy transfer for an n-species, closed ecosystem are written. It is demonstrated how in "ecological time" the parameters describing the dynamics of biomass transfer are related to the parameters of energy transfer, such as respiration, fixation, and energy content. This relationship is determinate for the straight-chain ecosystem, and a simple example is worked out. The results show how the density dependent terms in population dynamics arise naturally, and how the stable system exhibits a hierarchy in energy per unit biomass. A procedure is proposed for extending the theory to include webbed systems, and the particular difficulties involved in the extension are brought before the scientific community for discussion.

Photoluminescence of Ag nanoparticle embedded Tb3+/Ce3+ codoped NaYF4/PVP nanofibers prepared by electrospinning

Ag nanoparticle embedded NaYF4:0.05Tb center dot chi Ce/ PVP (PVP stands for poly(vinyl pyrrolidone)) composite nanofibers have been prepared by electrospinning. A field emission scanning electron microscope and x-ray diffraction have been utilized to characterize the size, morphology and structure of the as-prepared electrospun nanofibers. Obvious photoluminescence (PL) of NaYF4:0.05Tb center dot 0.05Ce/PVP electrospun nanofibers due to the efficient energy transfer from Ce3+ to Tb3+ ions is observed. The PL intensity of the electrospun nanofibers decreases gradually with the addition of Ag nanoparticles. No obvious surface plasmon resonance enhanced luminescence is observed. The reasons for the weakening of the emission intensity with the addition of Ag nanoparticles have also been discussed in this work.

A study of a new electromechanical energy conversion process using superconducting frequency modulated resonators

Experimental demonstrations and theoretical analyses of a new electromechanical energy conversion process which is made feasible only by the unique properties of superconductors are presented in this dissertation. This energy conversion process is characterized by a highly efficient direct energy transformation from microwave energy into mechanical energy or vice versa and can be achieved at high power level. It is an application of a well established physical principle known as the adiabatic theorem (Boltzmann-Ehrenfest theorem) and in this case time dependent superconducting boundaries provide the necessary interface between the microwave energy on one hand and the mechanical work on the other. The mechanism which brings about the conversion is another known phenomenon - the Doppler effect. The resonant frequency of a superconducting resonator undergoes continuous infinitesimal shifts when the resonator boundaries are adiabatically changed in time by an external mechanical mechanism. These small frequency shifts can accumulate coherently over an extended period of time to produce a macroscopic shift when the resonator remains resonantly excited throughout this process. In addition, the electromagnetic energy in s ide the resonator which is proportional to the oscillation frequency is al so accordingly changed so that a direct conversion between electromagnetic and mechanical energies takes place. The intrinsically high efficiency of this process is due to the electromechanical interactions involved in the conversion rather than a process of thermodynamic nature and therefore is not limited by the thermodynamic value.

A highly reentrant superconducting resonator resonating in the range of 90 to 160 MHz was used for demonstrating this new conversion technique. The resonant frequency was mechanically modulated at a rate of two kilohertz. Experimental results showed that the time evolution of the electromagnetic energy inside this frequency modulated (FM) superconducting resonator indeed behaved as predicted and thus demonstrated the unique features of this process. A proposed usage of FM superconducting resonators as electromechanical energy conversion devices is given along with some practical design considerations. This device seems to be very promising in producing high power (~10W/cm^3) microwave energy at 10 - 30 GHz.

Weakly coupled FM resonator system is also analytically studied for its potential applications. This system shows an interesting switching characteristic with which the spatial distribution of microwave energies can be manipulated by external means. It was found that if the modulation was properly applied, a high degree (>95%) of unidirectional energy transfer from one resonator to the other could be accomplished. Applications of this characteristic to fabricate high efficiency energy switching devices and high power microwave pulse generators are also found feasible with present superconducting technology.

O pré-aquecimento do universo: da ressonância paramétrica à turbulência

A inflação consegue dar conta de uma série de problemas do Modelo padrão da Cosmologia, preservando ainda o sucesso do modelo do Big Bang. Na sua versão mais simples, a inflação é controlada por um campo escalar, o ínflaton, que faz com que o universo se expanda exponencialmente. Após, o ínflaton decai e ocorre o reaquecimento do universo. Contudo, alguns autores apontam a existência de uma fase intermediária, chamada de pré-aquecimento. O decaimento do ínflaton possui uma rica dinâmica não-linear. No primeiro estágio, a ressonância paramétrica promove o crescimento exponencial de alguns modos do ínflaton. Isto altera a dinâmica do modo homogêneo do ínflaton, promovendo uma reestruturação das cartas de ressonâncias da equação de movimento dos modos perturbativos. Desta forma, ocorre a transferência de energia para estes modos, até que o universo termaliza. Esta transferência de energia é típica de um sistema turbulento. Por se tratar de uma evolução não-linear, torna-se conveniente a implementação computacional de métodos numéricos. Neste contexto, os métodos espectrais têm se mostrado uma excelente ferramenta para estudar este tipo de sistema. Esta dissertação apresenta os resultados do esquema numérico desenvolvido para o modelo com potencial quártico, que será a base para os demais estudos a serem desenvolvidos. Como mostrado, este esquema é extremamente preciso e eficiente.

光系统Ⅱ核心天线复合物CP43和CP47的分离纯化及其光谱学特性的研究

应用改进DEAE-Toyopearl 650S阴离子交换柱层析从高等植物菠菜(Spinacia oleracea)中分离纯化了核心天线复合物CP43和CP47。并对它们的纯度和完整性色素种类和含量，以及色素分子的结合状态进行了研究并对色素分子间的能量传递机制进行了讨论。结果如下： 1、HPLC检测结果表明：纯化的CP43和CP47均只含Chla和β-Car两种色素分子，并且，平均每分子CP43多肽含19-20分子Chla和4-5分子β-Car;而平均每分CP47则含20-21分子Chla和3-4分子β-Car。 2、以436nm和480nm激发光激发样品得到的CP43和CP47的低温荧光发射光谱的最大荧光发射峰分别位于683nm和693nm。进一步发现，CP43和CP47，在相同条件下分别以436nm和480nm激发光激发样品得到的低温荧光发射光谱经归一化后几乎完全重叠，而且400-500nm波长范围内的激发光扫描得到的三维低温荧光发射光谱沿激发轴具有较好的对应关系，表明纯化的CP43和CP47都具有较高的完整性。 3、纯化的CP43和CP47的吸收光谱的红区最大吸收峰分别位于671nm和674nm。该光区的导数光谱均分辨出偏蓝区和偏红区两个子峰，CP43的这两个子峰分别位于669nm和682nm;而CP47的两个子峰则分别位于669nm和680nm。进一步用包含这两个子峰的高斯解析参数对红区最大吸收峰进行拟合，结果证明，拟合的曲线与实测曲线几乎完全吻合，这表明，CP43和CP47均至少包含两种不同状态的Chla分子。 3．1应用不同的变性温度处理CP43，发现随变性温度的不断提高，其红区最大吸收峰的峰值逐渐减小，四阶导数光谱分辨出的两个子峰同时减小，但差光谱显示：随处理温度的不断提高，这两个组分峰值的变化并不同步进行，较低温度范围内(55℃以下)682nm吸收峰下降明显，而较高温度范围内(55℃以上)，669nm吸收峰下降明显。 同时，随处理温度不断提高CP43脱辅基蛋白的结构也在不断发生变化，其变化过程明显表现出两个跃变阶段。这两个跃变阶段分别出现在40～50℃范围内和55～60℃范围内，恰与吸收光谱两个组分峰变化的转变过程相一致。这证明，CP43中分别位于669nm和682nm的不同的色谱组分即代表两种不同结合态的Chla分子，分别简称为“CP43-669”和“CP43-682”。它们在色素蛋白复合物中所处的环境不同，因而对蛋白质结构的依赖性不同，前者更高地依赖于蛋白复合物的整体构象，而后者则主要依赖于蛋白质的二级结构。 3.2 经不同的变性温度处理的CP47，其红区最大吸收峰的峰位逐渐蓝移，而吸收峰值无明显的变化，只有当处理温度提高到65℃以后，蓝移后的吸收峰值(669nm)才开始明显减小;四阶导数光谱表现为680nm吸收峰的信号逐渐下降669nm的吸收信号逐渐明显;处理减对照差光谱只观察到680nm吸收值的逐渐减少，而几乎观察不到669nm吸收值的变化。同时，随变性温度的不断提高，CP47的脱辅基蛋白的结构也发生相应的变化与CP43不同，蛋白结构变化最大的温度范围为60℃～65℃之间，但同CP47的峰位蓝移、导数光谱中680nm信号的减小，以及差光谱中680nm吸收值的减小相一致。由此认为，同CP43一样，CP47的吸收光谱中分辨出的分别位于669nm和680nm处的两个不同光谱组分亦分别代表两种不同结合状态的Chla分子，分别简称为“CP47-669”和“CP47-680”，与CP43中的相应组分对应，它们处于不同的蛋白环境中，从而对蛋白质结构变化的依赖性不同。 3.3 CP43和CP47的CD光谱表现出明显的正负双峰，表明色素分子间存在较强的激子相互作用。随变性温度的不断提高，正负CD双峰的信号逐渐减弱，变化过程与脱辅基蛋白结构的变化以及CP43-682的变化相一致，表明色素分子间的激子相互作用更高依赖于CP43-682和CP47-680。并认为CP43-682和CP47-680可能以二聚体或多聚体的形式存在，并且二聚体或多聚体的形成依赖于蛋白天然构象。而CP43-669和CP47-669则以单体的形式位于蛋白结构中相对伸展的区域。并提出：在CP43-682以CP47-680分子之间，激发能主要以激子偶合机制进行而在CP43-669，CP47-669分子间及CP43-669至CP43-682间，CP47-669至CP47-680之间激发能则主要以Foster机制进行。 4、以488nm激发光得到的CP43和CP47的共振拉曼光谱都具有全反式构型类胡萝卜素分子的四个典型特征峰由此认为CP43和CP47中的β-Car分子亦具有全反式构型;与溶于丙酮抽体物中的β-Car分子相比较，CP43和CP47中的β-Car分子的共振拉曼光谱中具有较强的960cm~(-1)的拉曼峰，表明，CP43和CP47中的β-Car分子具有扭曲的构象。 应用经归一化后的吸收光谱与荧光激发光谱相比较的办法发现CP43和CP47中存在β-Car分子和Chla分子间的能量传递其能量传递效率分别为29.8～29.9%和52.3～56.9%。这表明，在正常条件下，CP47中β-Car分子和Chla分子间的能量传递效率远大于CP43。此外，当选用蛋白结构变化最明显的热变性温度处理样品后，发现，不论CP43还是CP47中β-Car与Chla分子间的能量传递效率大大降低，表明，这两种色素分子间的能量传递严格依赖于蛋白复合物的天然构象，并认为，正常条件下，CP43和CP47内β-Car与Chla分子间的空间距离较近，可能不大于10A，CP43和CP47相比较，CP47内这两种色素分子间的距离更近。并进一步提出，在CP43和CP47中，β-Car到Chla分子间的能量传递最大可能以Dexter的电子交换机制进行。

Thin film coil design considerations for wireless power transfer in flat panel display

Wireless power transfer is experimentally demonstrated by transmission between an AC power transmitter and receiver, both realised using thin film technology. The transmitter and receiver thin film coils are chosen to be identical in order to promote resonant coupling. Planar spiral coils are used because of the ease of fabrication and to reduce the metal layer thickness. The energy transfer efficiency as a function of transfer distance is analysed along with a comparison between the theoretical and the experimental results. © 2012 Materials Research Society.

Excitation transfer in vertically self-organized pairs of unequal-sized InAs/GaAs quantum dots

The excitation transfer processes in vertically self organized pairs of unequal-sized quantum dots (QD's), which are created in InAs/GaAs bilayers with different InAs deposition amounts in the first and second layers, have been investigated experimentally by photoluminescence technique. The distance between the two dot layers is varied from 3 to 12 nm. The optical properties of the formed pairs of unequal-sized QD's with clearly discernible ground-state transition energy depend on the spacer thickness. When the spacer layer of GaAs is thin enough, only one photoluminescence peak related to the large QD ensemble has been observed as a result of strong electronic coupling in the InAs QD pairs. The results provide evidence for nonresonant energy transfer from the smaller QDs in the second layer to the larger QD's in the first layer in such an asymmetric QD pair.