A thermodynamic model including four irreversiblilities is used to investigate the optimal Performance a solar-driven thermoelectric generator. The efficiency of the system is derived and taken as and objective function for optimiztion. Some important curves, such as the efficiency of the system versus the operating temperature of the solar collector, the reduced current, and the load resistance, are obtained. These curves can reveal the performance charaterisistics of solar-driven thermoelectric generators. the maximum efficeiency of the system and the corresponding reduced current are derived for some special cases. The optimal matching of load resistance which is one of the kdy problems in the optimal design of solar-driven thermoelectric generators is discussed. New bounds of the key performance parameters, such as the efficiency, power output, and load resistance, are determined.

On the basis of the probability distribution of the various values of the fluctuation and the fundamental equation of thermodynamics of any given system, a simple and useful method of calculating the fluctuations is presented. By using the method, the fluctuations of thermodynamic quantities can be directly determined from the fundamental equation of thermodynamics. Finally, some examples are given to illustrate the use of the method.

A detailed study on global oceanic precipitation is carried out using the simultaneous TOPEX and TMR (TOPEX Microwave Radiometer) data. It is motivated by he success of a series of feasibility studies based on a few years of TOPEX TMR data, and the availability of a deeade-Iong new dataset thai spans I992-2002. In this context, a previously proposed rain probability index is improved by taking into account the dirtfference ol the dynamic range of the TOPEX-measured backscatter coefficients at the Ku and C hands and the lalitudinally complementary sensitivities of the TOPEX and TMR rain detections, leading to a refined joint precipitation index, which is generally consistent and quantitatively comparable with existing precipitation ciimatologies from the Global Preelpitation Climatology Project (GPCP) and the Comprehensive Ocean-Atmosphere Data Set (COADS). The new TOPEX-TMR precipitation climatology, on the one hand. confirms the fundamental features of global oceanic rainfall with additional details, and, on the other hand, reveals a number of interesting characteristics that are previously unknown or pnorly defined. 1) The spatial variability of the western Pacific "rain pool" (the atmospheric counterpart of the oceanic warm pool) is characterized by an interannual zonal migration, an annual cycle of meridional seesaw, and a semiannual cycle of expansion and shrinking. 2) The Pacific, Atlantic, and Indian Ocean interropical convergence zones (ITCZs) all have all annual cycle of cross-basin oscillation with east and west slops in JJA and DJE respectively. 31 A well-defined prominent rainy zone is observed in the southeast China Seas sound Taiwan Island, connecting with the Pacific rain pool in the south. 4) Between El Nifio and La Nina years, there is a systematic sign reversal of the geographical distribution of precipitation anomaly, which exists globally rather than in the tropical oceans only. 5) On a global basis, interannual and annual precipitation variabilities are of the same magnitude, bul the interannual (annual) com-ponent is more important for the Southern (Northern) Hemisphere. 6) For the tropical oceans, "season" defined by rainfall usually has a one quarter delay with respect to the coaesponding meteorological season. For the "'marine deserts" in the subtropical oceans, however, the raln-based season is found to be anticorrelated with the meteorological season. In addition, the annual cycle of the Atlantic precipitation is nearly 180 out of phase with respeet to thin of the Pacific and Indian Ocean for the same hemisphere.

In this paper, the equivalent combined systems of three-heat-source heat pumps are studied. It is pointed out that there may be three combined ways for us to conceive a reversible three-heat-source heat pump as a combined system having a reversible Carnot heat pump driven by a reversible Carnot engine. Whereas for an endoreversible three-heat-source heat pump affected by the heat resistances, there is only one combined way for us to conceive it as a combined system having an endoreversible Carnot heat pump driven by an endoreversible Carnot engine. Then, the fundamental optimum formula of a three-heat-source heat pump is derived simply and directly by using those of two-heat-source cycles. The optimal peformance of an endoreversible three-heat-source heat pump is thus discussed. The inherent relation between the two-and the three-heat-source cycles as well as the fundamental distinction between the reversible and the endoreversible three-heat-source cycles is also revealed. These results may enrich the theory of finite time thermodynamics, and provide some new theoretical bases for the exploitation and application of three-heat-source apparatus such as chemical heat pumps, absorption heat pumps, and so on.

We investigate the performance of a class of endoreversible-combined refrigeratkm cycles operating between a low-temperature heat reservoir at TL and a high-temperature heat reservoir at TH, and derive the optimal configuration and the rdation between the optimal coefficient of performance and the rate of refrigeration of these cycles. It is shown that the relation is similar to that of an optimal endoreversible refrigeration cycle. However, it is worth noticing that the overall heat resistace of a combined endoreversible refrigeration cycle is not identical with that of a single one, so that they are somewhat different from each other in performance. Simukaneously, it is pointed out that some performances of an endoreversible refrigeration cycle are quite different from those of an endoreversibIe power cycle.