The Selection of the Representative Year of Stream Flow for Electric Power Generation

An analysis of the actual state of the combination of the load and the hydro-and steam-power in a large combined hydro-steam power system is necessary for any economic comparison between various types of hydro- and steam-power generation; and for the power generation by a plant of the run-off-river type as well as of the pondage and storage types, it sometimes involves an inspection of the daily stream flow in connection with the daily load curve throughout a year. In such cases, it being difficult to draw a daily stream flow diagram for the future, it sometimes becomes necessary to select the representative year representing a typical stream flow from the data in the past. This paper describes the method for its selection

Estimation of the Average Stream Flow in the Immediate Future for Hydro-electric Power Generation

In making an economical study of a large combined hydro-steam power system, it is necessary to estimate the annual average available power of the rivers for any given year in the immediate future, and, especially for the control of a plant of pondage or storage type, to estimate the drought-seasonal average stream flow during the coming winter. In this paper we shall study the method for estimating the annual average stream flow by means of the theoretically based method of statistical extrapolation, and the method for estimating the drought-seasonal average stream flow during the coming winter by means of the method of statistical extrapolation for a time series with two members, by analysing the existing data of the seasonal average stream flows during winter and autumn over a number of recent years, including that for autumn of the estimated year, taking the data of certain rivers as examples

The Annual Average Stream Flow for Hydro-electric Power

In a large combined hydro-steam power system as in Japan, it is necessary to know what flowing condition of rivers may be expected to hold on an average for a long term, in order to plan for the economical development of hydro-power. However, the flowing condition not only varies in its total annual stream flow each year, but even seasonally within a given year, which makes it difficult for us to deal directly with the duration curves of stream flow or the daily stream flow curves which have been hitherto employed in developing hydro-power, so that we have to consider as a parameter the annual average stream flow for each year on which these depend. We need not take the average of all the data obtained in the past in order to estimate the annual average stream flow expected to hold for a long term to come, but must resort to the reasonable method of so-called time series analysis with its theoretical foundation, which takes into consideration the periodicity of the fluctuation contained in the stream flow and other factors. In this paper we propose to estimate the annual average stream flow expected to hold on an average for a considerably long term by means of an analysis, as easy and practical as possible, of a stream flow of comparatively small sample size

Purely excitonic lasing in ZnO microcrystals: Temperature-induced transition between exciton-exciton and exciton-electron scattering

Since the seminal observation of room-temperature laser emission from ZnO thin films and nanowires, numerous attempts have been carried out for detailed understanding of the lasing mechanism in ZnO. In spite of the extensive efforts performed over the last decades, the origin of optical gain at room temperature is still a matter of considerable discussion. In this work, we show that a ZnO film consisting of well-packed micrometer-sized ZnO crystals exhibits purely excitonic lasing at room temperature without showing any symptoms of electron-hole plasma emission, even under optical excitation more than 25 times above the excitonic lasing threshold. The lasing mechanism is shifted from the exciton-exciton scattering to the exciton-electron scattering with increasing temperature from 3 to 150 K. The exciton-electron scattering process continues to exist with further increasing temperature from 150 to 300 K. Thus, we present distinct experimental evidence that the room-temperature excitonic lasing is achieved not by exciton-exciton scattering, as has been generally believed, but by exciton-electron scattering. We also argue that the long carrier diffusion length and the low optical loss nature of the micrometer-sized ZnO crystals, as compared to those of ZnO nanostructures, plays a key role in showing room-temperature excitonic lasing

Expression and function of CCN2-derived circRNAs in chondrocytes

Cellular communication network factor 2 (CCN2) molecules promote endochondral ossification and articular cartilage regeneration, and circular RNAs (circRNAs), which arise from various genes and regulate gene expression by adsorbing miRNAs, are known to be synthesized from CCN2 in human vascular endothelial cells and other types of cells. However, in chondrocytes, not only the function but also the presence of CCN2-derived circRNA remains completely unknown. In the present study, we investigated the expression and function of CCN2-derived circRNAs in chondrocytes. Amplicons smaller than those from known CCN2-derived circRNAs were observed using RT-PCR analysis that could specifically amplify CCN2-derived circRNAs in human chondrocytic HCS-2/8 cells. The nucleotide sequences of the PCR products indicated novel circRNAs in the HCS-2/8 cells that were different from known CCN2-derived circRNAs. Moreover, the expression of several Ccn2-derived circRNAs in murine chondroblastic ATDC5 cells was confirmed and observed to change alongside chondrocytic differentiation. Next, one of these circRNAs was knocked down in HCS-2/8 cells to investigate the function of the human CCN2-derived circRNA. As a result, CCN2-derived circRNA knockdown significantly reduced the expression of aggrecan mRNA and proteoglycan synthesis. Our data suggest that CCN2-derived circRNAs are expressed in chondrocytes and play a role in chondrogenic differentiation

Stability of existing bridges improved by structural integration and nailing

AbstractTo examine whether and how the seismic stability of existing bridges can be substantially improved by integrating the girder, the abutments and the backfill, a series of shaking table tests were performed in 1 g. The tested small bridge models are (1) a conventional-type comprising a girder, supported by a pair of gravity-type abutments (without pile foundation) via bearings (fixed and movable), and unreinforced backfill, (2) the girder and the abutments of the above are integrated (without using bearings), (3) the backfill of the above is reinforced with two layers of large-diameter nails connected to the abutment top and the toe or the heel of the abutment footing and (4) the bottom nails of the above are replaced with longer ones connected to the toe of the abutment footing. Their dynamic behavior was analyzed as a damped single-degree-of-freedom system. The dynamic stability of the bridge was found to increase with an increase in (i) the dynamic strength against the response acceleration, (ii) the initial stiffness, (iii) the dynamic ductility (i.e., a smaller decreasing rate of stiffness during dynamic loading) and (iv) the damping ratio. When factors (ii) and (iii) are high enough, the natural frequency of a bridge can be kept much higher than the input frequency, and thus, the response acceleration can be kept low. All these factors can be improved by integrating the girder, the abutments and the backfill together with part of the supporting ground. In a series of static model tests, lateral cyclic displacements, caused by the seasonal thermal deformation of the girders with prototypes, were applied to the top of a small abutment model. The active failure in the backfill and the detrimental effects of large passive pressure, both developing due to the dual ratchet mechanism, can be effectively restrained by reinforcing the backfill and supporting the ground with nails connected to the top and the bottom of the abutments