The correlations of occurrence rate of whistlers in January during one solar cycle (1977–1987) at a low latitude station (Yamaoka, geomag. lat. 25°, L=1.26) with thunderstorm activity near its conjugate region and also with solar activity have been investigated, and it is found that the occurrence rate has no correlation with the lightning flashes near the conjugate point, while it is negatively correlated with solar activity. On the basis of these findings it is suggested that the ionospheric absorption is of major importance in the long-term variation of whistler occurrence rate, with the duct formation being of secondary effect, while the lightning activity is only a necessary condition for whistler occurrence. 相似文献
Interplanetary scintillation has observed high-latitude streams which show low speeds (400 km/s) within 0.3 AU and high speeds (700 km/s) beyond 0.3 AU. The foot points of these streams were located in the HeI coronal holes or at their boundaries. Since the IPS measurement is biased by one or several mechanisms, we investigated whether this acceleration phenomena could be caused by bias effects or not. Speed increase of more than 100 km/s is left without being explained by the bias effects. 相似文献
The process of comet formation through the hierarchical aggregation of originally submicron-sized interstellar grains to form micron-sized particles and then larger bodies in the protoplanetary disc, culminating in the formation of planetesimals in the disc extending from Jupiter to beyond Neptune, is briefly reviewed. The planetesimal theory for the origin of comets implies the existence of distinct cometary reservoirs, with implications for the immediate provenance of observed comets (both long-period and short-period) and their evolution as a result of planetary perturbations and physical decay, for example splitting and sublimation. The principal mode of cometary decay and collisional interaction with the terrestrial planets is through the formation and evolution of streams of cometary debris and hitherto undiscovered families of cometary asteroids. Recent dynamical results, in particular the sungrazing and sun-colliding end-state for short-period comet and asteroid orbits, are briefly discussed. 相似文献
On board the SOHO spacecraft poised at L1 Lagrange point, the SWAN instrument is mainly devoted to the measurement of large scale structures of the solar wind, and in particular the distribution with heliographic latitude of the solar wind mass flux. This is obtained from an intensity map of the sky Lyman emission, which reflects the shape of the ionization cavity carved in the flow of interstellar H atoms by the solar wind. The methodology, inversion procedure and related complications are described. The subject of latitude variation of the solar wind is shortly reviewed: earlier Lyman results from Prognoz in 1976 are confirmed by Ulysses. The importance of the actual value of the solar wind mass flux for the equation of dynamics in a polar coronal hole is stressed. The instrument is composed of one electronic unit commanding two identical Sensor Units, each of them allowing to map a full hemisphere with a resolution of 1°, thanks to a two-mirrors periscope system. The design is described in some details, and the rationale for choice between several variants are discussed. A hydrogen absorption cell is used to measure the shape of the interplanetary Lyman line and other Lyman emissions. Other types of observations are also discussed : the geocorona, comets (old and new), the solar corona, and a possible signature of the heliopause. The connexion with some other SOHO instruments, in particular LASCO, UVCS, SUMER, is briefly discussed. 相似文献
The use of some Arabic medieval solar and lunar eclipse records for the determination of secular changes in the Earth's rotation is critically reviewed. The published results derived from these data suggest a non-uniform decrease in the Earth's rotation rate over the last 27 cy. There is, however, up to this day no sound physical explanation for the deduced non-tidal oscillations, with an apparent period of about 1500 yr and a semi-amplitude of some 4 ms in the l.o.d., which overlayed to a constant secular tidal change in the Earth's rotation rate produce a net non-uniform deceleration of the Earth's rotation. In this paper we discuss a set of observations, which were executed by professional Arabic astronomers. We show by our analysis the way in which the non-uniform deceleration of the Earth's rotation was constructed. A correct reading of the Arabic medieval observations shows that they do not contradict a secular constant decrease in the Earth's rotation rate of nearly -4.6 10-22 rad s-2. This value is in accordance with other similar ones derived from ancient eclipse records and from satellite tracking data. 相似文献
In order to make renewable energy technology deployment strategies politically acceptable, many countries are linking them to other socio-economic goals. A controversial industrial policy tool that is increasingly popular is the use of local content requirements (LCRs). These regulate the extent to which certain projects must use local products and are often justified on the basis of supporting local employment and private sector development. The LCR debate has centred on the rights and wrongs of protecting infant industry, with little progress being made in finding common ground. This article aims to move beyond this stalemate to understand conditions under which LCRs might be an effective tool for promoting local manufacturing. To do so, an effectiveness framework is applied to LCRs for solar photovoltaics in India's National Solar Mission. The article finds that for LCRs to be effective, they must be (1) limited in duration and incorporate planned evaluation phases, (2) focused on technologies and components for which technical expertise is available and global market entry barriers are manageable, and (3) linked to training and promotion of business linkages and linked to support for other stages of the value chain and wider services integral to success of renewable energy industries.
Policy relevance
It is widely appreciated that governments need to support renewable energy technology deployment in order to mitigate climate change. However, policy makers face increasing pressure to link such support with other socio-economic goals, such as job creation, economic development, and poverty reduction. One such policy support mechanism is the use of local content requirements (LCRs) linked to feed-in tariffs. Policy makers are faced with a difficult choice as manufacturing interest groups lobby for the establishment of protection measures such as LCRs whilst the international trade community led by the World Trade Organization (WTO) seeks to limit their use. This difficulty is amplified by the limited information on the impact of LCRs on job creation and economic development. In this context, this article documents the use of LCRs in India's National Solar Mission and seeks to understand the conditions under which LCRs are an effective policy tool for building a competitive local manufacturing industry. 相似文献
This paper considers aspects of spatial justice in the processes of land acquisition for large-scale solar energy projects in the developmentalist context of India. It explores the case of one of the world’s largest solar park projects in Charanka, Gujarat. While the official rhetoric suggests an inclusive project for globally benign renewable energy production, the research reveals a more controversial land and power politics of renewable energy. It is argued, in particular, that the project increases the precariousness of vulnerable communities, who are exposed to the loss of livelihoods due to the enclosure of common land and extra-legal mechanisms through which land acquisitions for the project have reportedly taken place. This case exemplifies how solar mega-projects may manifest a regime of accumulation whereby low-carbon coalitions of interests can maximize their gains by dispossessing vulnerable social groups of their life-sustaining assets. 相似文献