Analysis of the mechanisms for impaired high-temperature, high-speed performance of 1.3 μm InGaAsP lasers

In this paper, the static and dynamic performance of multi quantum-well (MQW) 1.3 μm InGaAsP Fabry Perot lasers is assessed experimentally and theoretically to identify the mechanisms responsible for impaired high speed performance at elevated temperature. Initially, threshold currents and spontaneous emission spectra are characterized for a range of temperatures from room temperature to 85 °C to indicate a significant increase in non-radiative current contributions. Preliminary estimates are made for the contributions of leakage and Auger recombination rates, found from the dependence of integrated spontaneous emission with carrier density. Drift-diffusion modelling is found to accurately predict the trend of threshold currents over temperature. Using gain modelling good agreement is found between the measured and predicted integrated spontaneous emission intensity. Gain measurements at 85 °C indicate a reduction in RIN frequency to 63% of the 25 °C value which matches well with experimental small signal performance.

Analytical model for the 3D-RESURF effect

This paper presents an analytical model for the determination of the basic breakdown properties of three-dimensional (3D)-RESURF/CoolMOS/super junction type structures. To account for the two-dimensional (2D) effect of the 3D-RESURF action, 2D models of the electric field distribution are developed. Based on these, expressions are derived for the breakdown voltage as a function of doping concentration and physical dimensions. In addition to cases where the drift regions are fully depleted, the model developed is also applicable to situations involving drift regions which are almost depleted. Accuracy of the analytical approach is verified by comparison with numerical results obtained from the MEDICI device simulator.

Pelagic fishery resources of Sri Lanka and its present level of exploitation with special reference to off-shore and deep-sea waters

Pelagic resources around Sri Lanka may be categorized into three major groups: (1) the small pelagic varieties such as the sprats, halmessa, sardines (salaya, soodaya), and herrings (hurulla). (2) the medium size pelagic species such as the mackerel (kumbala and bolla), barracuda (jeela), seer Spanish mackerel (thora), frigate mackeral (alagoduwa), mackerel tuna (atawalla) and the skipjack (balaya). (3) the large size fishes such as yellow fin tuna (kelawalla), big eye tuna, marlins (koppora and gappara), sail fish (thalapath), sharks (mora) and rays (maduwa). Production levels of exploited resources are noted, and seasonal patterns and annual in their abundance are considered. On the basis of observations and estimations of the existing fisheries, and the results of experimental fishing, figures are presented of the potential yield of those species already exploited. The development of that potential depends on the development of modern techniques of pole and line fishing, application of tuna longline and shark longline, increasing the number of units of drift nets and the introduction of a bait fishery for the longline and pole line fishery. Some features upon which the successes of any venture to exploit such resources are noted, particularly those which relate to the nature of the fishing vessels used.

Fishing gear and methods for off-shore fishing in Sri Lanka

The author describes the commercial viable off-shore fishing methods for catching known commercial resources available around Sri Lanka. He also describes the in-shore fishing methods such as bait fishery which are related and of prime importance for carrying out certain off-shore methods. The paper is intended as a background for the description of fishing methods. The methods discussed are: (1) Longlining for large pelagic species such as large tuna (yellow fin, big eye), shark, spearfish and others; (2) Drift-netting for small and large tuna species (skipjack, yellow fin and others), shark, spearfish, etc.; (3) Pole and line for all deep-sea pelagic species such as skipjack, yellow fin, frigate mackerel, etc.; and (4) Purse seining (small scale) for small pelagic species suitable as bait fish for pole and line and longline fisheries.

An analysis of the experimental pole and line fishery conducted around Sri Lanka by Nichiro Fishing Company of Japan

Under a joint agreement the Government of Sri Lanka and the Nichiro Fishing Company of Japan have undertaken an experimental pole and line fishery around Sri Lanka with a view to determining the feasibility of establishing a joint commercial venture. 3 Japanese vessels conducted trials during the period March 1973-October 1974. Details of the vessels and cruises are given. A variety of fish were tried as bait, and the selection of appropriate bait is discussed. Catches and catch and effort statistics are presented, with tables showing distribution of the tuna. The results of the trials were below expectations, and are in part attributed to bait availability, and unfavorable weather conditions. Seasonal variation of the type of fishery is suggested in order to take account of this, and it is concluded that a fishery based on 45/50 ft combined pole and line and drift net fishing vessels might prove feasible.

Modeling of MOS-side carrier injection in trench-gate IGBTs

A compact trench-gate IGBT model that captures MOS-side carrier injection is developed. The model retains the simplicity of a one-dimensional solution to the ambipolar diffusion equation, but at the same time captures MOS-side carrier injection and its effects on steady-state carrier distribution in the drift region and on switching waveforms. © 2007 IEEE.

Spice modelling of the superjunction IGBT

This paper presents a SPICE model of the SuperJunction Insulated Gate Bipolar Transistor (SJIGBT) [1]. SPICE simulation results are in good agreement with the DESSIS simulation results under DC conditions. This model consists of an intrinsic MOSFET and a parallel combination of a wide and a narrow base pnp BJTs. A parasitic JFET is also included to account for the restricted current flow between two adjacent p-wells. In addition the JFET component also models the additional depletion region caused by the transverse junction at the upper side of the n-drift region where the current is mainly transported via majority carriers.

Effect of colour on the catch of gill nets

The effect of white, green, blue and yellow coloured drift gill nets on their catch with respect to Scomberomorus guttatus (Schneider), Scomberomorus commerson (Lacepede), Scomberomorus lineolatus (Cuvier), Parastomateus niger (Bloch), Euthynnus ajjinis (Cantor) and sharks Carcharius melanopterus is discussed. White nets were more effective for S. guttatus while the coloured ones caught more of P. niger. Blue had no significant effect for sharks. In the case of S. lineolatus, S. commerson and E. affinis no preference to colour was noted.

Observation on the lunar and tidal influence on gill netting in the Bay of Bengal

The effect of lunar and tidal influence on the landing of pelagic fish with drift gill nets has been studied for the first time from Bay of Bengal along the Orissa coast. The catchability of the gear was highest during the first quarter and lowest in the fourth quarter of the moon. The variation in catch rates during the four different quarters was not statistically significant. Contrary to the earlier belief, landing with gill net was not poor during the moonlit nights. The extensive use of bluish grey nylon twine matching with seawater in place of indigenous hemp or cotton twine, has largely eliminated the visibility of gear during the brighter phase of the moon. The rate of exploitation was found to be significantly higher during the nights of neap tide, compared to those of spring tide. A plausible explanation for this phenomenon has been offered.

Preliminary observations of the use of under-water light in fish catch

Experiments with drift gill net with under-water lights were carried out in the sea and estuarine region along with a control net of the same specifications without any light in the same fishing ground for comparison. The experimental net caught more fish in number and weight than the control. Fishes like pomfrets (Pampus chinensis, Parastromafeus niger), seer (Scomberomorus spp), hilsa (Ilisha spp) etc showed positive phototaxis and were gilled encircling the point of illumination. Young skates (Mobula spp) and Polynemus tetradactylus were antiphototactic. The number of fishes caught increased with increase in period of illumination. The catch of larger fishes was maximum at 60 mts of illumination and the total catch increased with increase in intensity of light. Additional cost of operation with under-water light was Rs 1-25 per hr but the catch was 4 to 5 times greater than that of the control net.

Status and prospects of mackerel and tuna fishery in Bangladesh

Present status and future prospects of mackerel and tuna fisheries in Bangladesh were assessed during July 2003-June 2004. The work concentrated on the fishing gears, length of fishes, total landings and market price of the catch and highlighted the prospects of the fishery in Bangladesh. Four commercially important species of mackerels and tuna viz. Scomberomorus guttatus, Scomberomorus commerson, Rastrelliger kanagurta, and Euthynnus affinis were included in the study. About 95% of mackerels and tuna were caught by drift gill nets and the rest were caught by long lines (4%) and marine set-bag-net (1%). Average monthly total landing of mackerels and tunas was about 264 t, of which 147 t landed in Cox's Bazar and 117 t in Chittagong sites. Total catches of the four species in Cox's Bazar and Chittagong sites were found to be 956 and 762 t, respectively. The poor landing was observed during January-February and the peak landing was in November and July. Gross market value of the annual landing of mackerels and tunas (1,718 t) was found to be 1,392 latch taka. Nevertheless, the mackerel and tuna fisheries in Bangladesh are increasingly contributing to the marine fish production of the country and have very good potential for further expansion for both domestic and export market.

大陆漂移与云南胡蜂的扩散分布

云南高原位于北纬21°9′～29°15′和东经97°39′～106°12′之间,总面积394000 km2 ,地质和气候、植被非常复杂。大 陆漂移和冰期的进退是影响昆虫起源和演替的一个重要原因。昆虫的祖先是起源于一个统一大陆,在这个大陆上共 同起源,共同进化,随着原始大陆的分离和漂移,把这些类群运载到各地,形成现今昆虫分布格局。昆虫的扩散是以中 心分布方式成环状向周围扩散的。云南胡蜂的祖先是来自冈瓦那古陆。有两支昆虫进入云南,其中一支来自喜马拉 雅山,另一支来自缅甸。冰期是导致南北生物互相混合和渗入的重要因素。胡蜂的特有类群是在冈瓦那古陆分裂之 后才发展起来的。其祖先最早是分布在原始古陆较狭窄的区域内。

Characterization of genetic biodiversity of Nile perch, Lates niloticus, Tilapiines, Haplochromine flock and Ningu (Labeo victorianus) in the Victoria Lake Basin: an overview

Genetic biodiversity is the vaflatlOn among individuals within and between units of interbreeding individuals (populations) of a species. It includes inheritable and transmittable differences that occur between individuals andlor popuhitions of a given species through reproductive interaction. There exists enormous variability among individuals andlor populations of a species for most living organisms, and most of this variation is inheritable. differences among individuals arise through mutation and via recombination of genes during meiosis. These ifferences are then transmitted to successive generations through sexual reproduction and maintained in the populations through processes such as natural selection and genetic drift. Unfortunately much of this variation is normally threatened and often in danger of extinction because most focus in conservation of natural resources is put at saving species or habitats than varieties or strains of a species

How much do we spend to save? Calculating the embodied carbon costs of retrofit

The drive to reduce carbon emissions from domestic housing has led to a recent shift of focus from new-­‐build to retrofit. However there are two significant differences. Firstly more work is needed to retrofit existing housing to the same energy efficiency standards as new-­‐build. Secondly the remaining length of service life is potentially shorter. This implies that the capital expenditure – both financial and carbon -­‐ of retrofit may be disproportionate to the savings gained over the remaining life. However the Government’s definition of low and zero carbon continues to exclude the capital (embodied) carbon costs of construction, which has resulted in a lack of data for comparison. The paper addresses this gap by reporting the embodied carbon costs of retrofitting four individual pilot properties in Rampton Drift, part of an Eco-­‐Town Demonstrator Project in Cambridgeshire. Through collecting details of the materials used and their journeys from manufacturer to site, the paper conducts a ‘cradle-­‐to-­‐gate’ life cycle carbon assessment for each property. The embodied carbon figures are calculated using a software tool being developed by the Centre for Sustainable Development at the University of Cambridge. The key aims are to assess the real embodied carbon costs of retrofit of domestic properties, and to test the new tool; it is hoped that the methodology, the tool and the specific findings will be transferable to other projects. Initial changes in operational energy as a result of the retrofit works will be reported and compared with the embodied carbon costs when presenting this paper.

Taxonomía y distribución de los poliquetos pelágicos del Atlántico Sudoccidental

This work is based on the analysis of 420 planktonic samples of 7 oceanopraphic cruises distributed over the Argentine, Uruguayan and South brasilian continental shelf (SW Atlantic ocean), as well as from some oceanic sectors, adjacent to the continental slope. Vertical hauls were performed in all stations from 100 m depth to surface, except in the Walter Herwig cruise (where vertical hauls were predominantly performed out of slope sectors, between 300 and 500 m depth to surface) and Productividad cruise in which only surface waters were hauled. A list of 27 species are determined, corresponding to 5 families: Iospilidae (3 species), Lopadorrhynchidae (4), Alciopidae (9), Typhloscolecidae (5) and Tomopteridae (6). Larvae and epitokous forms of benthonic species are not taken into account. The genus Iospilus is revised, Pariospilus and Iospilopsis being considered their synonyms; the identity of Pariospilus affinis Viguier is maintained, being transferred to the genus Iospilus. The species Vanadis studeri Apstein is redescribed and its synonymy is established. The taxonomic value of the apical glands of Tomopteris species is discussed and some specimens are found to coincide with T. kefersteini in relation to the mentioned glands. All the species found in this work are described and illustrated, a systematic key being added for their identification. Considering the vertical nature of the hauls, it was not possible to specify the habitats of the different species; for this reason they are grouped as species from subtropical and subantartic areas of influence. The first group, made up of 17 species, shows and evident graduation in its latitudinal distribution, some of them being more restricted in their distribution than the others. The second group, of 4 species, is found south to the tropical convergence, in transitional waters, towards cold sectors. The third group, of 6 species, is found to be distributed all along the continental shelf, in subtropical and subantartic regions, and extending their distribution northwards, possibly related to deep water levels. The general scheme is coincident with the distribution of other planktonic groups (Copepods, Euphausiids). As a general feature, neither coastal nor shelf water specimens of pelagic Polychaeta were found, with exception of T. septentrionalis. A comparison with the results in Tebble's paper (1960) in the southwest Atlantic ocean is made, 12 of our species being coincidently found in the same hydrological area by that author. The drift of the main water masses of the South Atlantic ocean is accepted as a possible cause for the distribution of the pelagic Polychaeta of the southwest Atlantic regions.