6,524 research outputs found
Difference points in extractive and reactive cascades. II — Generating design alternatives by the lever rule for reactive systems
No full textUsing linear combinations of vectors in composition space, we formulate a lever rule for reactive distillation columns. This lever rule facilitates the proposal of alternative sequences of reactive distillation systems by allowing us to visualize how material balance constraints move as a Function of reaction "turnover". our approach uses the concept of a pseudo-feed, which is the composition that results from mixing column distillate and bottom products. Our lever rule for reactive distillation columns uses linear combinations of so-called reaction difference points, stoichiometric coefficient vectors of reactants and products, and composition vectors. When a reaction causes no change in the total number of moles, the reaction difference point moves to infinity (Hauan, Omtveit & Lien (1996). Paper 5f, A.I.Ch.E. Annual Meeting, Chicago, Hauan, Westerberg & Lien (1999a). Chemical Engineering Science, 55(6), 1053-1075, Hauan, Ciric, Westerberg & Lien (1999b). Chemical Engineering Science, in press). We show how to carry out all geometric constructions entirely within a finite composition domain by decomposing the total stoichiometric coefficient vector into product and reactant stoichiometric coefficient vectors. In this case the lever rule compares distances along two parallel vectors. For an infinite extractive difference point (Westerberg & Wahnschafft (1996). Advances in Chemical Engineering, 23, 63-170) we can confine all geometric manipulations when proposing alternative reactive distillation processes to a finite composition domain by combining the vectors in a different order. (C) 2000 Elsevier Science Ltd. All rights reserved
Enhancing TCP delivery over wireless networks
No full textWireless communication has become a significant life style in the daily use. The wireless communication can be used to extend the service of wired communication. Based on the idea
of simplicity, Transmission Control Protocol (TCP) has been used widely over wired network. When network applications take place using wireless link, TCP is still useful because partial
wired connection might be necessary. Although wired and wireless communication do share something in common, they have distinct features. Therefore, TCP needs to be adjusted to
fit in the wireless environment.This research aims to enhance wireless TCP performance. In order to study network protocols and behaviours, network simulators are often used for researchers to configure and
monitor the network factors and system states. Unfortunately, most network simulators cannot demonstrate what the real network does. They are applications. In this research, a network simulator based on the real Linux TCP/IP stacks is proposed. This simulator is able to not only simulate the wired network, but also allow users to extend its structure for live wireless emulation. By means of simulator and emulator, researchers can understand and configure detail factors for further experiments. Eventually, a new wireless TCP enhancement is proposed.In this research, some contributions are delivered. Firstly, a network simulator based on Linux TCP stacks is implemented. Secondly, a wireless emulator and test environment are built, so the wireless factors can be configured and performance can be monitored. Thirdly, a wireless TCP mechanism, TCP NewZag, is proposed. Finally, several experiments to show the value of NewZag are reported in the thesis
Qui doit nourrir l'enfant dont le père est absent ? Le cas de la Belgique
No full textL'article s'inscrit dans le dossier thématique "Politiques du père" de la revue Lien social et politique - RIAC. L'auteur présente un aperçu de la manière dont se pose, en Belgique, la question « Qui doit nourrir l'enfant dont le père est absent ? », à la fois sur le plan socio-démographique et sur le plan politique et juridique. Après avoir tenté d'évaluer l'ampleur du phénomène des familles monoparentales matricentrées dans la Belgique contemporaine, il traite de la problématique au regard du droit civil puis du droit social. Il présente le dispositif public de lutte contre la pauvreté qui se met en œuvre, notamment, vis-à-vis des ménages à père absent confrontés à une situation de précarité sociale, et essaie de cerner le rôle joué par le départ du père dans la précarisation sociale des familles monoparentales matricentrées.Who is Responsible for Supporting the Child When the Father is Absent? The situation in Belgium The author of this paper outlines socio-demographic, political and legal issues in Belgium linked to the question of "who is responsible for supporting the child when the father is absent ?" After trying to assess the scope of the phenomenon of mother-headed single-parent families in Belgium today, he looks at the issues from the perspective of civil and social law. He examines current government measures to combat poverty, especially those targeted to households with an absent father that are faced with a precarious social and financial situation, and he attempts to determine the role the departure of the father has played in the increasingly precarious situation of mother-headed single-parent families
Improving TCP performance over wireless networks
Get PDFThis paper proposes a novel end-to-end congestion control mechanism called TCP NewZag. NewZag is simple and effective in dealing with random packet loss, so it can improve TCP performance in the wireless network. TCP NewZag proposes two new mechanisms: (1) a new end-to-end loss differentiation algorithm (LDA); (2) the adjustments of TCP NewReno multiplicative decrease algorithm. These two mechanisms only require the adjustment of TCP sender side, while the receiver side protocol remains the same. Based on experimental measurements of single link, it is shown that NewZag achieves significant throughput improvement when the wireless random packet losses occur. Compared with NewReno in 0.5% random packet loss rate, 20% throughput improvement can be demonstrated
(17(3):17-25)EFFECTIVENESS OF VARIOUS INSECTICIDES FOR DESTROYING ORINTAL FRUIT FLY, DACUS DORSALIS HENDEL, INFESTATIONS IN GREEN MATURE BANANA
No full text（一） EDB. Nankor，sumithion，Lebaycid四種藥劑對青香蕉行滅蠅浸漬時，以EDB，Sumithion及Lebaycid之效果最佳，Nankor較差而不適宜於植物檢疫上之要求。將來外銷香蕉須行此項處理時，EDB最低濃度應為0.3ml/L浸漬5分鐘或0.5ml/L浸漬3分鐘，最高不得超過0.9ml/L以上。Sumithion與Lebaycid之實用度則為0.025%～0.05%浸漬30~60秒。
（二） 燻蒸處理不論以EDB或Phostoxin，在完全殺蟲之濃度範圍內，皆能引起藥害或催熟作用，故不適合於蕉果之商品處理（Commodity treatment）。
（三） 在實用濃度範圍內（有完全殺蟲而又不損及蕉果之濃度），經EDB浸漬處理後之青香蕉，無催熟現象發生，且經加工黃熟後，亦不改變外觀或味覺。
（四） Sumithion與Lebaycid之機械噴藥，在較短時間內處理時，効果較浸漬處理為差。不過若噴藥時間延長至60秒以上，即使在較低之0.025%濃度內，也可殺死蕉果內全部之果蠅卵及幼蟲。至於噴藥前之沖水洗滌與否，對殺蟲劾果並無影響。
The purpose of this study was to clarify the effect of five insecticides to destroy the oriental fruit fly, Dacus dorsalis Hendel, infestation in green mature banana, and to see if its effect can meet the requirements of plant quarantine, The insecticides used in this experimentation are E D B (Ethylene dibromide), Nankor, Sumithion, Lebaycid and Phostoxin. The phytotoxicity of some insecticides on green banana also were made. Results obtained from this study are summarized as follows:
1. In comparison with the effectiveness of E D B, Nankor, Sumithion and Lebaycid water dipping, EDB, Sumithion and Lebaycid gave an excellent effect on the killing of fly eggs and larvae hidden in banana fruit. However, Nankor gave less effectiveness and thus Nankor is not suitable for export banana treatment.
The data shown below are to be referred in the event when such treatment is required for export babana.
EBD: Minimum concentration: 0.3 ml/L. for 5 minutes dipping or 0.5 ml/L for 3 minutes dipping. Maximum concentration shall be 0.9 ml/L.
Sumithion and Lebaycid: Minimum concentration 0.025-0.05%. Immersion time 30-60 seconds.
2. Within the range of concentration of complete mortality, either fumigation of EDB or Phostoxin are not adoptable for the commodity treatment of export banana, because it may cause banana heavely phytotoxicity or hasten the ripening of banana.
3. No further ripening has been found to the banana which was dipped in the practical concentration of EDB solution, i. e., the concentration of thorough killing fruit fly and cause no damage to the fruit. The same banana after ripening process, never change its appearance or its taste.
4. A special design banana sterilization machine which equiped with automatic sprayer has been employed in this experimentation. The data show that the effect of mechanical spray of Sumithion or Lebaycid is rather bad than the dipping method of the same chemicals. However, a better effect can be expected if the treatment time has been lengthened to 60 seconds or more. By such length of time, it can kill all fruit fly eggs or larvae infestaticn in banana even at the comparatively lower ccntcntration of 0.025% or less. Futhermore, the effect of killing would not be affected no matter the banana washed by water before mechanical spray or not
The ‘helicopter parent’ and the paradox of intensive parenting in the 21st century
Get PDFThe term ‘helicopter parent’ has become highly visible in public and professional commentary about parenting and in culture more generally, notably in North America and the UK. A small body of sociological work has highlighted the paradox of this phenomenon, given by often dramatized expressions of concern with ‘excessive’ parental involvement with children associated with the term, within a culture of intensive parenting. This article builds on this work in two ways. We situate the now ubiquitous description of parental mistakes as ‘helicoptering’ by discussing discursive antecedents of the present label found in 20th century terminology such as ‘overparenting’, ‘smothering’ and ‘coddling’, noting their co-existence with accounts of ‘bad mothers’ as distant and uninvolved. Second, through analysis of the term ‘helicopter parent’ in the British news media in the late 20th and 21st centuries, we assess how present concerns with parental proximity to children are constructed. We found the most prominent themes in media coverage to be parental love ‘gone wrong’, parental ‘pushiness’, and the class position of the helicopter parent. We suggest our analysis shows the ‘helicopter parent’ can be best understood as an aspect of 21st century vernacular, expressing recoil at the perceived outcomes of intensive parenting, but leaving its basic premises regarding parental culpability for individual and social pathologies intact. We conclude that, for sociologists, an important feature of the helicopter parent term is the characterisation of problem parents as middle class and suggest this construction of the cause of parental deficiencies is an important concern for the study of parenting cultures going forwards
Cesarean Section in the National Taiwan University Hospital Between 1951-1985:Indicence and Indciation
No full textLien in Civil and Commercial Relations
No full textLīdz ar grozījumiem Komerclikumā likumdevējs Latvijas tiesību sistēmā ir ietvēris komersanta aizturējuma tiesību, vienlaikus aktualizējot arī aizturējuma tiesības piemērošanu. Diemžēl aizturējuma tiesības institūta izpratne Latvijas tiesību zinātnē skaidrota ir ļoti maz, līdz ar to rodas problēmas ar tās piemērošanu praksē. Ņemot to vērā, darba autors izvirza mērķi izskaidrot aizturējuma tiesības izpratni atbilstoši mūsdienu privāttiesību tendencēm un rast risinājumu ar komersanta aizturējuma tiesības piemērošanu saistītajai tiesību problemātikai. Darbā autors analizē aizturējuma tiesības institūtu veidojošos elementus un izdara secinājumus par to pareizu piemērojamību, skatoties arī caur ārvalstu tiesību zinātnes prizmu. Vienlaikus autors sniedz priekšlikumus arī komersanta aizturējuma tiesības piemērošanas efektivitātes uzlabošanai.With the amendments in the Commercial Law, the legislators have included the merchant’s lien, simultaneously actualizing the lien enforcement. Unfortunately, the purpose of lien in the Latvian law science has been explained poorly, thus creating problems in its application in practice. Taking this into account, the author aims to clarify the purpose of lien according with the modern trends of Private Law and to find solutions to the problems related to the application of merchant’s lien. The author analyzes the elements of the lien and draws conclusions about their proper application, looking through the prism of the foreign law science. Meanwhile, the author provides suggestions to increase the efficiency of the merchant’s lien
A graphical method for designing reactive distillation columns II. The McCabe-Thiele method
No full textThis paper shows how to construct a McCabe-Thiele diagram for binary reactive distillation. We consider two types of reaction that are consistent with binary mixtures: isomerization (R1 <-> P1) and decomposition (R1 <-> 2P1). We can account for reaction by tracking only two features of the diagram while constructing it. First, the intersection point of the operating line with the y = x line can be called the reactive cascade difference point, and it moves in a manner directly determined by the ratio of the molar extent of reaction (or reaction turnover flowrate) to the product flowrate. Second, the heat supplied (removed) by reaction decreases (increases) the slope of the operating line while not changing the location of the reactive cascade difference point. By tracking these two features, one can quickly sketch such a diagram. We also show how to construct a McCabe-Thiele diagram if the reaction zone is only at the feed stage. Finally, we discuss a case in which the reactive cascade difference point moves past the feed composition and the bottom product composition is less pure than the feed composition
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