Layout to circuit extraction for three-dimensional thermal-electrical circuit simulation of device structures

In this paper, a method is proposed for extraction of coupled networks from layout information for simulation of electrothermal device behavior. The networks represent a three-dimensional (3-D) device structure with circuit elements. The electrical and thermal characteristics of this circuit representation are calculated with a circuit simulator. Spatial potential distributions, current flows, and temperature distributions in the device structure are calculated on the spatial coordinates. This simulation method can be placed between device simulation and (conventional) circuit simulation. It has been implemented in a circuit simulator and is demonstrated for simulation of self-heating in a bipolar low frequency power transistor. The main advantage of this simulation method is that not only the 3-D thermal behavior of the whole chip is simulated, but that this is also directly coupled to the electrical device behavior by means of the power dissipation and temperature distribution in the device. This offers the possibility for the circuit designer to simulate 3-D, coupled, thermal-electrical problems with a circuit simulator. As an example, the influence of the emitter contacting on the internal temperature and current distribution of a BJT is investigate

Agriculture Diversification in the Mekong Delta: Farmers' Motives and Contributions to Livelihoods

Although specialization is the global trend in agriculture, integrated farming systems have emerged in Vietnam. An important motive was the desire to improve the livelihoods and the diet of the nuclear families; this was evident in the analysis using the household life cycle of five phases. Off-farm diversification was especially important for a new household. At the onset of expansion, the new mothers replaced off-farm with homebound activities. During expansion the farmers increased virtual farm size by keeping more livestock; during accumulation, they invested in land or education, and during consolidation old couples adjusted farm activities to their labor capacity. Livestock, including fish, was essential for livelihood. The distribution of goats instead of cattle by credit or by "passing-on-the-gift " was far more effective for poverty alleviation. Technological innovations on the cultivation of rice and fruits, and the breeding of fish were essential for change. The improved food security and reduced cash income from rice after the 1986 reforms pushed farmers to take risks. The farm area and number of component farm activities providing cash determined the level of cash income from agriculture. Farms with at least four flows of biomass between components earned more, demonstrating that real integration improved profits. A minimum area of land in, or close to, the homestead, and know-how are required for an effective integration of components.Mekong Delta, agricultural diversification

Aquaculture Stewardship Council (ASC) ontwikkeltraject meerval

De Nederlandse viskweeksector bestaat uit bedrijven die hun vis kweken in Recirculatiesystemen (RAS), met name de meervalsector (lees Afrikaanse meerval en Claresse) wordt gestimuleerd om in te spelen op de trend van certificering voor duurzaamheid om zich hiermee aanvullend te onderscheiden van andere aquacultuurproducten). Nederlandse kwekers kunnen hun bedrijven (en hiermee het productieproces) al laten certificeren voor Milieukeur, maar dit label is beperkt beschikbaar in Nederlandse supermarkten en geeft in Nederland onvoldoende en andere Europese landen geen herkenning voor consumenten. De Aquaculture Stewardship Council (ASC) biedt die mogelijkheid wel. Een inventarisatie naar de mogelijkheden om een standaardisatietraject voor Afrikaanse meerval / Claresse te realiseren is uitgevoerd. Hierbij zijn de mogelijke ambitieniveaus, benodigde procedures en de bijbehorende kosten in kaart gebracht. Aanvullend is een studie uitgevoerd voor tarbot. Een certificeringstraject in het kader van ASC is voor de Nederlandse meerval (en tarbot) sector haalbaar, de kosten en baten zullen echter afgewogen moeten worden. Er dienen hierbij keuzes gemaakt te worden in de richting van een dergelijk proces. Er kan gekozen worden voor een proces in de richting van standaardisering voor Afrikaanse meerval/Claresse. Hiermee is het traject direct gebonden aan een bredere aanpak naar Afrikaanse landen (met name Nigeria), aangezien hier een groot deel van de Afrikaanse meerval productie plaatsvindt. Daarnaast zijn er mogelijkheden om een standaardisatietraject in te gaan voor een hogere meervalgroep de Clariidae, waaronder de in Nederland gekweekte soorten vallen. De processen worden hiermee verbreed naar oa Aziatische landen. De kosten en procesduur zullen hiermee toenemen, de reikwijdte zal groter zijn, de overige effecten worden in het rapport weergegeven. Alle trajecten die voor het behalen van een ASC certificering (en voorafgaand de standaarden) gevolgd worden dienen aan de eisen van ISEAL (International Social and Environmental Accreditation and Labelling Alliance) te voldoen. Dit vergt een adequate procesbeschrijving en bewaking, waarin alle stakeholders de mogelijkheid dienen te krijgen om input en invulling aan het proces te geven. De kosten voor een procedure rond Afrikaanse meerval bedragen ruim 440 k€ (schatting). Een uitgebreidere variant voor alle meervalsoorten (exclusief pangasius) zal 675 k€ bedragen. Voor de Nederlandse meervalsector zijn al verschillende duurzaamheidsinventarisatietrajecten doorlopen. In veel gevallen zijn de data om te komen tot een standaard aanwezig. Deze kunnen in de processen worden ingebracht. Voor ASC zullen er nog aanvullende eisen gesteld worden, welke in het ontwikkelproces nader onderbouwd dienen te worden. Het behoeft aanbeveling om, naast een traject voor vissoorten, de mogelijkheden te beoordelen voor een ontwikkelingstraject voor ASC standaarden op het niveau van kweeksystemen

Understanding Galaxy Formation and Evolution

The old dream of integrating into one the study of micro and macrocosmos is now a reality. Cosmology, astrophysics, and particle physics intersect in a scenario (but still not a theory) of cosmic structure formation and evolution called Lambda Cold Dark Matter (LCDM) model. This scenario emerged mainly to explain the origin of galaxies. In these lecture notes, I first present a review of the main galaxy properties, highlighting the questions that any theory of galaxy formation should explain. Then, the cosmological framework and the main aspects of primordial perturbation generation and evolution are pedagogically detached. Next, I focus on the ``dark side'' of galaxy formation, presenting a review on LCDM halo assembling and properties, and on the main candidates for non-baryonic dark matter. It is shown how the nature of elemental particles can influence on the features of galaxies and their systems. Finally, the complex processes of baryon dissipation inside the non-linearly evolving CDM halos, formation of disks and spheroids, and transformation of gas into stars are briefly described, remarking on the possibility of a few driving factors and parameters able to explain the main body of galaxy properties. A summary and a discussion of some of the issues and open problems of the LCDM paradigm are given in the final part of these notes.Comment: 50 pages, 10 low-resolution figures (for normal-resolution, DOWNLOAD THE PAPER (PDF, 1.9 Mb) FROM http://www.astroscu.unam.mx/~avila/avila.pdf). Lectures given at the IV Mexican School of Astrophysics, July 18-25, 2005 (submitted to the Editors on March 15, 2006

The internal structure of poly(methyl methacrylate) latexes in nonpolar solvents

Hypothesis: Poly(methyl methacrylate) (PMMA) latexes in nonpolar solvents are an excellent model system to understand phenomena in low dielectric media, and understanding their internal structure is critical to characterizing their performance in both fundamental studies of colloidal interactions and in potential industrial applications. Both the PMMA cores and the poly(12-hydroxystearic acid) (PHSA) shells of the latexes are known to be penetrable by solvent and small molecules, but the relevance of this for the properties of these particles is unknown. Experiments: These particles can be prepared in a broad range of sizes, and two PMMA latexes dispersed in n-dodecane (76 and 685 nm in diameter) were studied using techniques appropriate to their size. Small-angle scattering (using both neutrons and X-rays) was used to study the small latexes, and analytical centrifugation was used to study the large latexes. These studies enabled the calculation of the core densities and the amount of solvent in the stabilizer shells for both latexes. Both have consequences on interpreting measurements using these latexes. Findings: The PHSA shells are highly solvated (∼85% solvent by volume), as expected for effective steric stabilizers. However, the PHSA chains do contribute to the intensity of neutron scattering measurements on concentrated dispersions and cannot be ignored. The PMMA cores have a slightly lower density than PMMA homopolymer, which shows that only a small free volume is required to allow small molecules to penetrate into the cores. Interestingly, the observations are essentially the same, regardless of the size of the particle; these are general features of these polymer latexes. Despite the latexes being used as a model physical system, the internal chemical structure is complex and must be fully considered when characterizing them

Breaking ‘128-bit Secure’ Supersingular Binary Curves

In late 2012 and early 2013 the discrete logarithm problem (DLP) in finite fields of small characteristic underwent a dramatic series of breakthroughs, culminating in a heuristic quasi-polynomial time algorithm, due to Barbulescu, Gaudry, Joux and Thomé. Using these developments, Adj, Menezes, Oliveira and Rodríguez-Henríquez analysed the concrete security of the DLP, as it arises from pairings on (the Jacobians of) various genus one and two supersingular curves in the literature, which were originally thought to be 128-bit secure. In particular, they suggested that the new algorithms have no impact on the security of a genus one curve over F21223 , and reduce the security of a genus two curve over F2367 to 94.6 bits. In this paper we propose a new field representation and efficient general descent principles which together make the new techniques far more practical. Indeed, at the ‘128-bit security level’ our analysis shows that the aforementioned genus one curve has approximately 59 bits of security, and we report a total break of the genus two curv

On the Static Diffie-Hellman Problem on Elliptic Curves over Extension Fields

We show that for any elliptic curve E(Fqn ), if an adversary has access to a Static Diffie-Hellman Problem (Static DHP) oracle, then by making O(q1− 1/n+1) Static DHP oracle queries during an initial learning phase, for fixed n > 1 and q → ∞ the adversary can solve any further instance of the Static DHP in heuristic time O˜(q1− 1/n+1). Our proposal also solves the Delayed Target DHP as defined by Freeman, and naturally extends to provide algorithms for solving the Delayed Target DLP, the One-More DHP and One-More DLP, as studied by Koblitz and Menezes in the context of Jacobians of hyperelliptic curves of small genus. We also argue that for any group in which index calculus can be effectively applied, the above problems have a natural relationship, and will always be easier than the DLP. While practical only for very small n, our algorithm reduces the security provided by the elliptic curves defined over Fp2 and Fp4 proposed by Galbraith, Lin and Scott at EUROCRYPT 2009, should they be used in any protocol where a user can be made to act as a proxy Static DHP oracle, or if used in protocols whose security is related to any of the above problems