Slave spin cluster mean field theory away from half-filling: Application to the Hubbard and the extended Hubbard Model

A new slave-spin representation of fermion operators has recently been proposed for the half-filled Hubbard model. We show that with the addition of a gauge variable, the formalism can be extended to finite doping. The resulting spin problem can be solved using the cluster mean-field approximation. This approximation takes short-range correlations into account by exact diagonalization on the cluster, whereas long-range correlations beyond the size of clusters are treated at the mean-field level. In the limit where the cluster has only one site and the interaction strength $U$ is infinite, this approach reduces to the Gutzwiller approximation. There are some qualitative differences when the size of the cluster is finite. We first compute the critical $U$ for the Mott transition as a function of a frustrating second-neighbor interaction on lattices relevant for various correlated systems, namely the cobaltites, the layered organic superconductors and the high-temperature superconductors. For the triangular lattice, we also study the extended Hubbard model with nearest-neighbor repulsion. In additionto a uniform metallic state, we find a $\sqrt(3) \times \sqrt(3)$ charge density wave in a broad doping regime, including commensurate ones. We find that in the large $U$ limit, intersite Coulomb repulsion $V$ strongly suppresses the single-particle weight of the metallic state.Comment: 10 pages, 11 figures, submitted to PR

Proposed business plan for pilot farmer organizations: Extended project on Farmer Managed Irrigated Agriculture in LBOD Project Area of Sindh Province

Farmers' associations / Farmer managed irrigation systems / Irrigation programs / Irrigation management / Drainage / Economic aspects / Income / Operating costs / Maintenance costs / Conflict

An Assessment of Air Quality in and around Gwagwalada Abattoir, Gwagwalada, Abuja, Fct.

This work attempted an assessment of air quality in and around Gwagwalada abattoir. Air samples were collected from six points around the abattoir and recorded insitu for analysis.  The following parameters were investigated; Particulate Matter (PM), Carbon monoxide (CO), Sulphur dioxide (SO2), Nitrogen dioxide (NO2), Ammonia (NH3), Chlorine (CL2) and Hydrogen cyanide. The statistical test employed was the Student t-test in verifying the hypothesis. Based on the data collected and the analysis made, it was observed that the mean values of the parameters varied from points to points and at different time of the day. Also, the mean values of the parameters were compared with the FEPA recommended limits, and it was observed that Sulphur dioxide (SO2), Nitrogen dioxide (NO2) and Particulate matter were above the FEPA recommended limit. While Carbon monoxide (CO), Hydrogen cyanide (HCN) and Ammonia (NH3) are still below the standard limit. Air Quality Index shows that Sulphur dioxide (SO2), and  Nitrogen dioxide (NO2 have very poor quality index Recommendations include; relocation of abattoir to an area far from residences, inspection of abattoir process by professionals in related fields, proper waste management systems should be made. Keywords: Air, Quality, AQI, Abattoir, pollution, and Gwagwalad

Macro-micro feedback links of water management in South Africa : CGE analyses of selected policy regimes

The pressure on an already stressed water situation in South Africa is predicted to increase significantly under climate change, plans for large industrial expansion, observed rapid urbanization, and government programs to provide access to water to millions of previously excluded people. The present study employed a general equilibrium approach to examine the economy-wide impacts of selected macro and water related policy reforms on water use and allocation, rural livelihoods, and the economy at large. The analyses reveal that implicit crop-level water quotas reduce the amount of irrigated land allocated to higher-value horticultural crops and create higher shadow rents for production of lower-value, water-intensive field crops, such as sugarcane and fodder. Accordingly, liberalizing local water allocation in irrigation agriculture is found to work in favor of higher-value crops, and expand agricultural production and exports and farm employment. Allowing for water trade between irrigation and non-agricultural uses fueled by higher competition for water from industrial expansion and urbanization leads to greater water shadow prices for irrigation water with reduced income and employment benefits to rural households and higher gains for non-agricultural households. The analyses show difficult tradeoffs between general economic gains and higher water prices, making irrigation subsidies difficult to justify.Water Supply and Sanitation Governance and Institutions,Town Water Supply and Sanitation,Water Supply and Systems,Water and Industry,Water Conservation

The use of fuzzy real option valuation method to rank Giga Investment Projects on Iran's natural gas reserves

Giga investments are exposed to numerous systematic and unsystematic (or specific) risks that significantly influence their feasibility and value. In addition to the conventional issues and complexities in evaluating investment projects, factors such as long construction time, high amount of capital required and irreversibility of investment, increase uncertainty of cash flows in these types of projects. As a consequence, decision makers are usually not satisfied with the results of the most popular valuation methodology – discounted cash flow analysis – in valuation of Giga investments. The most promising methodology of valuing flexibility in such investment projects is the real options valuation which quantifies the value of embedded flexibilities through option pricing techniques.In this paper, fuzzy real options valuation techniques are used to rank Giga project proposals faced in Iran's gas industry. To this end, different scenarios of project payoff and future uncertainties are quantified, using fuzzy numbers based on findings from earlier real option valuation methods.Keywords: Giga Investment, Fuzzy Pay Off, Real options valuation, Natural Gas, Ira

Combining ability analysis for seed yield and its components in sesame

    Sesame (Sesamum indicum L.) experiments, were carried out in central Sudan during the rainy season of 2009 at two locations (Abu Naama and Sinnar). The hybridization plan consisted of seven male and seven female parents giving 49 crosses following line x tester arrangement. Treatments were arranged in a randomized complete block design with three replicates. The crosses and their parents were sown on the 7th of July for all the experiments at both locations. The traits measured were days to 50% flowering, days to maturity, plant height, number of capsules per plant, number of seeds per capsule, capsule length, 1000-seed weight and seed yield. Analysis of variance revealed that genetic variability was highly significant for all the characters studied at both locations and across them. Combining ability analysis showed that additive gene effects were important for inheritance of days to 50% flowering, plant height, number of capsules/plant, number of seeds per capsule, capsule length, 1000-seed weight, days to maturity and seed yield, whereas non-additive gene effects were important for number of seeds/capsule, indicating that the inheritance of this trait is due to specific combining ability (SCA). Combining ability analysis showed that parents, L7, L5, T2, T5 and T6 were good combiners for high seed yield as well as for most of the other traits measured in this study. Assessment of SCA effects for seed yield at Abu-Namma revealed that hybrid T4 x L4 had a maximum positive SCA effect and a high per se performance followed by T2 x L2, T5 x L5 and T6 x L3, while at Sinnar T6 x L6 had the highest positive SCA effects followed by T6 xL3, T1 x L5 and T2 x L6. However T6 x L3, T1 x L5, T4 x L2 and T2 x L1 exhibited the highest SCA effects across sites. The present study suggested hybrids T6 x L3, T1 x L5 and T4 x L2 to be tested in multi-location trials for commercial utilization, while, parents L7, L5, T2 and T6 can be used in recurrent selection.    أجريت هذه التجارب في السودان أثناء الفصل الممطر عام 2009 في أبو نعامة وسنار بإتباع تحليل سلالة x مختبر line x tester analysis)) والذي شمل سبعة آباء ذكورmale parents)) وسبعة أباء اناث  (female parents) معطية 49 هجيناً. أستخدم تصميم القطاعات العشوائية الكاملة بثلاث مكررات. زرعت التجارب في يوم 7 يوليو 2009 في كلا الموقعين. الصفات التي تمت دراستها شملت عدد الأيام حتى 50% إزهار، عدد الأيام حتى النضج، طول النبات، عدد الكبسولات في النبات، عدد البذور في الكبسولة، طول الكبسولة، وزن 1000 بذرة وإنتاجية البذور. أظهر تحليل التباين وجود فروق معنوية لكل الصفات المدروسة في الموقعين. أظهر تحليل القدرة علي التالف أن تأثيرات الفعل الإضافي للجين كانت أهم لتوريث صفات عدد الأيام حتى 50% إزهار، طول النبات، ارتفاع أول كبسولة، ارتفاع أول فرع، عدد الفروع في النبات، عدد الكبسولات في النبات، طول الكبسولة، عدد الأيام حتى النضج، وزن 1000 بذرة و إنتاجية البذور كما كانت تأثيرات الفعل الجيني غير الإضافي مهمة في توريث صفة عدد البذور في الكبسولة وهذه النتيجة تشير بان السيادة وتفاعلات التفوق تتحكم في تلك الصفة. أظهرت تأثيرات القدرة العامة للاتحاد إن الآباء L7  T5, T2, L5,و  T6كانت الأفضل قدرة على الاتحاد لإنتاج البذور بالإضافة لأغلب الصفات الأخرى في التحليل المشترك. الهجن التي أظهرت أعلى قوة  هجين في أبونعامة T5 x L5, T2 x L2, T4 x L4 وT6 x L3 ، بينما في سنار T6 x L6, T6 x L3, T2 x L6 و T1 x L5وعبر الموقعين  T6 x L3, T1 x L5, ,T4xL2 وT2 x L1. وجد أن هناك ارتباطاً موجباً لإنتاجية البذور لكل من وزن 1000 بذرة ، عدد الكبسولات في النبات وعدد الأيام حتى النضج. اقترحت الدراسة الحالية إن الهجنT1 x L5, T6 x L3  وT6 x L7 لإنتاج البذور أما الآباء T4، T1 ، L6و T6  فيمكن استخدامهم في التهجين الرجع

Zero Temperature Insulator-Metal Transition in Doped Manganites

We study the transition at T=0 from a ferromagnetic insulating to a ferromagnetic metallic phase in manganites as a function of hole doping using an effective low-energy model Hamiltonian proposed by us recently. The model incorporates the quantum nature of the dynamic Jahn-Teller(JT) phonons strongly coupled to orbitally degenerate electrons as well as strong Coulomb correlation effects and leads naturally to the coexistence of localized (JT polaronic) and band-like electronic states. We study the insulator-metal transition as a function of doping as well as of the correlation strength U and JT gain in energy E_{JT}, and find, for realistic values of parameters, a ground state phase diagram in agreement with experiments. We also discuss how several other features of manganites as well as differences in behaviour among manganites can be understood in terms of our model.Comment: To be published in Europhysics Letter

The divider set of explicit parametric geometry

In this paper we describe a novel concept for classification of complex parametric geometry based on the concept of the Divider Set. The Divider Set is an alternative concept to maximal disks, Voronoi sets and cut loci. The Divider Set is based on a formal definition relating to topology and differential geometry. In this paper firstly we discuss the formal definition of the Divider Set for complex 3-dimensional geometry. This is then followed by the introduction of a computationally feasible algorithm for computing the Divider Set for geometry which can be defined in explicit parametric form. Thus, an explicit solution form taking advantage of the special form of the parametric geometry is presented. We also show how the Divider Set can be computed for various complex parametric geometry by means of illustrating our concept through a number of example

Coordinated Generation and Transmission Maintenance Scheduling Considering Network Constraints via GGDF and ODF

This paper proposes a coordinated generation and transmission maintenance scheduling by incorporating network constraints. The main advantage of the proposed approach is that maintenance is scheduled at the optimal period of the lowest possible operating cost while satisfying all the specified constraints. In this approach, sensitivity factors (GGDFs and ODFs) which are based on DC approximation are applied to calculate the line flows in normal and maintenance conditions. They are applied due to their simplicity, linearity, physical comprehension and rapidity of computation. To simulate the effect of network constraint on maintenance schedule and operating cost, several cases are studied with and without transmission limit constraints. To ensure the accuracy of these sensitivity factors, power flows on each line are compared with the one obtained from a PSSE simulator. The result shows that generators and transmission lines are scheduled at periods that satisfy the transmission capacity limit