Learning Boolean Halfspaces with Small Weights from Membership Queries

We consider the problem of proper learning a Boolean Halfspace with integer weights $\{0,1,\ldots,t\}$ from membership queries only. The best known algorithm for this problem is an adaptive algorithm that asks $n^{O(t^5)}$ membership queries where the best lower bound for the number of membership queries is $n^t$ [Learning Threshold Functions with Small Weights Using Membership Queries. COLT 1999] In this paper we close this gap and give an adaptive proper learning algorithm with two rounds that asks $n^{O(t)}$ membership queries. We also give a non-adaptive proper learning algorithm that asks $n^{O(t^3)}$ membership queries

A Model for Optimizing Energy Investments and Policy Under Uncertainty with Application to Saudi Arabia

An energy producer must determine optimal energy investment strategies in order to maximize the value of its energy portfolio. Determining optimal investment strategies is challenging. One of the main challenges is the large uncertainty in many of the parameters involved in the optimization process. Existing large-scale energy models are mostly deterministic and thus have limited capability for assessing uncertainty. Modelers usually use scenario analysis to address model input uncertainty. In this research, I developed a probabilistic model for optimizing energy investments and policies from an energy producer’s perspective. The model uses a top-down approach to probabilistically forecast primary energy demand. Distributions rather than static values are used to model uncertainty in the input variables. The model can be applied to a country-level energy system. It maximizes the portfolio expected net present value (ENPV) while ensuring energy sustainability. The model was built in MSExcel® using the @RISK Palisade add-in, which is capable of modeling uncertain parameters and performing stochastic simulation optimization. The model was applied to Saudi Arabia to determine its optimum energy investment strategy, determine the value of investing in alternative energy sources, and compare deterministic and probabilistic modeling approaches. The model, given its assumptions and limitations, suggests that Saudi Arabia should keep its oil production capacity at 12.5 million barrels per day, especially in the short term. It also suggests that most of the future power-generation (electricity) demand in Saudi Arabia should be met using alternative-energy sources (nuclear, solar, and wind). Otherwise, large gas production is required to meet such demand. In addition, comparing probabilistic to deterministic model results shows that deterministic models may overestimate total portfolio ENPV and underestimate future investments needed to meet projected power demand. A primary contribution of this work is rigorously addressing uncertainty quantification in energy modeling. Building probabilistic energy models is one of the challenges facing the industry today. The model is also the first, to the best of my knowledge, that attempts to optimize Saudi Arabia’s energy portfolio using a probabilistic approach and addressing the value of investing in alternative energy sources

Financial Sector Reform and Its Impact on Investment and Economic Growth: An Econometric Approach

The financial sector is central to economic development as it serves the role of intermediary by mobilising savings and subsequently allocating credit for productive activities. However, in many developing countries including Pakistan, administered interest rate, domestic credit controls, high reserve requirements, use of captive banking system to finance large budgetary requirements of the government and controls on international capital inflows have remained the main features of the monetary policy. These repressive policies had their repercussions in the form of excess liquidity with the banking system, disintermediation of cash flows, segmentation of financial markets, underdeveloped money and capital markets, etc. [McKinnon (1973) and Shaw (1973)], therefore, argued that low interest rate ceilings unduly restrict the real flow of loanable funds, thus depressing the quantity of productive investment. Financial liberalisation, on the other hand, is defined as policy measures designed to deregulate certain operations of the financial system and transform its structure with a view to achieving a liberalised market oriented system with an appropriate regulatory framework. The financial sector reforms would lead to increase in loanable funds by attracting more household savings to bank deposits due to higher interest rates. This, in turn, would result in greater investment and faster economic growth.

Experimental and numerical analysis of the asymmetric flat rolling process of square section bars

This paper analyzed the asymmetric flat rolling process of square section bars by testing experiments and finite element simulation methods. The impacts of the rate of roll diameter, decrease in altitude, and rotational speeds of the rolls on the width of cross-section and the curl radii at the leaving point of deformation for the brass and aluminum bar materials were investigated. Furthermore, the asymmetric rolling process of square section bars was simulated using ABAQUS commercial software. A great convergence was demonstrated among the findings forecasted by the FEM simulation and the experimental findings. It was found that by increasing the rate of rolling diameter, the curl radius and the width of the bar cross-section at the exit have been increased, and the roll speed has a insignificant impact on the width and the curl radius of the rolled bar

Proton and Neutron Pairing Properties within a mixed volume-surface pairing force using SKI3-HFB Theory

This work aims at a systematic investigations of the pairing properties and Fermi properties from the proton drip-line to the neutron drip-line. In order to provide more accurate mass formula with skyrme SKI3 force, the global descriptive power of the SKI3-HFB model for pairing properties are made in this study. Systematic Skyrme SKI3-Hartree-Fock-Bogoliubov calculations with a mixed volume-surface pairing force are carried out to study the ground-state neutron and proton pairing gap, neutron and proton pairing energy and neutron and proton Fermi energy for about 2095 even-even nuclei ranging from $2\le{Z}\le110$ to $2\le{N}\le236$. The calculated results of neutron and proton pairing gap are compared with experimental data using the difference-point formulas $\Delta^{(3)}, \Delta^{(4)}$ and $\Delta^{(5)}$, and also compared with the neutron and proton pairing gap of Lipkin-Nogami model. It is shown that the Skyrme-SKI3 functional with the mixed volume-surface pairing force can be successfully used for describing the ground-state pairing and Fermi properties of the investigated nuclei, in particularly the neutron-rich nuclei and the exotic nuclei near the neutron drip-line. On the other hand, the calculated neutron and proton pairing gap are in good agreement with the available experimental values of the neutron and proton pairing gap of the difference-point formulas $\Delta^{(3)}, \Delta^{(4)}$ and $\Delta^{(5)}$ and with the data of Lipkin-Nogami model over the whole nuclear chart.Comment: 18 pages, 9 figure

Nuclear Shell Model Calculations on Positive and Negative Parity States in upper 0f7/2- Shell Nuclei

The excitation energies for both the positive and negative parities of  (90Sr,90Y,92Nb and 92Zr)  isotopes have been  calculated by employing modified surface delta interaction. A comparison between our results and the available experimental data to theoretical test  for shell model description in  isotopes  above. It was seen that the obtained theoretical results are in agreement with the experimental data for each of  the all isotopes under study . Keywords: Excitation energy , Modified surface delta interaction ,Shell model

Adaptive Indexing of Documents Using Genetic Algorithms and Relevance Feedback

مقدمة: في هذه الورقة، تم البحث في مشكلة استرجاع الوثائق الصحيحة التي تحقق رغبات المستخدم. الهدف الرئيسي في أنظمة استرجاع المعلومات هو استرداد جميع الوثائق ذات الصلة فقط. طرق العمل: تم استخدام الخوارزمية الجينية لتحقيق هذا الهدف. أوصاف المستندات تم تكييفها وتغييرها باستخدام الخوارزمية الجينية، اعتمادًا على الأحكام التي اطلقها المستخدم (والتي تم جمعها والاحتفاظ بها) حول اهمية المستندات بالنسبة له. الخوارزمية الجينية هي أداة قوية تعتمد على مبادئ الداروينية وتقنيات التطور للبحث في فضاءات البحث المعقدة. يسهل استخدام الخوارزمية الجينية تكييف فهارس المستندات. تم تنفيذ ثلاثة طرق في الانتخاب: نمذجة عجلة الروليت ، ونمذجة عجلة الروليت مع النخبة والنمذجة الشاملة التصادفية. يتم حساب دالة الصلاحية باستخدام معامل Jaccard الذي يقيس التقارب بين الاستعلام وفهرس المستند. الاستنتاجات: توجد بين الكلمات المفتاحية المستخدمة لوصف محتوى الوثائق اعتماديات إحصائية. من الصعب استيعاب هذه الاعتماديات في نظام الاسترجاع. يمكن للخوارزمية الجينية أن تأخذ في الاعتبار هذه الاعتماديات أثناء عملها. وفقًا لنظرية المخطط وفرضية حجر البناء [10] ، يتم نشر المخططات الأكثر صلاحية من جيل إلى جيل ، حيث يتم أخذ عينات منها وإعادة تجميعها وتحويلها وإعادة تشكيلها لتشكيل سلاسل ذات صلاحية أعلى. هناك جانب آخر يمكن أن تقدمه الخوارزمية الجينية ، وهو الاعتماد على التغذية الراجعة المقدمة من مستخدمي نظام الاسترجاع لتكييف أوصاف المستندات، وإنتاج مجموعة جديدة من الأوصاف الأقرب إلى حاجات المستخدمين. تم استخدام ثلاثة انواع من الانتخاب المتناسب مع الصلاحية ، وهي نمذجة عجلة الروليت ، ونمذجة عجلة الروليت ذات النخبة ، والنمذجة الشاملة التصادفية. أظهرت النتائج تفوق النوع الثالث على الأول والثاني.Background: In this paper, the problem of retrieving the correct documents that satisfy the user's concerns is investigated. The main aim in information retrieval systems is to retrieve all and only relevant documents. Materials and Methods: The genetic algorithm is utilized to adapt and change the documents indexes, depending on relevance judgments collected from users. Genetic algorithm is a powerful tool that depends on the Darwinian principles and evolution techniques to search complex spaces. The use of genetic algorithm facilitates the adaptation of documents indexes. Sampling operation is performed using roulette wheel, roulette wheel with elitism and stochastic universal sampling. The fitness function is computed using Jaccard's coefficient that measure the closeness between query and document index. Results: The results show that the new descriptions are more efficient and closer to the population of users that use the information retrieval system. In addition, the stochastic universal sampling gave the best results. Conclusion: The keywords used to describe the content of documents have statistical dependencies among them. It is difficult to accommodate these dependencies in retrieval system. Genetic algorithm can consider these dependencies during its action. According to schema theorem and building block hypothesis [10], the fittest schemata are propagated from generation to generation, where they are sampled, recombined, mutated and resampled to form strings of potentially higher worth. Another aspect genetic algorithm can offer, is the reliance on the feedback provided by users of the retrieval system to adapt documents descriptions and selections variations were experimented with roulette sampling, with elitism, and with produce new set of descriptions closer to the population of users' needs. Three fitness proportionate selection variations are used, roulette wheel sampling, roulette wheel with elitism and  stochastic universal sampling. The results have indicated the superiority of the third over the first two.&nbsp

Experimental investigation and statistical modelling for assessing the sliding wear of Futilized Filament Fabrication (FFF) fabricated parts

A significant historical enabler for the improvement of industrial goods has been the characterization of novel materials. For example, a large variety of polymeric materials are readily accessible to manufacture the appropriate items depending on the production method. Due to its capacity to produce components with complicated geometries without the need for tools or a human interface, fused filament fabrication (FFF) is acquiring a unique edge in the industrial sector. By adjusting process parameters at the right values, the qualities of FFF-built items may be enhanced since they rely heavily on these factors. Increasing the service life of functioning components requires taking wear resistance into account. Because of this, the current work concentrates on a thorough investigation to comprehend the impact of 3 crucial elements, including layer thickness, printing speed, also infill density, infill density, and the sliding wear of test specimens. A mechanism of wear is explained by utilizing microphotographs