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

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

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

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

A New Mechanical Analysis of a Crankshaft-connecting Rod Dynamics Using Lagrange’s Trigonometric Identities

The main objective of this study was to conduct a new and simple but accurate analysis of the dynamics of a crankshaft-connecting rod system based on Lagrange’s trigonometric identities. Actual and equivalent connecting rod mass approximations of single- and multi-cylinder reciprocating engines were studied. Several examples were studied to demonstrate the dynamics of the system. Lagrange’s trigonometric identities were used to simplify the model, while MATLAB was used to obtain the results. For both the proposed reduced model and the full model, the resultant forces and torques of an actual and an equivalent connecting rod mass were compared. The results showed that the proposed reduced model gives force and torque results that match the results of the full model very well. It was shown that the largest torque imbalance resultant on the crankshaft was exerted by the two-cylinder engine. In addition, it was shown that the largest external forces resultant acting in the x-direction was exerted by the one-cylinder engine. The results also revealed that the resultant of external forces acting in the y-direction was zero for multi-cylinder engines. The relative error, which mainly occurred at the points of maximum force and torque, ranged from about 1% to about 15%

Spectroscopy Characterization of Ethylene Vinyl Acetate Degradation by Different Kinds of Accelerated Aging

يقدم البحث رؤية حول التشوه الحاصل في التركيب الكيمياوي للبوليمر المشترك المتحلل  اثلين فنيل الخلات EVA وذلك بحسب تغير نسبة قيم ثوابت المعدل المستحصلة من منحنيات الحركية الطيفية للعينات المتحللة. اذ تم تحديد  تضبيط رسم منحنيات الحركية الطيفية للفلورة ولمجالين مميزين من الاطوال الموجية لشدات الفلورة. حيث أظهرت الاطوال الموجية القصيرة (320-400 nm) تداخلا في الاطياف, بينما عند الاطوال الموجية الطويلة (400-800 nm) بدت الاطياف منتظمة وحسب أزمنة التعتيق المعجل. أن النسبة لثابت معدل سرعة التفاعل  عند الاطوال الموجية الطويلة الى ثابت معدل سرعة التفاعل للاطوال الموجية القصيرة هو المعيار لدرجة التشوه في البنية الكيمياوية. حيث يعتمد المعامل المولاري الخارجي على البنية الكيمياوية. من خلال قياس الامتصاصية, تم تصنيف نماذج EVA الى مجموعتين. اذ ان وجود اضافات Cyasorb هي النقطة الرئيسية في التصنيف. تم دراسة تأثير الأنواع المختلفة للتعتيق المعجل وهي, تسخين جاف عند 115 ℃و تسخين رطب عند رطوبة نسبية مقدارها 85% ودرجة حرارة 85 ℃ وتعتيق التشعيع بالاشعة فوق البنفسجية عند درجة حرارة 65 ℃ وعند ازمنة تعتيق مختلفة لكل مجموعة. وقد تم مناقشة نتائج اطياف الامتصاص والفلورة للعينات. اجمالا, فان اضافة Cyasorb تسبب تشوه اعلى في التركيب الكيمياوي عند تحلل. EVA  أن العامل الاكثر تأثيرا هو التعتيق الرطب بينما الاقل يحصل بواسطة التشعيع بالاشعة فوق البنفسجية. بينما تغير التركيب الكيمياوي الاكبر يحدث للعينة الخالية من اضافة Cyasorb , حيث ينتج من التعتيق الرطب أما التغير الاقل فينتج بواسطة التسخين الجاف.            This paper presents a sight about the chemical structure deformation of poly (ethylene-co-vinyl acetate) (EVA) samples according to the change ratio of rate constant values. Spectroscopy kinetics fluorescence curves are fitted for two characteristic wavelength domains of fluorescent intensities. The short wavelengths (320-400 nm) domain show spectra overlapping, while at long wavelengths (400-800 nm) domain spectra are arranged in regular for each specific accelerated aging time. The ratio of kinetics rate constant at long wavelengths to kinetics rate constant of short wavelengths is the criterion of the degree chemical structure deformation. Molar extrinsic coefficient relies on the chemical structure change. Through absorbance measurement, EVA samples have been classified into two groups. Presence of Cyasorb additive is the key point of the ranking. The effect of three different accelerated aging of dry (115 oC), damp (85% moisture, 85 oC), and irradiated (UV, 65 oC) aging have been considered for two samples of each group over different aging time. Spectroscopy of absorbance and fluorescent for aged samples have been discussed. In general, Cyasorb adding causes higher chemical structure deformation for the EVA sample. The most effective factor is the damp aging and the less one is the UV irradiation aging, while the biggest chemical structure change of Cyasorb-free sample is produced by damp aging and the less by dry heat.  &nbsp