Transaction Cost and the Small Stock Puzzle: The Impact of Outliers in the NYSE, 1970-2000

In this article we study the effect of transaction costs on asset prices. We examine the characteristics of the actual extreme performers (Outliers), their stock prices, and transactions cost and link them to firm size. The analyses is based on data from the COMPUSTAT tapes with valid data for the bid and ask prices and the CRSP samples of all firms listed in the NYSE, AMEX, and NASDAQ during the period 1970-2000. Once transaction costs are taken into account, no positive abnormal returns are found for small firms. Transaction costs account fully for both the abnormality and the recent size discountability.Outliers, Transaction Costs, Size discount, NYSE, AMEX, NASDAQ

Early wildfire detection by air quality sensors on unmanned aerial vehicles: Optimization and feasibility

“Millions of acres of forests are destroyed by wildfires every year, causing ecological, environmental, and economical losses. The recent wildfires in Australia and the Western U.S. smothered multiple states with more than fifty million acres charred by the blazes. The warmer and drier climate makes scientists expect increases in the severity and frequency of wildfires and the associated risks in the future. These inescapable crises highlight the urgent need for early detection and prevention of wildfires. This work proposed an energy management framework that integrated unmanned aerial vehicle (UAV) with air quality sensors for early wildfire detection and forest monitoring. An autonomous patrol solution that effectively detects wildfire events, while preserving the UAV battery for a larger area of coverage was developed. The UAV can send real-time data (e.g., sensor readings, thermal pictures, videos, etc) to nearby communications base stations (BSs) when a wildfire is detected. An optimization problem that minimized the total UAV’s consumed energy and satisfied a certain quality-of-service (QoS) data rate were formulated and solved. More specifically, this study optimized the flight track of a UAV and the transmit power between the UAV and BSs. Finally, selected simulation results that illustrate the advantages of the proposed model were proposed”--Abstract, page iii

Courses timetabling based on hill climbing algorithm

In addition to its monotonous nature and excessive time requirements, the manual school timetable scheduling often leads to more than one class being assigned to the same instructor, or more than one instructor being assigned to the same classroom during the same slot time, or even leads to exercise in intentional partialities in favor of a particular group of instructors. In this paper, an automated school timetable scheduling is presented to help overcome the traditional conflicts inherent in the manual scheduling approach. In this approach, hill climbing algorithms have been modified to transact hard and soft constraints. Soft constraints are not easy to be satisfied typically, but hard constraints are obligated. The implementation of this technique has been successfully experimented in different schools with various kinds of side constraints. Results show that the initial solution can be improved by 72% towards the optimal solution within the first 5 seconds and by 50% from the second iteration while the optimal solution will be achieved after 15 iterations ensuring that more than 50% of scientific courses will take place in the early slots time while more than 50% of non-scientific courses will take place during the later time's slots

Design, fabrication, characterization and aging studies of solar selective absorber surfaces

Tese de Doutoramento - Programa Doutoral em Física (MAP- fis)Esta tese tem como objetivo o desenvolvimento de revestimentos para absorção seletiva da radiação solar, que tenham um elevado coeficiente de absorção solar (α) (> 95%), baixa emissividade (ε) (<12% a 400 ºC), e com elevada estabilidade térmica, acima de 400 ° C ao ar e acima de 600 ºC em vácuo, de modo a que possa ser usado em sistemas de concentração da radiação solar (CSP) que utilizem temperaturas elevadas. Os revestimentos são multicamadas, que têm quatro a cinco camadas, sendo as duas primeiras, uma barreira de difusão e um refletor de radiação infravermelha, tungsténio. As restantes são constituídas por uma estrutura de dupla camada para absorção da radiação solar e uma camada antirefletora. Para a configuração das camadas de absorção, foram utilizadas três soluções diferentes. As duas primeiras soluções baseiam-se em camadas de nitreto / oxinitreto de metais de transição, nomeadamente a partir de crómio (CrAlSiNx/CrAlSiNxOy) e tungsténio (WsiAlNx/WSiAlNxOy). A terceira solução é baseada em compósitos cerâmico-metal de AlSiOx:W. Camadas individuais das diferentes soluções foram depositadas em substratos de vidro, aço inoxidável (SS) e silício (Si) para estudar a composição química, estrutura, propriedades ópticas e mecânicas. Os espectros de transmitância e reflectância das camadas individuais, depositados em substratos de vidro, foram simulados com o software SCOUT, de modo a calcular a respetiva função dielétrica, as constantes ópticas espectrais e espessuras. As multicamadas foram desenhadas utilizando as constantes ópticas das camadas individuais, utilizando também o software SCOUT. Utilizando os resultados das simulações, as multicamadas foram depositadas em substratos de aço inoxidável utilizando a técnica de pulverização catódica por magnetrão e o desempenho dos revestimentos foi verificado por meio da sua absorção solar, da emissividade e do seu comportamento quando sujeitos a tratamentos térmicos ao ar e em vácuo. Diversas técnicas de caracterização foram utilizadas para estudar os revestimentos, nomeadamente por microscopia eletrónica de varrimento (SEM), espectrometria de retrodispersão de Rutherford (RBS), difração de raios X (DRX), espectroscopia de infravermelho com transformada de Fourier (FTIR), espectroscopia de fotoeletrões de raios-X (XPS), espectroscopia de raios-X por dispersão em energia (EDS), análise de detecção de recuo elástico por tempo de voo (TOF-ERDA), espectroscopia Raman e espectroscopia UV-VIS-NIR. Os revestimentos multicamada apresentados nesta tese mostraram boa estabilidade térmica e resistência à oxidação após o tratamento térmico em vácuo a 600 ºC ou 580 ºC e tratamento térmico ao ar a 400 ºC ou 450 ºC. A solução baseada na estrutura WSiAlNx/WSiAlOyNx apresentou os melhores resultados, em termos de estabilidade térmica, resistência à oxidação e coeficiente de absorção solar, enquanto a baseada em CrAlSiNx/CrAlSiNxOy apresentou os valores mais baixos de emissividade à temperatura de 400 ºC. As alterações no coeficiente de absorção solar (αsol) e na emissividade (ε) são insignificantes na maioria dos casos. Em alguns casos, só foram reveladas pequenas mudanças nas curvas de refletância após o primeiro passo de tratamento térmico, não aparecendo alterações nos passos subsequentes. No caso dos revestimentos baseados em CrAlSiNx / CrAlSiNxOy, após o tratamento térmico em vácuo a 600 ºC, verificou-se que ocorreu a difusão de átomos de tungsténio da camada de W para o substrato de aço inoxidável. Assim, foi introduzida uma camada de barreira de CrAlSiNx entre a camada de tungsténio e o substrato de aço e fetuado o respetivo estudo, tendo-se verificado a não ocorrência da difusão do W.This thesis has the objective to develop solar selective absorber coatings having simultaneously high solar absorptance (α) (>95%) and low emissivity (ε) (<12% at 400 ºC) together with high thermal stability above 400°C in air and above 600 ºC in vacuum, which could be used in the concentrated solar power (CSP) or in other high temperature applications. The coatings are multilayer stacks, that have four to five layers, being the first two, a barrier layer and a back-reflector tungsten layer. The remaining layers comprise a double film structure for phase interference finished by an antireflection layer. For the double absorption layer configuration, three different approaches have been used. The first two are based on transition metal nitride/oxynitride layers, namely from chromium as (CrAlSiNx/CrAlSiNxOy) and from tungsten as (WSiAlNx/WSiAlNxOy). Whereas, the third one is based on (AlSiOx:W) cermets. The single layers of each approach were deposited on glass, stainless-steel (SS) and silicon (Si) substrates to study their chemical composition, structure, optical and mechanical properties. The transmittance (T) and the reflectance (R) spectra of single thin layers, deposited on glass substrates, were modelled with the help of SCOUT software and the spectral optical constants and thicknesses were calculated. The multilayer designs were performed using the optical constants of the single layers and conducted with SCOUT software. The final multilayer stacks were deposited on stainless-steel substrates using DC magnetron sputtering technique and the functionality of the absorbers optical stacks was verified through solar absorptance, emissivity and accelerated thermal ageing treatments. All tandems and their individual layers were characterized by Scanning Electron Microscopy (SEM), Rutherford Backscattering Spectrometry (RBS), X-ray diffraction (XRD), Fourier-transform Infrared Spectroscopy (FTIR), X-Ray Photoelectron Spectroscopy (XPS), Energy Dispersive X-ray Spectroscopy (EDS), Time of flight Elastic Recoil Detection Analysis (TOF-ERDA), Raman spectroscopy and UV–VIS–IR spectroscopy. The absorber tandems presented in this thesis showed good thermal stability and oxidation resistance after vacuum annealing at 600 ºC or 580 ºC and air annealing at 400 ºC or 450 ºC. The approach based on WSiAlNx/WSiAlOyNx tandem showed the best thermal stability, oxidation resistance and it has higher solar absorbance, αsol, while the CrAlSiNx/ CrAlSiNxOy shows the lowest thermal emittance at the temperature (400 ºC). The variations in the solar absorptance (αsol) and the thermal emittance (ε) are negligible in most cases. In some cases, small variations in the reflectance curves after the first step of annealing were observed. After the annealing in vacuum at 600 ºC, tungsten diffusion from the back-reflection layer towards the stainless-steel substrate was found in the tandem based on CrAlSiNx/ CrAlSiNxOy. Thus, a CrAlSiNx barrier layer with higher nitrogen N content was included between the stainlesssteel substrate and tungsten. The influence of that barrier layer upon the W diffusion was also studied.Financial support of FCT, POCI and PORL operational programs through the project POCI- 01-0145-FEDER-016907 (PTDC/CTM-ENE/2882/2014), co-financed by European community fund FEDER

Effect of Silica Powder on the Bond between Building Stones and Pumice Concrete

The Concrete Backed Stone (CBS) masonry structures are common in many countries in the Middle East. The weak bond and heavyweight are two main problems facing such masonry structures. In this research, Pumice Lightweight Aggregate Concrete (PLWAC) containing silica powder addition is used in backing building stones. The main objective of this research is to investigate the effect of using silica powder addition on the bond strength between building stones and the PLWAC. An experimental program is conducted to investigate the bond strength by applying a direct shear load to the concrete-stone interface. The study investigated the effect of some parameters such as the silica content, the stone surface roughness, and the concrete strength on the bond between lightweight concrete and building stones. The stone roughness comprised specimens of saw-cut and grooved stones with different groove depths. Tests showed that the bond and the compressive strength of the PLWAC increased by increasing the silica content up to 15 percent, where they start to decline. The increase in bond strength corresponding to 10 and 15 percent silica content was 14 and 33 percent, respectively. Increasing the stone roughness by about 50 percent of the saw-cut surface area provided a full bond between the building stones and their backing concrete. Furthermore, the study offered a formula that estimates the bond strength and agrees well with test results. Doi: 10.28991/cej-2021-03091656 Full Text: PD

Prediction of Compressive Strength of Fibrous Composites Using Two Different Approaches

This paper presents two different approaches to predict the compressive strength of fibrous composites using three-dimensional analysis. These approaches are based on the optimization of compressive stress resulting from the relationship between the compressive stress of the fibrous composite and the shear strength of the matrix material. The first approach is an estimation of compressive strength based on the actual initial misalignment of fibers in the rotated plane. The second approach is an approximation of compressive strength in accordance with the components of the initial fiber misalignment relative to the global axes of the fibrous composite material. The initial fiber misalignment is defined as a curve in the form of a cosine function that has components on the two planes containing the longitudinal axis and defined by initial misalignment angles. Equilibrium equations are then derived for an infinitesimal element along the axis of the fibers using the total potential energy principle. Maximum compressive strength is calculated using the corresponding shear stresses and shear deformations in the matrix, since shear is the dominant mode of failure. The compressive strength corresponding to the shear mode is found to be related to the tangent shear modulus of a fibrous composite material. The two different approaches are used to study the following composites: Carbon/epoxy XAS/914C saturated and dry, Carbon/Peek AS4/PEEK (APC-2), AS4/E7K8, Glass-Vinyl Ester, Glass-Polyester and unidirectional HTS40/977-2. The results obtained in this paper are found to agree well with experimental results and theoretical results available in literature

The Possibility of Accounting Information Systems to Support the Standard costs: Analytical study Insurance Sector – Jordan

This study examines the evaluation of the relationship between accounting information systems &amp; standard costs, researchers have used a sample of 27 insurance companies belonging to the insurance sector listed on the Amman Stock Exchange Securities, The study discussed at several major themes are: The standard cost system, as partial of the cost accounting information system and has a strong relationship with the budgeting system. Evaluation of performance using a standard cost system as a method of cost control. Standard costing system remains appropriate with the new business environment. The study found many of the results was the most important focusing on objective accounting information system and the possibility to support the standard costs, so as to ensure make true decisions or correct decisions taken previously, this would preserve the continuity of the enterprise and increases the useful life or its product age, and guarantee them a competitive advantage in the business environment. Keywords: Insurance Company, AIS (Accounting Information Systems), Standard Cost, ASE (Amman Security Exchange), Insurance Sector

Early Wildfire Detection using Uavs Integrated with Air Quality and Lidar Sensors

Every year, wildfires burn out countless hectares of lands, resulting in ecological, environmental, and economic damage. This paper presents an energy management system that consists of an unmanned aerial vehicle (UAV) equipped with air quality and light detection and ranging (LiDAR) sensors for monitoring forests and recognizing flames early. We develop a novel approach for autonomous patrolling system. This approach has the advantage of effectively detecting wildfire incidents, while optimizing the energy consumption of the UAV\u27s battery to cover large areas. When a wildfire is detected, the UAV is able to transmit real-time data, such as sensor readings and LiDAR data, to the nearby communication tower. We formulate an optimization problem that minimizes the overall UAV\u27s energy consumption due to patrolling. Based on the pollutant dispersion mode, we propose a novel UAV patrolling solution based on genetic algorithm with the goal of maximizing the patrolling coverage of the UAV taking into account the UAV\u27s battery constraints. More specifically, we optimize the UAV\u27s flight path using a plume dispersion model to find the concentration of common gases of wildfire. Finally, simulations are presented to show the efficiency and validity of the solution

Artificial Intelligence Models for Scheduling Big Data Services on the Cloud

The widespread adoption of Internet of Things (IoT) applications in many critical sectors (e.g., healthcare, unmanned autonomous systems, etc.) and the huge volumes of data that are being generated from such applications have led to an unprecedented reliance on the cloud computing platform to store and process these data. Moreover, cloud providers tend to receive massive waves of demands on their storage and computing resources. To help providers deal with such demands without sacrificing performance, the concept of cloud automation had recently arisen to improve the performance and reduce the manual efforts related to the management of cloud computing workloads. However, several challenges have to be taken into consideration in order to guarantee an optimal performance for big data storage and analytics in cloud computing environments. In this context, we propose in this thesis a smart scheduling model as an automated big data task scheduling approach in cloud computing environments. Our scheduling model combines Deep Reinforcement Learning (DRL), Federated Learning (FL), and Transfer Learning (TL) to automatically predict the IoT devices to which each incoming big data task should be scheduled to as to improve the performance and reduce the execution cost. Furthermore, we solve the long execution time and data shortage problems by introducing a FL-based solution that also ensures privacy-preserving and reduces training and data complexity. The motivation of this thesis stems from four main observations/research gaps that we have drawn through our literature reviews and/or experiments, which are: (1) most of the existing cloud-based scheduling solutions consider the scheduling problem only from the tasks priority viewpoint, which leads to increase the amounts of wasted resources in case of malicious or compromised IoT devices; (2) the existing scheduling solutions in the domain of cloud and edge computing are still ineffective in making real-time decisions concerning the resource allocation and management in cloud systems; (3) it is quite difficult to schedule tasks or learning models from servers in areas that are far from the objects and IoT devices, which entails significant delay and response time for the process of transmitting data; and (4) none of the existing scheduling solutions has yet addressed the issue of dynamic task scheduling automation in complex and large-scale edge computing settings. In this thesis, we address the scheduling challenges related to the cloud and edge computing environment. To this end, we argue that trust should be an integral part of the decision-making process and therefore design a trust establishment mechanism between the edge server and IoT devices. The trust mechanism model aims to detect those IoT devices that over-utilize or under-utilize their resources. Thereafter, we design a smart scheduling algorithm to automate the process of scheduling large-scale workloads onto edge cloud computing resources while taking into account the trust scores, task waiting time, and energy levels of the IoT devices to make appropriate scheduling decisions. Finally, we apply our scheduling strategy in the healthcare domain to investigate its applicability in a real-world scenario (COVID-19)