The Smooth-Lasso and other ℓ1+ℓ2\ell_1+\ell_2-penalized methods

We consider a linear regression problem in a high dimensional setting where the number of covariates $p$ can be much larger than the sample size $n$. In such a situation, one often assumes sparsity of the regression vector, \textit i.e., the regression vector contains many zero components. We propose a Lasso-type estimator $\hat{\beta}^{Quad}$ (where '$Quad$' stands for quadratic) which is based on two penalty terms. The first one is the $\ell_1$ norm of the regression coefficients used to exploit the sparsity of the regression as done by the Lasso estimator, whereas the second is a quadratic penalty term introduced to capture some additional information on the setting of the problem. We detail two special cases: the Elastic-Net $\hat{\beta}^{EN}$, which deals with sparse problems where correlations between variables may exist; and the Smooth-Lasso $\hat{\beta}^{SL}$, which responds to sparse problems where successive regression coefficients are known to vary slowly (in some situations, this can also be interpreted in terms of correlations between successive variables). From a theoretical point of view, we establish variable selection consistency results and show that $\hat{\beta}^{Quad}$ achieves a Sparsity Inequality, \textit i.e., a bound in terms of the number of non-zero components of the 'true' regression vector. These results are provided under a weaker assumption on the Gram matrix than the one used by the Lasso. In some situations this guarantees a significant improvement over the Lasso. Furthermore, a simulation study is conducted and shows that the S-Lasso $\hat{\beta}^{SL}$ performs better than known methods as the Lasso, the Elastic-Net $\hat{\beta}^{EN}$, and the Fused-Lasso with respect to the estimation accuracy. This is especially the case when the regression vector is 'smooth', \textit i.e., when the variations between successive coefficients of the unknown parameter of the regression are small. The study also reveals that the theoretical calibration of the tuning parameters and the one based on 10 fold cross validation imply two S-Lasso solutions with close performance

Silicon nano wires solar cell

Improving the optical absorption capability of solar cells\u27 materials is a crucial factor in increasing their power conversion efficiency. To this end, the absorption can be enhanced by minimizing the reflection and the transmission out from the absorbing layer. While the reflection can be minimized using an antireflection coating, the transmission can be minimized by exploiting a light- trapping mechanism. In this thesis, the Si nanowires have been utilized to enhance the absorption and photocurrent without the need for antireflection coating, and provide high field localization, which in turn enhances the overall efficiency of the solar cell. Vertically orientated single crystalline silicon nanowire (SiNW) arrays with controlled diameters have been fabricated via a metal-assisted chemical etching (MACE) method. The diameter of the fabricated nanowires is controlled by simply varying the etching time in HF/H2O2 solution. The fabricated SiNWs have diameters ranging from 117 to 650 nm and length from 8 to 18 μm. The optical measurements show a significant difference in the reflectance/absorption of the SiNWs with different diameters, where the reflectance increases with increasing the diameter of the SiNWs. The optical absorption also has been measured at different incident light angle to determine the best angle for absorption. The best absorption angle for different diameters was 10o.The SiNWs showed significant photoluminescence (PL) emission spectra with peaks lying between 380 and 670 nm. The PL intensity increases as the diameter increases and shows red shift for peaks at ~ 670 nm. The increase or decrease of reflectivity is coincident with PL intensity at wavelength ~ 660 nm. The x-ray diffraction (XRD) patterns and high-resolution transmission electron microscope (HR-TEM) confirm the high crystallinity of the fabricated SiNWs. In addition, the Raman spectra showed a shift in the first order transverse (1TO) band toward lower frequencies compared to that usually seen for c-Si. The current-voltage characteristics have also been investigated using photoelectrochemical cell. The measurements have been done in two electrolytes; 10% HF 10% and hydrobromic acid (40%) and bromine (3%). The measurements have been done for the fabricated Si nanowires with different diameters under dark and illumination conditions. The resulted photocurrent decreases with increasing the diameter of SiNWs, which has been explained based on the Debye length of SiNWs. Full wave electromagnetic analysis has been performed using finite difference time domain simulations (FDTD) to confirm the effect of change of diameter on the optical properties of the nanowires. The simulation results show good agreement with the experimental findings for the SiNWs of different diameters. Also, the simulation has been done for different incident light angles to investigate the best incident angle that results in the highest absorption and minimum reflection

Design and Implementation of an ADCS for a CubeSat

The hardware implementation of the attitude determination process of the Attitude Determination Control Subsystem (ADCS) for CubeSat is presented in this paper. The process of determining attitude involves combining data from several sensors that monitor internal or external references. ADCS has four primary subsystems; the sensor system, the actuator system, the controller, and the interface. The proposed ADCS is based on implementing the controller and sensor subsystems to monitor attitude determination. The STM32F405 microcontroller is used on the board as the main controller. External circuits are designed on the board to be compatible with the microcontroller and ADCS functions. The supplied circuit feeds the board from the voltage supplied by six panels of solar cells. The step-down feeding board circuit and the step-down STM feeding circuit are designed to create a suitable step-down supply voltage. Two oscillators are designed, which are needed in the STM32F405 microcontroller. The three intended H-bridge drives are implemented for use with brush motors. A joint action group (J-Tag) is connected to debug the device. The ADCS board\u27s sensors subsystem included a magnetometer, temperature, and gyroscope sensors. The ADCS board circuits are simulated using Altium and fabricated On-Board Circuit (OBC) in small dimensions of 10×9.7 cm^2

Design and Implementation of an ADCS for a CubeSat

The hardware implementation of the attitude determination process of the Attitude Determination Control Subsystem (ADCS) for CubeSat is presented in this paper. The process of determining attitude involves combining data from several sensors that monitor internal or external references. ADCS has four primary subsystems; the sensor system, the actuator system, the controller, and the interface. The proposed ADCS is based on implementing the controller and sensor subsystems to monitor attitude determination. The STM32F405 microcontroller is used on the board as the main controller. External circuits are designed on the board to be compatible with the microcontroller and ADCS functions. The supplied circuit feeds the board from the voltage supplied by six panels of solar cells. The step-down feeding board circuit and the step-down STM feeding circuit are designed to create a suitable step-down supply voltage. Two oscillators are designed, which are needed in the STM32F405 microcontroller. The three intended H-bridge drives are implemented for use with brush motors. A joint action group (J-Tag) is connected to debug the device. The ADCS board\u27s sensors subsystem included a magnetometer, temperature, and gyroscope sensors. The ADCS board circuits are simulated using Altium and fabricated On-Board Circuit (OBC) in small dimensions of 10×9.7 cm^2

Rethinking Microfinance in a Dual Financial System: An Agent-based Simulation

Critics concerning the real impact of traditional microfinance as a tool for poverty alleviation are becoming frequent. In contrast, the financial crisis brought out interest for Islamic finance, whose models have been increasingly studied. Today, the real challenge lies in evaluating the impact of microfinance in a complex environment, where both Islamic and conventional microfinance institutions exist and address evolving clients in constant interaction. New methods and models are therefore needed in order to test the efficacy and assess the impact of introducing Islamic microfinance products, compared to the conventional system. In this context, this paper proposes an approach to build an Agent-Based Modeling (ABM) framework, which is aiming to test the effects of such products implementation using Islamic interest-free group loans. It also helps assess the impact of the behavioral biases as well as agents’ interactions within the repayment process.JEL Codes - C63; G2

Effectiveness of Nursing Guidelines on Nurses’ Performance Regarding High Alert Medications at Neonatal Intensive Care Units

Context: A high alert medication (HAM) is a medication that causes serious harm if it is used in error. Neonatal nurses are responsible for administering HAMs; incorrect administration can significantly affect clinical outcomes.Aim: The study aimed to evaluate the effectiveness of nursing guidelines on nurses' performance regarding HAMs at neonatal intensive care units (NICUs). Methods: A quasi-experimental design (pre/post-test) was utilized. The study was conducted at NICUs in Children's Hospital and Maternity and Gynecological Hospital affiliated to Ain Shams University. A convenience sample of 80 nurses caring for high-risk neonates was included in the current study from the previous setting for six months. Two tools were used to collect data. They are a structured interview questionnaire and nurses’ performance observational checklist. Results: The nurses' mean age was 27.79±6.83. 35% of them were worked part-time jobs. A highly statistically significant improvement was shown post-test compared to the pre-test regarding the nurses' knowledge and practices about HAMs at 0.001. Conclusion: The present study concludes that applying nursing guidelines interventions improved the neonatal nurses' knowledge and practice related to HAMs. The study recommended emphasizing the importance of using nursing guidelines for HAMs interventions for improving neonatal nurses' knowledge and practices at NICUs

L’énergie solaire : Un moteur du développement durable en Algérie

Depuis peu, l’énergie solaire s’avère être l’une des solutions alternatives face à notre dépendance aux énergies fossiles, cette énergie propre, inépuisable permet de fournir dix mille fois plus d’énergie que celle consommée par toute la population mondiale (Funk, 2010). De ce fait, développer cette filière demeure une priorité pour de nombreux pays et ce afin d’y parvenir à un développement durable sur ces trois dimensions : économique, sociale et environnementale. Ainsi, notre étude consiste à évaluer la contribution de l’énergie solaire au développement durable en Algérie. Pour ce faire, nous avons opté pour une méthodologie descriptive et analytique qui nous a conduits à conclure que les réalisations des projets d’énergie solaire en Algérie, dominées par la photovoltaïque, restent timides ne dépassant pas les 375 MW (Ministère de l’Énergie, 2018a), néanmoins cette capacité installée a réussi à résoudre une partie des problèmes environnementaux et socio-économiques qui entravent le pays, ce qui nécessite plus de volonté afin de corriger les mécanismes de son développement et aboutir aux résultats souhaités. Mots Clés: Energie Solaire; Photovoltaïque; Capacités Installées; Développement Durable ; Algérie

Terrorism:an analysis of the international legal framework, international and regional responses case study: Syria.

International law, as a discipline, is obsessed with crises, requiring reinterpretation of its basic principles to cope with them. Through this process of reinterpretation, it also creates new rules. Terrorism is one such ‘crisis’ which has impacted the international legal framework on the use of force, making it deviate from its basis established by the United Nations Charter. This thesis conducts a macro analysis of the changes in the legal framework for combating terrorism after 9/11 and the Arab Spring. It focuses on the Syrian conflict as a case study, analyzing the major actors and their different legal justifications. The Syrian conflict is a clear prototype of the changes that started to take place after 9/11. The development in the legal framework governing the use of force happened in three dimensions. The first is the broadening of existing rules (such as favoring a purpose-oriented interpretation of self-defense to include new forms such as anticipatory and pre-emptive self-defense). The second dimension is the creation of new rules through state practice that replaced existing codified ones, in an attempt to avoid the deadlock of the Security Council (SC) veto. For example, the “unwilling and unable†standard is used to justify unilateral interventions without the SC authorization to fight terrorists in other states. A third dimension is the gradual decline of the use of collective security under the UN system, giving way to unilateral action by States

UAV-CLOUD: A PLATFORM FOR UAV RESOURCES AND SERVICES ON THE CLOUD

UAVs - Unmanned Aerial Vehicles – have gained significant attention recently, due to the increasingly growing range of applications. However, developing collaborative UAV applications using traditional technologies in a tightly coupled design requires a great deal of development effort, time, and budget especially for heterogeneous UAVs. Moreover, monitoring and accessing UAV resources using traditional communication media suffer from several restrictions and limitations. This research aims to simplify the efforts, reduce the time, and lower the costs of developing collaborative applications for distributed heterogeneous UAVs. In addition, the research aims to provide ubiquitous UAV resources access. A platform is proposed for developing distributed UAVs. This platform provides services to simplify application development. In this approach, UAVs are integrated with the Cloud Computing paradigm to provide ubiquitous access to their resources and services. Due to the limited capabilities of UAVs, a lightweight architecture is adopted. UAV resources and services are modeled in a Resource Oriented Architecture which is a new flexible web service design pattern with loosely coupled interaction between services. Hence, they are accessed as Representational State Transfer RESTful services using HTTP. Moreover, the research proposes using a broker architecture to increase efficiency by separating responsibilities. Therefore, it separates the requester’s logic and functionalities from the provider’s. It also takes the responsibility for allocating the issued request to the available and suitable UAV(s). To test the proposed platform, I first developed the UAV resources as a payload subsystem then provided them with Internet connectivity. Then, resource identifiers and uniform interfaces were developed using the RESTful Application Programming Interfaces (APIs). I also developed the broker service along with a database containing the information of the registered UAVs and their resources. The platform system components were tested using a requester interface in a browser by issuing a request for a resource to the broker to find and request the service from a suitable UAV. The test was done for retrieving data from UAVs as well as requesting actions from them. The main contributions of this research are proposing the UAV-Cloud platform for simplifying the development of ubiquitous UAV applications and its vii perspectives, as well as a lightweight loosely coupled design for UAV resources. Another contribution is developing the broker architecture for separating responsibilities in this platform