Reduced order modeling of fluid flows: Machine learning, Kolmogorov barrier, closure modeling, and partitioning

In this paper, we put forth a long short-term memory (LSTM) nudging framework for the enhancement of reduced order models (ROMs) of fluid flows utilizing noisy measurements. We build on the fact that in a realistic application, there are uncertainties in initial conditions, boundary conditions, model parameters, and/or field measurements. Moreover, conventional nonlinear ROMs based on Galerkin projection (GROMs) suffer from imperfection and solution instabilities due to the modal truncation, especially for advection-dominated flows with slow decay in the Kolmogorov width. In the presented LSTM-Nudge approach, we fuse forecasts from a combination of imperfect GROM and uncertain state estimates, with sparse Eulerian sensor measurements to provide more reliable predictions in a dynamical data assimilation framework. We illustrate the idea with the viscous Burgers problem, as a benchmark test bed with quadratic nonlinearity and Laplacian dissipation. We investigate the effects of measurements noise and state estimate uncertainty on the performance of the LSTM-Nudge behavior. We also demonstrate that it can sufficiently handle different levels of temporal and spatial measurement sparsity. This first step in our assessment of the proposed model shows that the LSTM nudging could represent a viable realtime predictive tool in emerging digital twin systems

Les déterminants de la distribution des cash flows dans les sociétés Marocaines cotées

The objective of this paper is to examine the determinants of the dividend distribution policy of companies listed on the Moroccan stock exchange, more precisely, this work seeks to highlight the effect of concentration, family shareholding, profitability and previous distribution on the dividend. In order to answer this problem, we adopted a panel made up of 37 listed companies, giving rise to 222 observations distributed between 2013 and 2018, tested by the GMM estimator in the "R" software. The results of this work, affirm in this context of emergence, a positive and significant effect, of the profitability and the previous distribution. As well as a negative effect of the concentration of capital and family shareholding on the distribution of dividends.L'objectif de ce papier est d’examiner les déterminants de la politique de distribution de dividendes, des sociétés cotées en bourse Marocaine, plus précisément, ce travail cherche à mettre en exergue, l’effet de la concentration, de l’actionnariat familial, de la rentabilité et de la distribution antérieure sur le dividende. Afin, de répondre à cette problématique, nous avons adopté un panel constitué de 37 sociétés cotées, donnant lieu à 222 observations réparties entre 2013 et 2018, testé par l’estimateur GMM dans le logiciel « R ». Les résultats de ce travail, affirment dans ce contexte d’émergence, un effet positif et significatif, de la rentabilité et de la distribution antérieure. Ainsi qu’un effet négatif de la concentration du capital et de l’actionnariat familial sur la distribution de dividende

Aluminum, Gallium, Indium And Iron Supported Onto Rice Husk Ash Silica As Catalysts For The Friedel-Crafts Alkylation Reactions Of Aromatic Compounds [QC173.4.P67 S165 2008 f rb].

Mangkin RHA-Al, RHA-Ga, RHA-In dan RHA-Fe telah disediakan dengan mengubahsuai permukaan silika abu sekam padi (RHA) dengan menggunakan ion Al3+, Ga3+, In3+ dan Fe3+. The heterogeneous catalysts derived from rice husk ash (RHA) silica were prepared by modifying the surface of silica extracted from RHA with Al3+, Ga3+, In3+ and Fe3+ ions

Traffic Solution and Improvement for the Area Surrounding Shubra Museum in Taif City, KSA

Planning and design of road infrastructure are based on determination of traffic flow parameters and their distribution in the observed area in terms of space and time. For the purpose of selecting the optimal solution of the planned period, it is necessary to conduct research of relevant traffic flow parameters in characteristic conditions of the observed road network. Taif city is located in the western zone of the Kingdom of Saudi Arabia where it is the eastern port of the Holly Capital, Makkah. In addition, it is a major touristic destination for citizens throughout the year. Despite this importance, Taif city needs to develop traffic flow, especially in downtown because of high traffic congestion, traffic accidents, location of city and the increasing population annually. This paper shows the solution of traffic systems and improving of the area surrounding of Shubra museum in Taif City. The engineering calculations such the peak hour factor, peak hour volume and engineering designs of the roads, pedestrians and design of the parking to achieve the KSA vision 2030 taking into consideration national and global codes within the realistic constrains and reduce the cost as much as possible. The alternatives proposed were studied within the current road networks surrounding the Shubra Museum in downtown Taif to obtain the optimized alternative, in order to find a sustainable future traffic flow. The proposed alternatives based upon international and national standards for highways design, AASHTO, Highway Capacity Manual (HCM), American Society for Testing and Materials (ASTM) and Specifications of Saudi Ministry of Transportation. Results revealed that the proposed alternatives achieved better performance in terms of traffic regulation in downtown Taif city. Also, the wide area obtained around the museum showed a better performance in terms of organizing the pedestrian movement and the comfort of the visitors as well as the museum achieving its goals very efficiently in the future. Moreover, construction of tunnel reduces the traffic congestions in the future and increases the area on the front of museum by 60 %. Although the high cost of constructing a concrete tunnel in the front area of the museum which needs extensive geotechnical and structural studies, the positive environmental impacts give this alternative more advantages as a viable and sustainable alternative. 

A New Heuristic for Scheduling Optimization of Non-Repetitive Construction Projects under Constrained Resources

In Sudan, the clients, contractors and consultants (stakeholders) suffer from the elongation of project completion time, especially in the case of limited resources. This problem results in the conflict among them, and hence leads to project delay that consequently influences the overall project cost. To solve this problem, data from ten construction projects executed in Khartoum state and other towns was collected, simulated and analyzed. Primavera software program was used as a simulator tool and sixteen selected heuristics were applied to the ten projects. Statistical and operational research tools combined with the existing heuristics, while considering best common practices in construction industry, were used. Lindo software, as a decision making tool, is then used to find the optimum solution, i.e., finding the minimum time to complete the project under limited resources. The results were then evaluated and, hence, concluded that the optimum solution of the extra needed time at its minimum possible rate (to complete the project under limited resources) was achieved as a result of implementing the heuristic of “minimum late start time”. This new “selected” heuristic optimizes the scheduling time of non-repetitive projects while considering the availability of limited resources

Effects of the Raising the Minimum Legal Purchasing Age for Tobacco on Cigarette, Cocaine and Inhalant Consumption

Over the past few years, several states have passed laws that increase the minimum legal purchasing age (MLPA) for tobacco from 18 to 21 years. This study examines the impact of statewide MLPA laws on youth tobacco consumption. Using data from the 2009-2019 Youth Risky Behavior Surveys (YRBS) and a difference-in-differences approach, I find that the enactment of MLPA laws is associated with a decrease in tobacco usage among adolescents. I also find that MLPA laws have important spillover effects to other youth risky behaviors. MLPA law adoption is associated with a reduction in cocaine use and inhalant abuse

Comparison between Giemsa and Van Geison stains in demonstration of collagen fibers (Kosti-2016)

Trichrome stain (such as Van Geison) is usually used in histopathology laboratory for demonstration of collagenic fibers. Lack of selectivity and tendency of stain to fade makes van Gieson not ideal for collagen demonstration. This study was aimed to compare between Giemsa's and van Gieson's stains in collagen fibers  demonstration. Twenty biopsies were obtained from rabbit’s skin after anesthesia by chloroform and immediately fixed by 10% neutral buffered formalin for 48 h. Then samples were processed using tissue processing machine and sectioned by rotary microtome. Two hundred (200) tissue sections of 5 micron thickness were prepared. A 100 tissue sections was stained by Van Geison and another 100 tissue sections stained by Giemsa. The stained section was compared with illustrated photomicrographs in order to assess staining quality. Best collagen staining quality was obtained by Van Geison's 60 (60%) and 40 (40%), mean 1.40, followed by Giemsa's stain excellent 55 (55%) and good 45 (45%), mean 1.45. Conclusively, Van Geison's is superior but Giemsa stain is rapid, sensitive without fading tendency, easy to perform and low cost and can be used as special stain under optimized conditions.Key words: Collagen, Giemsa, Van Geison

Sonographic evaluation of normal liver, spleen, and renal parameters in adult population: A multicenter study

Objective: To determine the normal liver, spleen, and renal parameters in adult patients with no comorbidities. Study Design: Cross-sectional study. Place and Duration of Study: Dow Institute of Radiology, Ojha Campus, LEJ Campus, and Al-Mustafa Hospital Karachi, from October 2016 to March 2017. Methodology: A total of 3,136 study participants with more than 16 years of age of either gender underwent ultrasound examination. All individuals with morbid conditions like hypertension (HTN), diabetes mellitus (DM), liver cirrhosis, hydronephrosis, renal cyst, and liver mass were excluded. Ultrasound scan was performed and longitudinal and transverse sections were obtained of both kidneys (in full inspiration), spleen and liver. Results: A significant positive correlation was observed between age and spleen size of the individuals (r=0.053, p=0.012). The correlation of BMI and liver size was also found significantly positive (r=0.237, p \u3c0.001). The correlation of age and kidney size was found significantly negative in between age and right kidney (r=-0.074, p \u3c0.001) and left kidney (r=-0.087, p \u3c0.001). Similarly, the correlation of BMI and renal size was found significantly weak positive between BMI and right kidney (r=0.206, p \u3c0.001) and BMI and left kidney (r=0.227, p \u3c0.001). Conclusion: BMI was found significantly positively correlated with liver size and both kidneys in study participants. Moreover, spleen was found directly and renal size inversely correlated with age of the individuals