Influence of accelerated curing on the compressive strength of polymer-modified concrete

In recent building practice, rapid construction is one of the principal requisites. Furthermore, in designing concrete structures, compressive strength is the most significant of all parameters. While 3-d and 7-d compressive strength reflects the strengths at early phases, the ultimate strength is paramount. An effort has been made in this study to develop mathematical models for predicting compressive strength of concrete incorporating ethylene vinyl acetate (EVA) at the later phases. Kolmogorov-Smirnov (KS) goodness-of-fit test was used to examine distribution of the data. The compressive strength of EVA-modified concrete was studied by incorporating various concentrations of EVA as an admixture and by testing at ages of 28, 56, 90, 120, 210, and 365 d. An accelerated compressive strength at 3.5 hours was considered as a reference strength on the basis of which all the specified strengths were predicted by means of linear regression fit. Based on the results of KS goodness-of-fit test, it was concluded that KS test statistics value (D) in each case was lower than the critical value 0.521 for a significance level of 0.05, which demonstrated that the data was normally distributed. Based on the results of compressive strength test, it was concluded that the strength of EVA-modified specimens increased at all ages and the optimum dosage of EVA was achieved at 16% concentration. Furthermore, it was concluded that predicted compressive strength values lies within a 6% difference from the actual strength values for all the mixes, which indicates the practicability of the regression equations. This research work may help in understanding the role of EVA as a viable material in polymer-based cement composites.     

Comparative Evaluation Of Surface Water Availability,Wastewater Reuse And Desalination In Saudi Arabia

ABSRTACT

There is a growing concern in the Kingdom of Saudi Arabia to exploit water resources of acceptable quality to meet demands in domestic, industrial, and agricultural sectors. The agricultural water need, which constitutes approximately 84% of the total demand, was estimated to be 7430 million cubic meters in 1985. The annual domestic and other demands amounted to 1400 million cubic meters for 1985. Various alternative supplies to meet these demands are surface water, renewable groundwater resources, reclaimed wastewater, desalinated water, and non-renewable groundwater. Due to excessive withdrawal of water from deep aquifers, considerable drawdown has recently been noticed.

This paper reviews the existing and future trends in developing surface water resources, reclamation of waste-water from various towns and cities and its use, and the role of desalination plants in the coastal regions of the Arabian Gulf and Red Sea. These alternatives are evaluated and compared in economic terms. Cost-capacity relationships are developed for various alternatives which will be used in developing long-term plans for optimum allocation of available resources in different parts of the Kingdom.     

Channel characterization of EM waves propagation at MHz frequency through seawater

Electromagnetic (EM) communication is considered as a suitable physical layer choice for SeaWater. SeaWater EM communication presents advantages over acoustic and optical in shallow water and deep oceans.Theoretical analysis of EM wave propagation in SeaWater helps us to estimate maximum distance covered in SeaWater at multiple depth points up to 5500 m. Mathematics of EM propagation in SeaWater (conducting medium) shows dependence on f (Hz), ? (F/m), and σ(S/m) of transmission medium. This paper presents channel characteristics of EM waves propagation at 1 to 20 MHz frequency through SeaWater based on real time data of SeaWater T (C°) and S(ppt) for averaged decades from 1955 to 2012 up to 5500 m.We estimated SeaWater σ (S/m), ?_r (F/m) (using Stogryns model), α (Np/m) (using Helmholtz model), Z(ohms), f_T(Hz), v_p(m/second), τ(second), and P_r(dBm) (using Maxwell equations and Friis law). Analysis of these parameters against multiple depths of SeaWater and frequencies shows that we can not assume constant σ (S/m) (4), ?_r (F/m) (81), f_T (Hz) (888 MHz),v_p(m/second) (3.33?10⁷), and τ (second) (8.2?10^?12) for SeaWater. Estimated P_r(dBm) helped us to analyze that for lower transmission frequencies (means higher ) and for lower σ(S/m), P_r(dBm) decays linearly. While for higher frequencies (means lower ) and for higher σ(S/m), P_r(dBm) faces sudden exponential decay. That negates sudden exponential delay (in general) of P_r(dBm) in SeaWater; it was only possible by assuming constant SeaWater ?_r (F/m) and σ(S/m). Our paper illustrates radio frequency communication for SeaWater in 1 to 20 MHz range and also provides comprehensive performance analysis using MATLAB simulation tool.     

Full‐complexity polytopic robust control invariant sets for uncertain linear discrete‐time systems

This paper presents an algorithm for the computation of full‐complexity polytopic robust control invariant (RCI) sets, and the corresponding linear state‐feedback control law. The proposed scheme can be applied for linear discrete‐time systems subject to additive disturbances and structured norm‐bounded or polytopic uncertainties. Output, initial condition, and performance constraints are considered. Arbitrary complexity of the invariant polytope is allowed to enable less conservative inner/outer approximations to the RCI sets whereas the RCI set is assumed to be symmetric around the origin. The nonlinearities associated with the computation of such an RCI set structure are overcome through the application of Farkas' theorem and a corollary of the elimination lemma to obtain an initial polytopic RCI set, which is guaranteed to exist under certain conditions. A Newton‐like update, which is recursively feasible, is then proposed to yield desirable large/small volume RCI sets.     

A compact uniplanar antenna for nine‐band LTE/WWAN operation in tablet computers

A compact uniplanar dual wideband antenna for tablet computers is presented. The proposed antenna provides full coverage of LTE700/2300/2500, GSM850/900/1800/1900, UMTS2100, Bluetooth, and 2.4‐GHz WLAN bands with a very small foot print 30 × 10 mm². The antenna has uniplanar structure and is easy to fabricate on single side of 0.8‐mm thick FR4 substrate. This is achieved through three optimized strips: a feeding strip, an inductively coupled inverted L‐shaped strip, and a shorted strip embedded with SMT components. The proposed design supports more than eight operating bands in 3:1 VSWR standard, exhibiting positive gains over all nine bands of operation and 80%–90% radiation efficiency in the higher LTE and WWAN bands. © 2016 Wiley Periodicals, Inc. Int J RF and Microwave CAE 26:496–502, 2016.     

RePizer: a framework for prioritization of software requirements

The standard software development life cycle heavily depends on requirements elicited from stakeholders. Based on those requirements, software development is planned and managed from its inception phase to closure. Due to time and resource constraints, it is imperative to identify the high-priority requirements that need to be considered first during the software development process. Moreover, existing prioritization frameworks lack a store of historical data useful for selecting the most suitable prioritization technique of any similar project domain. In this paper, we propose a framework for prioritization of software requirements, called RePizer, to be used in conjunction with a selected prioritization technique to rank software requirements based on defined criteria such as implementation cost. RePizer assists requirements engineers in a decision-making process by retrieving historical data from a requirements repository. RePizer also provides a panoramic view of the entire project to ensure the judicious use of software development resources. We compared the performance of RePizer in terms of expected accuracy and ease of use while separately adopting two different prioritization techniques, planning game (PG) and analytical hierarchy process (AHP). The results showed that RePizer performed better when used in conjunction with the PG technique.     

Anomaly Detection in ICS Datasets with Machine Learning Algorithms

An Intrusion Detection System (IDS) provides a front-line defense mechanism for the Industrial Control System (ICS) dedicated to keeping the process operations running continuously for 24 hours in a day and 7 days in a week. A well-known ICS is the Supervisory Control and Data Acquisition (SCADA) system. It supervises the physical process from sensor data and performs remote monitoring control and diagnostic functions in critical infrastructures. The ICS cyber threats are growing at an alarming rate on industrial automation applications. Detection techniques with machine learning algorithms on public datasets, suitable for intrusion detection of cyber-attacks in SCADA systems, as the first line of defense, have been detailed. The machine learning algorithms have been performed with labeled output for prediction classification. The activity traffic between ICS components is analyzed and packet inspection of the dataset is performed for the ICS network. The features of flow-based network traffic are extracted for behavior analysis with port-wise profiling based on the data baseline, and anomaly detection classification and prediction using machine learning algorithms are performed.     

Employing spatially constrained ICA and wavelet denoising, for automatic removal of artifacts from multichannel EEG data

Detecting artifacts produced in electroencephalographic (EEG) data by muscle activity, eye blinks and electrical noise, etc., is an important problem in EEG signal processing research. These artifacts must be corrected before further analysis because it renders subsequent analysis very error-prone. One solution is to reject the data segment if artifact is present during the observation interval, however, the rejected data segment could contain important information masked by the artifact. The independent component analysis (ICA) can be an effective and applicable method for EEG denoising. The goal of this paper is to propose a framework, based on ICA and wavelet denoising (WD), to improve the pre-processing of EEG signals. In particular we employ concept of the spatially constrained ICA (SCICA) to extract artifact-only independent components (ICs) from the given EEG data, use WD to remove any cerebral activity from the extracted-artifacts ICs, and finally project back the artifacts to be subtracted from EEG signals to get clean EEG data. The main advantage of the proposed approach is faster computation, as it is not necessary to identify all ICs. Computer experiments are carried out, which demonstrate effectiveness of the proposed approach in removing focal artifacts that can be well separated by SCICA.     

Biomass-derived nitrogen-rich porous carbon composite for supercapacitor application

In this study, egg proteins are used as a nitrogen source for the synthesis of nitrogen-rich carbonaceous material through hydrothermal carbonization (HTC) for the electrochemical energy storage application. The composite of activated carbon with egg-derived protein (AC/EDP) is prepared by mixing untreated egg proteins in the aqueous dispersion of activated carbon, followed by HTC at 220 °C for 12 h in a Teflon-lined autoclave. The resultant composite is then directed to chemical activation with KOH and thermal activation at a temperature ranging from 500 to 700 °C. The nitrogen-doped activated carbon exhibited a microporous and mesoporous structure with a high specific surface area of 1660 m² g^?1, confirmed through BET analysis. The composite morphology was analyzed through scanning and high-resolution transmission electron microscopy. X-ray photoelectron spectroscopy indicates the presence of a considerable amount of pyrrolic, pyridinic, and quaternary nitrogen in AC/EDP, which improved the electrochemical performance. The composite activated at 700 °C exhibited the highest capacitance of 263 F g^?1 at a current density of 0.2 A g^?1. The highest energy density and power density values are 32 Wh kg^?1 and 7920 W kg^?1, respectively. The AC/EDP exhibited high cyclic stability, and the capacitance retention observed after 10,000 cycles is 98%.