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This paper presents the application of Compressive Sensing (CS) theory in radar signal processing. CS uses the sparsity property to reduce the number of measurements needed for digital acquisition, which causes reduction in the size, weight, power consumption, and the cost of the CS radar receiver. A well-known CAMP algorithm was used to reconstruct the compressed sparse LFMCW radar signal and improves its Signal-to-Noise Ratio. An Adaptive recovery CAMP algorithm, which had been proposed to deal with pulsed radar signal instead of the CAMP algorithm, in order to manage the problems of the limited number reconstructed targets, according to the incoherence property of the traditional CAMP algorithm, as well as reduce the complexity of the reconstruction algorithm. In present work, the Adaptive recovery CAMP algorithm will be applied to the LFMCW radar signal to enhance the detection performance and the number of detected targets in the LFMCW radar. Simulation results are done to evaluate the proposed algorithm compared with the traditional algorithm, for detection performance evaluation between the proposed algorithm and the traditional algorithm using the Receiver Characteristic Curve (ROC), the number of detected targets, the resolution performance, and the complexity evaluation.

Modern DVFS-enabled SoCs require nimble supply regulators that rapidly respond to abrupt load changes and offer fine resolution (e.g., 12.5mV in [1], 10mV in [2]) over large voltage and current dynamic ranges. Switch-array digital LDOs (SA-DLDOs) are a potentially attractive regulation option due to their ability to operate with low input voltages and in part to their modular digital nature and scalability. SA-DLDOs employ 2” unary-[3] or binary-weighted [4] PMOS arrays that are modulated through a 1b or multi-bit ADCs to maintain the output voltage (V out ) at the desired level (V ref ), as shown in Fig. 18.7.1 (top left). Unfortunately, while array conductance in SA-DLDOs linearly increases with equal step size ( g LSB) as the code is increased, the output voltage step, v LSB, does not; in fact, v LsB is nonlinear: ∼G L V out × G LSB. Thus, SA-DLDOs achieve a nonlinear steady-state error, e ss = V eef − V out ≈ ± g LSB/G l χ V u!op , as shown in Fig. 18.7.1 (bottom left), that deteriorates at large dropout voltages, V drop = V in − V oitt , and at small loads, G l . As a result, the required supply step of 10mV (with ±15% typical accuracy) to perform per-core DVFS over a typical 100χ I L dynamic range requires an impractical 16b PMOS array resolution. Even with limit-cycle oscillations, the load range that can achieve ±1.5mV accuracy is provably limited to 2N-6, 7 at V eef =VJ2 (Fig. 18.7.2, top left), which would still require a 14b array resolution that, even if it were feasible to build, would come with linearly (for binary search) or exponentially (for linear search) increased response time (T R ), quiescent power (IQ), and area.

Recent advancements in integrated radio design have enabled many new applications ranging from wearable health-care or fitness monitors to Internet of Things devices, structural integrity monitors, and beyond. In many of these applications, device size and battery life are of critical importance. Since radios often consume a significant portion of the power budget in small sensing nodes [1], reducing radio power consumption is an effective way to decrease battery size or increase battery life. Reducing radio power consumption can be challenging as there are important tradeoffs between power consumption and performance metrics such as radiated output power, linearity, sensitivity, channelization capabilities, and interference sensitivity. Low-power radio designs often sacrifice one or more of these metrics in the pursuit of low overall power consumption.

Postoperative nausea and vomiting (PONV) is a common and distressing clinical problem following surgery and affects 1 in 4 patients. If not treated appropriately PONV can potentially increase mortality (e.g. through aspiration and dehydration) and morbidity, either as a result of vomiting or from the effects of vomiting. This article is educational and informative and aims to give the practitioner a concise outlook when considering the management of PONV. With regards to recent advances, ‘The Consensus Guidelines for the Management of Postoperative Nausea and Vomiting’ ( Gan et al, 2014 ) are the most relevant and up-to-date guidelines. These guidelines help to identify patients who are more at risk of PONV and recommend different approaches in reducing that risk. These recommended approaches include the identification of the most effective anti-emetics, either single or combined therapies (pharmacological and non-pharmacological) for prophylaxis and prevention, and strategies for treatment of PONV when it actually occurs.

In this study AlSi10 Mg/Al2O3 composite was processed via selective laser melting. The influence of different process parameters namely, laser power, scan speed and hatch spacing was investigated to determine their effect on the physical and mechanical properties of the consolidated powders. Input energy and balling effect, had a major influence on the developed pore morphology. Poor consolidation associated with poor heat diffusion and insufficient melting occurred at the low input energy. Intermediate input energy resulted in the formation of continuous porosity along the building direction separated by consolidated zones of equal width and associated with uniform balling effect. High input energy developed distorted porosity with non-uniform distribution associated with irregular course balling. The formed continuous porosity is attributed to the segregation and migration of alumina particles to the spacing between the deposited successive powder layers followed by their selective melting forming oxide films that acts as a barrier to the complete solidification.

Sediment samples have been collected from Lake Nasser during drought and flooding periods to study the effect of flood season on bottom sediment distribution and mode of transportation. Ten sectors with three sites in each sector were chosen from upstream of Aswan High Dam to Adindan. The study showed that Lake Nasser sediments are heterogeneous and are mainly silty clay and clayey silt. Eastern and western sides of the lake include more sand. Depth controlled distribution of grain size (deeper is finer). Sands increase with the starting of the flood season. During drought periods suspension was the most predominant mode of transportation; i.e. sediments transported by a medium of considerable density. During flooding period siltation and suspension were most predominant modes of transportation; i.e. environment with a high energy, various overlapping processes, and variety of depositional environments. C–M diagram indicates that sediments during drought periods behaved as pelagic suspension in which sediments settled from a suspension in stagnant water, rolling; overbank facies suspension and uniform suspension were of less importance. During the flooding period there was no clear trend for studied sediments of pelagic suspension; rolling, graded suspension, overbank facies suspension, suspension, and uniform suspension were widely distributed.

This paper combines application of Compressive Sensing theory in radar signal, and the approach of the Xampling. Based on the characteristic of sparse radar signal, it can be sampled at Finite Rate of Innovation (FRI) [1], Xampling converts high dimensional signal to a lower dimensional signal using Fourier coefficients directly from analog signal [2]. A well-known CAMP algorithm was used to reconstruct the under sampled sparse radar signal and improves its Signal-to-Noise Ratio in case of received radar signal has a high SNR [3]. In present work, a proposed algorithm called Adaptive CAMP algorithm is applied to the radar signal in order to deal with the problem of the false alarms that appear in reconstructed radar signal from the CAMP algorithm in case of received low SNR. The performance of the Adaptive CAMP algorithm as well as the CAMP algorithm is evaluated using the Receiver Characteristic Curve (ROC) to compare the proposed design with the CAMP algorithm in case of low SNR.

This paper describes the evolution of the design leading to the selection, development and delivery of Stones disconnectable Buoyant Turret Mooring (BTM) buoy. The optimization process leading to the selection and configuration of the BTM buoy is discussed, with particular focus given to the mooring- riser system payloads supported by the BTM when in the disconnected state. A hybrid design, featuring syntactic foam buoyancy modules integrated into a steel structural skeleton, and incorporating a minimal number of steel ballast tanks, was selected over a conventional all steel buoyant hull structure. The selected design provides for a protective steel cage for the buoyancy modules, and a structural path for mooring-riser system loads into the Floating Production, Storage and Offloading (FPSO), while a large number of syntactic foam blocks are secured within the steel frame to provide adequate buoyancy to meet the in-service performance requirements. A qualitative discussion about the advantages of the selected geometry and hybrid steel-foam design is presented, including the performance characteristics of disconnection, submergence equilibrium and ballasting. Beyond the design evolution considerations including concept selection and optimization, attention is given to manufacturing, constructability, offshore installation and operability under the latest US Gulf of Mexico (GOM) regulatory regime. The buoy's transit voyage from Singapore to the GOM for the initial offshore integration with the FPSO necessitated Transport and Installation (T&I) requirements which were embedded into the design and integration of all BTM buoy components. Buoy ballasting and de-ballasting strategy after mooring hookup and riser connection played a pivotal role in sizing critical components and equipment. In this context, the paper will explore the interrelations between design and operations in order to optimize the loading requirements. The design decisions leading to the selection of geometries, materials and configurations of the largest and deepest offshore mooring installation are discussed. A novel solution is developed to accommodate a complex deepwater installation with a large payload mooring-riser system. Feedback on onshore fabrication and offshore integration and operations are presented.

Cognitive Radio (CR) can solve the spectrum scarcity problem; also Compressive Sensing (CS) minimizes the required sampling rate lower than the ordinary Nyquist rate. In this work, a combined technique for detection and frequency estimation for Slow Frequency Hopping Spread Spectrum (SFHSS) based on CS and FFT Averaging Ratio (FAR) spectrum sensing algorithm is introduced. The proposed algorithm is merging FAR algorithm and Orthogonal Matching Pursuit (OMP) algorithm in order to enhance the signal detection capability. Using OMP is preferred in the proposed algorithm because it has the minimum complexity and sufficient performance among the most of CS reconstruction algorithms. Since it is composed of OMP and FAR, the proposed algorithm is called Enhanced Orthogonal Matching Pursuit (EOMP). EOMP operation is compared with both Incoherent Detection and Estimation Algorithm (IDEA) and Cosine Similarity (COSSIM) techniques for detection and frequency estimation for single primary user. EOMP has a good signal detection and frequency estimation performance compared with IDEA and COSSIM techniques but with increasing in sensing time, which can be compensated using parallel processing.

Modern subthreshold SoC designs feature multiple power domains to dynamically track the maximum energy-efficiency point (0.32–0.45V [1]) in response to application demands. While analog low-drop-out (LDO) regulators have shown rapid response times (e.g. T R = 0.65ns [2]) and excellent steady-state performance, they fail to operate at the low input voltages, V IN , typically supplied to such SoCs via either a high-efficiency switching DC-DC converter or an external harvesting source (e.g., V IN = 0.5V). On the other hand, digital LDOs (DLDOs) are becoming popular in low-voltage SoC designs where they can operate reliably from supplies down to 0.5V. However, conventional DLDOs respond slowly to large current steps, especially at low voltages (e.g., T R = ∼44ns, 57.1ns, and 4µs at V IN =1V [3–5], and 20µs at V IN =0.5V [1]). Furthermore, they suffer from limited dynamic range over which the load is regulated and stable (e.g. s , this comes at increased power consumption and, importantly, reduced loop stability. To address these issues, this paper presents a 0.5V 0.0023mm2 recursive all-digital LDO (RLDO) in 65nm with hybrid PD-SAR and PWM duty control that achieves 15.1ns and 100ns response and settling times, respectively, while maintaining 5.6mV/mA load regulation and loop stability across a 20,000× dynamic load range, eclipsing state-of-the-art active area, response time, settling time, and dynamic range metrics across prior-art digital LDOs by over an order of magnitude.

Clock distribution in modern SoCs consumes a significant fraction of total chip power. To reduce clock distribution power, resonant clocking schemes, where an inductive reactance is used to cancel the capacitive reactance of global clock networks at a given resonance frequency, f o , have been proposed. Conventionally, such schemes are only suitable at high multi-GHz frequencies in order to be able to place the employed inductors on chip [1, 2]. Since many modern energy-efficient SoC designs optimize for clock frequencies DD to the MHz and near-threshold regimes, respectively, there is a need to develop low-power clock distribution schemes that can work across increasingly wider operating ranges. Recent work in quasi-continuous resonant clocking has proposed intermittent cancelation of global clock-tree capacitance during edge transitions, however, such techniques require large off-chip inductors and are limited to 0.98MHz [3] and 150MHz [4], respectively, owing to the need to operate well below resonance (i.e., o /10). Thus, while prior-art has shown power reduction for targeted applications, they all require large on- or off-chip magnetics, and do not meet the MHz-to-GHz frequency-range needs of modern DVFS-enabled SoCs. To address these problems, this paper introduces a fully integrated adiabatic clocking scheme that efficiently synthesizes n-step clock waveforms from 1MHz to 2GHz via a switched-capacitor DC-AC multi-level inverter topology, theoretically reducing power by 1/n without using any magnetic component.

Introduction The concern on the effect of pupillary dilatation on visual field parameters in patients with glaucoma comes from the fact that patients usually seek field examination after their pupils have been dilated for fundus examination. Aim To investigate the influence of pupillary dilatation on visual field testing in patients with glaucoma, by using automated static perimetry. Patients and methods A prospective comparative noninterventional clinical study was conducted on 20 eyes (11 patients) with open-angle glaucoma. Two consecutive visual field examinations were performed on each eye of all participants. The first was done on the undilated normal pupil size, whereas the second was done after dilating the pupil to 6–8 mm. Results After pupillary dilatation, fixation losses were significantly higher. There was no significant difference in false-negative or false-positive results. There was improvement in the mean deviation with no statistical significance. Pattern standard deviation showed also improvement, which was statistically significant. Discussion and conclusion It was found that pupillary dilatation caused variability and difference in the visual field parameters, which emphasizes the importance of consistent pupillary size in performing the serial automated visual field tests, especially in patients with glaucoma to allow standardized judgment on the patient’s progression.

In Senegal, the evolution of disease as recorded by the public health care system confirms the preponderance of seeking care for infectious diseases (malaria, respiratory and diarrheal diseases) and reveals the emergence of chronic diseases. However, while the incidence of hypertension diagnosed by the public system increased from 14 to 81 per thousand inhabitants aged over 40, between 1995 and 2009, the diabetes appears only at 0.4‰, thus in contradiction with hospital data and general population surveys. For instance, diabetes prevalence was estimated at 10.4% in Saint-Louis in 2010 (8). This difference recalls the limitations of this data source as regards epidemiological information, but sheds light on the challenges facing the health care system, both in terms of detection, medical care, access to health care and treatment as well as cost recovery.

A Recursive Switched-Capacitor (RSC) topology is introduced that enables reconfiguration among 2 N -1 conversion ratios while achieving minimal capacitive charge-sharing loss for a given silicon area. All 2 N -1 ratios are realized by strategically interconnecting N 2:1 SC cells either in series, in parallel, or in a stacked configuration such that the number of input and ground connections are maximized in order to minimize cascaded losses. Importantly, all ratios are dynamically reconfigurable without disconnecting a single capacitor, all while ensuring optimal capacitance/conductance relative-sizing. The RSC topology is inherently regular, enabling recursive inter-cell connection and recursive binary-slicing that implement ratio-reconfiguration with minimum complexity and losses. A scalable all-digital binary search controller is employed to perform ratio-reconfiguration among the available 2 N -1 ratios without using any ratio-threshold generation circuitry. To validate the topology, a 4 bit RSC is fully integrated in 0.25 μm bulk CMOS using MIM capacitors, achieving greater than 70% efficiency over a 0.8-2.2 V output voltage range with 85.8% peak-efficiency from a 2.5V input supply. Compared to a co-fabricated three-ratio (1/3, 1/2, 2/3) Series-Parallel SC converter, the RSC achieves a 40.4% larger output operating range (from 0.04 to 2.2 V), and fills the efficiency-drops in-between the three-ratios by 8% with a 940 Ω load.

A first investigation into the production of amorphous and nanostructured Ti-based alloys with nominal compositions Ti 41.5 Zr 41.5 Ni 17 , Ti 61 Zr 22 Ni 17 , Ti 41.5 V 41.5 Ni 17 and Ti 61 V 22 Ni 17 by mechanical alloying (MA) technique is presented. This technique was adopted to produce alloys' powders with high fresh surface area that were active for hydrogen storage. Hydrogen absorption characteristics and structure changes in the alloys after hydrogenation were investigated. Gas phase hydrogenation of the Ti–Zr–Ni alloys, at 573 K and an initial hydrogen pressure of 2 MPa, exhibited good hydriding properties and started at a maximal rate without induction period with a hydrogenation capacity up to 1.2 wt%. However, hydriding of Ti–V–Ni alloys at the same conditions exhibited slower rates. The Ti 61 V 22 Ni 17 composition showed high hydrogen absorption capacity of 1.8 wt% and exceeded 4 wt% at 345 K. In addition, the Ti–V–Ni alloys showed structure stability after hydrogenation and retained the amorphous structure.

Fabrication and processing of 99.7% purity aluminum powder reinforced with 0, 5, 10% volume fractions NiAl intermetallic metal matrix composites were conducted. The mechanically alloyed nanostructured NiAl was mixed by both regular and high energy ball milling techniques. Powders of NiAl employed for reinforcement were milled for 18 and 31 h, and therefore denoted as NiAl18 and NiAl31, respectively. The mixed powders were consolidated via a combination of cold pressing followed by hot extrusion at 480 °C for 1 h at a reduction ratio 4:1. Hardness, tensile properties, and fracture behavior of the extruded composite powders were evaluated. Structural evolution of the milled composite powders was investigated before and after extrusion using optical microscopy, field emission scanning, and transmission electron microscopy. In addition, particle type identification was carried out via energy dispersive x-ray analysis. Introducing NiAl31 (0.8 µm) enhanced the mechanical properties of the composites compared to NiAl18 (1.0 µm). Moreover, powders milling enhanced the tensile properties post hot extrusion compared to the mixed conditions due to the enhanced reinforcement distribution and bonding with the Al matrices. Hot extruded milled composite powders of Al reinforced with 10% NiAl31 produced nanostructured high-angle grain boundary structure

Discs of monolithic AA6061 and AA6061 reinforced with SiCp were processed via combination of hot compaction of the mixed powders followed by high pressure torsion (HPT). HPT processing was investigated using incremental revolutions up to four, under pressures of 1 and 3 GPa. Structural evolution of the powders before and after HPT processing was investigated using scanning electron microscope (SEM). HPT processing of AA6061 discs produced a trimodel structure with micron-scale grains, subgrains and nanoscale substructure of 29, 1.9 μm, and 250 nm, respectively. Reinforcement with SiCp resulted in a refined structure with micron-scale grains, subgrains and nanoscale substructure of 25, 1.9 μm, and 184 nm respectively. The presence of SiCp at the triple junctions and along the grain boundaries enhanced the rate of strain hardening of the Al-matrices and significantly refined the grain size. More pronounced refinements of the grains, subgrains, and substructures were observed with increasing the HPT pressure up to 3 GPa.

Background Rice (Oryza sativa L.) is one of the leading food crops of the world, the staple food of over half the world's population. The bran, which is an important byproduct obtained during rice milling, constitutes about 1/10 of the weight of the rice grain. Rice bran is the outer brown layer including the rice germ that is removed during the milling process of brown grain. This milling byproduct is reported to be high in natural vitamins and minerals, particularly vitamin E. Objectives The present study was conducted to determine the chemical composition of bran and bran oil of 13 different rice varieties commonly produced in Egypt, to study the utilization of rice bran in bread production, and to assess the quality and acceptance of the rice bran edible oil produced. Methods Rice bran was produced from 13 Egyptian varieties of recently harvested rice as well as from paddy rice stored for 1 year. The extracted bran was immediately stabilized then subjected to chemical analysis (such as moisture content, protein, fat, carbohydrates, fiber, and ash) as well as trace and heavy metals determination (P, K, Na, Ca, Fe, Zn, Cu, and Mg). Bread was produced by adding Giza172 rice bran at three different concentrations to wheat flour then subjected to chemical analysis, caloric content, and organoleptic examination. Bran oil was extracted from the different varieties of rice bran (recently harvested and stored) then subjected to chemical and organoleptic examinations as well as vitamin E and oryzanol determination. Results The percentage of rice bran of newly harvested Egyptian rice was 11.68% and was 10.97% in stored rice. The analysis showed mean values of 5.91 and 5.53% for moisture, 14.60 and 14.40% for crude protein, 14.83 and 15.20% for fat, 44.77 and 45.40% for carbohydrates, 6.55 and 7.06% for crude fiber, and 8.87 and 8.50% for ash for newly harvested and stored rice bran, respectively. Bread containing 15% rice bran showed the highest score percentages for organoleptic quality compared with the control (100% wheat flour). Rice bran oil showed higher scores of taste, smell, appearance, and texture than corn oil and sunflower oil. Conclusion Rice bran contains high nutritional components as well as phytochemicals such as vitamin E (i.e. tocopherols and tocotrienols) and the γ-oryzanol fraction that have positive effects on human health. Storage of paddy rice before milling resulted in significant effect on all studied rice bran characters and rice bran oil characters under the present investigation except crude protein and carbohydrates characters. Recommendations Substitution of wheat flour with rice bran by 15% in bread production to fortify the bread with vitamin E and to reduce the amount of imported flour is recommended.

Deriving bulk materials with ultra-high mechanical strength from nanometer-sized single metalic crystals depends on the consolidation procedure. We present an accurate molecular dynamics study to quantify microstructure responses to consolidation. Aluminum single crystals with an average size up to 10.7 nm were hydrostatically compressed at temperatures up to 900 K and pressures up to 5 GPa. The consolidated material developed an average grain size that grew exponentially with the consolidation temperature, with a growth rate dependent on the starting average grain size and the consolidation pressure. The evolution of the microstructure was accompanied by a significant reduction in the concentration of defects. The ratio of vacancies to dislocation cores decreased with the average grain size and then increased after reaching a critical average grain size. The deformation mechanisms of poly-crystalline metals can be better understood in the light of the current findings.

One of the most important casting defects in Al alloys is thought to be the double-oxide film defect (bifilm) which has been reported to have a deleterious effect on the reproducibility of the mechanical properties of Al castings. Previous research has suggested that the atmosphere inside such bifilms could be consumed by reaction with the surrounding melt, which might decrease the size of the defects and reduce their harmful effect on mechanical properties. In order to follow the change in the composition of the interior atmosphere of a bifilm, analog air bubbles were held inside Al alloy melts, for varying lengths of time, and subjected to stirring, followed by solidification. The bubble contents were then analyzed using a mass spectrometer to determine the changes in their compositions with time. The results suggested that initially oxygen and then nitrogen inside the bubble were consumed, and hydrogen dissolved in the melt diffused into the bubble. The consumption rates of O and N as well as the rate of H diffusion were dependent upon the type of oxide, which was dependent on the alloy composition. The reaction rates were the fastest with MgO (in an Al-5Mg alloy), slower with alumina (in commercial-purity Al alloy), and the slowest with MgAl2O4 spinel (in an Al-7Si-0.3Mg alloy). It was estimated that the times required for typical bifilm defects in the different alloys to lose their entire oxygen and nitrogen contents were about 345 seconds (~6 minutes), in the case of Al-5Mg; 538 seconds (~9 minutes), in the case of a commercial purity alloy; and 1509 seconds (~25 minutes), in the case of the Al-7Si-0.3Mg alloy (2L99) due to the different oxides that the different alloys would be expected to form.

Many Nanoparticles (NPs) were reported to significantly enhance the production of biogas from the anaerobic digestion of organic wastes. Herein, two types of NPs (Ni-Ferrite and Ni-Co-Ferrite) were synthesized using the co-precipitation method and characterized using X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray spectroscopy (EDS) techniques. Three different concentrations (20, 70 and 130 mg/l) of each type were added to separate biogas reactors to study their effect on the biogas production compared to blank reactor. A pressure-based biogas reactor was designed and manufactured specifically to test the effect of the NPs on the anaerobic digestion process. The pressure of the daily produced biogas was monitored using a pressure transducer and the volume of the biogas was calculated at standard conditions of pressure (1.013 bar) and temperature (15 °C). The results showed an increase in the biogas production of 6.6%, 5.9% and 32.9% upon the use of Ni-Co-Ferrite NPS at concentrations of 20, 70, and 130 mg/l compared to blank reactor, respectively. In addition, the Ni-Ferrite NPs achieved biogas enhancements of 30.8%, 28.5%, and 17.9% at concentrations of 20, 70 and 130 mg/l, respectively.

In the current study, a comprehensive evaluation of AA5083 processed via the novel Multi-Channel Spiral Twist Extrusion (MCSTE) method was conducted. The induced stress-strain state and the deformation mechanism of multiple pass deformation via MCSTE dies with twist angle β (30°) and (40°) were analyzed using finite element analysis. Nanohardness measurements were carried out along the billet surfaces to validate the numerical model output. The micro-hardness, tensile-up-to-fracture, fracture behavior and microstructural properties were investigated. The numerical model and the empirical findings reveal that the increase in the mechanical properties of the billets processed via MCSTE die with a twist angle β (40°) was associated with a plastic strain of 0.9 (mm/mm) compared to 1.2 (mm/mm) for conventional twist extrusion dies of β (60°). For the MCSTE die with angle β (30°), the hardness and tensile properties increased as a function of increasing the number of passes, with an insignificant reduction in ductility. Processing via a die angle β (40°) was limited to one pass due to excessive strain hardening, which resulted in shear localization during the second pass. The detailed analysis presented herein validates the effectiveness of MCSTE processing as a severe plastic deformation tool with a favorable potential for industrial applications.

Clear understanding of the superior mechanical strength of nanometer-sized metal single crystals is required to derive advanced mechanical components retaining such superiority. Although high quality studies have been reported on nano-crystalline metals, the superiority of small single crystals has neither been fundamentally explained nor quantified to this date. Here we present a molecular dynamics study of aluminum single crystals in the size range from 4.1 nm to 40.5 nm. We show that the ultimate mechanical strength deteriorates exponentially as the single crystal size increases. The small crystals superiority is explained by their ability to continuously form vacancies and to recover them.

Amorphous nanostructure silicon carbide (a-SiC) recently received great attention for its use as protective coating for metallic substrates due to its good mechanical properties and corrosion resistance. In this article, a-SiC thin films were deposited on AISI 304 stainless steel substrates at room temperature for deposition times of 4 and 6 h using pulsed laser deposition technique. The deposition process was stopped every 2 h then resumed for an hour. The effect of interval time during deposition process and substrate type on the properties of the produced films was extensively investigated. The morphological features of the deposited SiC films were investigated using field-emission scanning electron microscope and atomic force microscope. The film structures were determined by transmission electron microscopy, X-ray photoelectron spectroscopy and energy-dispersive X-ray. The mechanical and tribological properties, such as Young’s modulus, hardness and scratch resistance, were determined using nanoindenter. The results showed the formation of uniform monocrystalline nanostructured Si interface between two a-SiC layers after the 2 h of no-deposition time intervals. The formation of crystalline Si interface attributed to the effect of high kinetic energy of the incoming ablated particles deposited on the grown a-SiC layers. The a-SiC films were amorphous having nanostructure grains with dimensions ≤ 100 nm. All films showed smooth surfaces with fine cracks due to the presence of intrinsic stresses. The deposited films showed low mechanical properties due to their amorphous structures.

One-dimensional core–shell nanostructured electrodes made of aligned TiO2 nanotubes (NTs)/ZnO were fabricated via the thermal sputtering of ZnO layers on anodically fabricated titania NTs. Increasing the ZnO sputtering time resulted in the increase in the shell thickness, which in turn showed different morphological, structural, and optical characteristics. The crystallinity of the core nanotubes was found to be a determinant factor in the formation of the NTs/ZnO heterojunctions as revealed by field emission scanning electron microscopy, glancing angle X-ray diffraction, X-ray photoelectron spectroscopy, and Raman analyses. Used as a photoanode to photoelectrochemically split water, the TiO2/ZnO heterojunction sputtered for 53 min showed an almost 80% increase in the photoconversion efficiency (7.3%) compared to that of pure TiO2 NTs (4.1%) under light illumination (320–400 nm, 100 mW/cm2, 0.5 M Na2SO4). This was confirmed via the incident photon conversion efficiency (IPCE) measurements, which showed an...

The mechanical properties of Al castings are reduced by inclusions, particularly double oxide films, or bifilms, which are formed due to surface turbulence of the liquid metal during handling and/or pouring. These defects have been reported not only to decrease the tensile and fatigue properties of Al alloy castings, but also to increase their scatter. Recent research has suggested that the nature of oxide film defects may change with time, as the air inside the bifilm would react with the surrounding melt leading to its consumption, which may enhance the mechanical properties of Al alloy castings. In order to follow changes in the composition of the internal atmosphere of a double oxide film defect within an Al melt, a series of analogue experiments were carried out to determine the changes in gas composition of an air bubble trapped in a melt of commercial purity Al, subjected to stirring. The bubble contents were analysed using a mass spectrometer to determine their change in composition with time. Also, the solid species inside the bubbles solidified in the melt were analysed. The results suggested that first oxygen and then nitrogen inside the bubble were consumed, with consumption rates of 2.5x10-6 and 1.3x10-6 mol m-2s-1, respectively. Also, hydrogen diffused into the bubble from the melt at an average rate of 3.4x10-7 mol m-2s-1, although the rate of H diffusion increased significantly after the consumption of most of the oxygen inside the bubble. Based upon these reaction rates the time required for a typical alumina bifilm to lose all its oxygen and nitrogen was determined to be just under 10 minutes.

Compressive Sensing (CS) theory is a newly developed theory which combines the signal sampling and compression based on the sparsity characteristics of the signal. Applying CS theory in radar signal processing may lead to a reduction in sampling rate, complexity, power consumption, and cost. On the other hand, performance is a critical point to be considered. In the present paper, an important question of the worthy of applying CS in the signal processing of Linear Frequency Modulated Continuous Wave (LFMCW) radar is considered. Two approaches of CS are considered; Nyquist rate based approach, and pseudo random based approach. The detection performance of LFMCW radar signal processor using CS based approaches is compared to the traditional one which is based on Fast Fourier Transform (FFT) through Receiver Operating Characteristics (ROC) curves. Comparative analysis between CS approaches and the traditional one regarding the performance and complexity is presented.

In the current work, Aluminum Alloy 2124-SiC/Graphene nanocomposite is fabricated via high energy milling followed by uniaxial cold compaction at 525 MPa, sintered at 450 °C, and followed by hot extrusion at 4:1 extrusion ratio. SiC nanoparticles (SiCNP) powders the G-micron-clusters forming G-coated-SiCNP (GCSiCNP) reinforcement filler, used for the reinforcement of AA2124 matrices via milling. The processed nanocomposite combines the properties suitable for dry wear resistant and self-lubricating solids. It is anticipated that the formation of GCSiCNP decreases the agglomeration of SiCNP producing uniform dispersion of the GCSiCNP reinforcement within the Aluminum matrices. Mechanical and wear resistance of the processed GCSiCNP nanocomposites were characterized compared to the milled AA2124 and AA2124-SiCNP nanocomposites processed under similar milling conditions. FESEM and XRD are used for the investigation of the milled powders crystallite size, lattice strain, and phases as well as powder morphology.

Mechanical alloying (MA) is one of the most commonly used methods in preparing metallic materials. We are especially interested in its ability to produce nanostructured materials. MA has rarely been used in producing nanostructured magnesium base alloys due to the process complexity and flammable nature of the alloy. In this work, high energy ball milling of elemental powders, Mg, Zn and Zr, was investigated for the MA of ZK50 alloy. Crystallite size, lattice strain, as a function of total milling energy (required for complete alloying) were characterized using X-ray diffraction. Scanning electron microscopy was employed to determine the influence of milling time on powder morphology. Consolidation of the milled powders into thin sheets was conducted via hot pipe rolling at 0.4 Tm. Results showed that complete alloying was achieved at 45 milling hours which was associated with particle size reduction to 600 nm and crystallite size of 8.8 nm.

The effect of excimer laser annealing on the structure and morphology of ceramic coatings were investigated. Alumina-40% zirconia (AZ-40) coatings were sprayed with a water-stabilized plasma spray gun. The coated surface was treated by excimer laser having a wavelength of 248 nm and pulse duration of 24 ns. The surface structure of the treated coating was examined by field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD). A detailed parametric study was performed to investigate the effects of different parameters such as laser energy density (fluence), pulse repetition rate (PRR), and the number of shots on the mechanical properties, surface morphology, and microstructure of the coatings. The results of this study indicated that laser energy and pulse repetition rate have significant effects on surface morphology, porosity, and microstructure of the coating.

This paper presents a DC-RF power inverter that efficiently synthesizes high-voltage RF waveforms directly from a battery voltage using thin-oxide CMOS switches. Instead of stacking transistors or employing large inductive transformation ratios, high output power is generated by switching individual class-D power amplifier (PA) cells in a 2-phase house-of-cards (HoC) topology to provide voltage addition of the cells outputs without exceeding device voltage ratings, effectively resulting in a solid-state RF impedance transformer. High-efficiency at backoff is then achieved by capacitively combining the output of two HoC networks nominally set to generate different amplitudes, enabling voltage-mode Doherty-like backoff without a bulky transmission line. The PA is implemented in 65nm bulk LP CMOS, operates from 4.8V, and provides a battery-to-RF efficiency above 40% at both 23dBm and 6dB backoff at 720MHz.

Application of Compressive Sensing (CS) in Linear Frequency Modulation Continuous Wave (LFMCW) radar had been investigated and proved by the authors in [8]. An approach, namely architecture 1, had been evaluated by the authors in [11] which dependent mainly on applying CS in range direction. But there is a limitation on the number of the detected targets in range. So, in the present paper, a new approach for applying CS in LFMCW radar signal processing, namely architecture 2, is introduced depends on apply CS in azimuth direction (range sweeps). The reduction in range sweeps is performed using a Pseudo Random (PN) sequence in Azimuth according to the required reduction ratio in range sweeps. The information of the received radar signal (target range and speed) are reconstructed by the use of Complex Approximate Message Passing (CAMP) reconstruction algorithm. Performance of the proposed LFMCW radar signal processors based on CS (architecture2) is evaluated and compared to that of both the traditional one based on Fast Fourier Transform (FFT)) and architecture 1 from points of view of detection performance through Receiver Operating Characteristics (ROC) curves, resolution performance and hardware complexity. The proposed approach (architecture 2) is designed and implemented using Field Programmable Gate Array (FPGA).

In the current research, mechanical alloying (MA) was employed to synthesize nanostructured Al-5.7wt.%Ni eutectic alloy through the variation of the milling parameters. Three-dimensional parametric phase diagrams were constructed for the alloy start and complete formation times over a range of ball-to-powder ratio (BPR), rotational speeds (RPM) and milling time (MT). Total energies of 224 kJkg− 1 and 1068 kJkg− 1 were necessary to trigger and complete the Al-5.7wt.%Ni eutectic alloy formation, respectively. X-ray diffraction (XRD) was employed to determine the eutectic alloy powders formation progress as a function of MT and for the investigation of the internal structural evolution in terms of crystallite sizes and lattice strain induced by milling. Prolonged milling up to 40 h of MT resulted in changes in the powder morphology and produced nanocrystalline (NC) alloy powders about 20 nm in average crystallite size. Isothermal heating (ITH) of the milled loose powders at 500 °C for 60 min using differential scanning calorimetry (DSC) was employed for the evaluation of the thermal stability produced NC structure. Alloys milled up to the alloy complete formation time at intermediate milling energies of 300 RPM and 15:1 BPR displayed relatively higher structural stability against grain growth compared to the powders milled at higher milling energies. Prolonged MT strongly influenced the morphology of the eutectic structure, which had a negative impact on the structural stability against growth during heating for both the as milled powders and the hot compact discs.

The damage mechanisms associated with the deformation and failure of high-strength Al 2139-T8 were investigated by optical and scanning electron microscopy at strain rates ranging from the quasi-static, 10^(−3) s^(−1), to the high strain rate, at approximately 2350 s^(−1). Deformation was more uniform at the lowest strain rate of 10^(−3) s^(−1), where nanocracking nucleated at coarse inclusions and clustered dispersed particles. Deformation was more localized as the strain-rate increased, with microvoid nucleation, resulting from particle-matrix interfacial decohesion and particle cracking, observed at higher strain rates. Dispersed particles and coarse inclusions were observed on the fracture surfaces of the deformed samples subjected to high rates of strain. Coarse inclusions were associated with inclusion cracking and shear deformation. The dispersed particles were associated with dimpled rupture, and the orientation of the particles determined the amount of plasticity prior to failure of the alloy.

The Nile Delta aquifer in Egypt is among the largest groundwater reservoirs in the world. This paper presents main sources causing Fe and Mn pollution to nonconventional drainage and groundwater resources and an applied method to reduce both elements to be safe. The main environmental problems were analyzed to suggest an optimum solution to be implemented in Delta District, Egypt. Raw water samples were collected and analyzed from Gharbia Governorate's study area as it represents most Delta governorates. One of the main problems related to water in Delta is the reddish colour caused by the presence of ferrous and manganese. Iron and manganese concentrations in most samples exceeded World Health Organization and Egyptian Standard for safe water limits. Iron ranges between 0.1 & 1.33, while manganese shows 0.5 & 1.45 (mg/l) in the raw water, respectively. A (GIS) model was developed to access geostatistical analyst and mapping the probability that Fe and Mn concentration exceeds a critical threshold. Results show that the main polluting sources are from chemicals and fertilizers used in fruits farms as well from petrochemical and industrial activities. Treatment process is suggested with percentage removal of Fe & Mn exceeded 92% and 96% with residual concentrations less than 0.1 and 0.05 (mg/l), respectively. These values fulfil the Egyptian guidelines for safe water requirements.

Double-oxide films (bifilms) have been held responsible for the variability in mechanical properties of aluminum castings. It has been suggested that the air entrapped inside a bifilm can react with the surrounding melt, leading to its consumption, which might improve the mechanical properties of the castings. In this work the effect of holding the melt before solidification on the distribution of mechanical properties, and by implication on entrained double oxide films, was investigated for several different aluminum alloys. The Weibull moduli of plate castings were determined under tensile conditions, and their fracture surfaces were examined for evidence of oxide films. The results suggested the occurrence of two competing mechanisms during the holding treatment: (1) the consumption of air inside the bifilms by reaction with the surrounding molten metal that may lead to improvements in mechanical properties and (2) the accompanying diffusion of hydrogen into the bifilms, which would be expected to have a deleterious effect on properties.

Nano-crystalline W-1%Y(2)O(3) (wt.%) powder was produced by a modified solution chemical reaction of ammonium paratungstate (APT) and yttrium nitrate. The precursor powder was found to consist of p ...

High purity W and W-0.9La(2)O(3) (wt.%) nanopowders were produced by a wet chemical route. The precursor was prepared by the reaction of ammonium paratungstate (APT) with lanthanum salt in aqueous ...

Amorphous silicon carbide (SiC) thin films were deposited on silicon substrates by pulsed laser ablation at room temperature. Thicknesses and surface morphology of the thin films were characterized using optical profilers, atomic force and field emission scanning electron microscopy. Nanohardnes, modulus and scratch resistance properties were determined using XP nanoindenter. The results show that crack free, smooth and nanostructured thin films can be deposited using low laser energy densities.

Surface modification of engineering materials allows the production of far superior products in terms of reduced wear, increased corrosion resistance, better biocompatibility, and improved optical and altered electrical/electronic properties. Excimer laser annealing provides a rapid and efficient means for surface alloying and modification of ceramic materials. In this study, alumina–13% titania (AT-13) coatings were sprayed with a water-stabilized plasma spray gun. The coated surface was treated by excimer laser having a wavelength of 248 nm and pulse duration of 24 ns. The surface structure of the treated coating was examined by field emission scanning electron microscope and X-ray diffraction (XRD). A detailed parametric study was performed to investigate the effects of different parameters such as laser energy density (fluence), pulse repetition rate (PRR), and number of pulses on the mechanical properties, surface morphology, and microstructure of the coatings. The study reveals that the laser fluence plays a major role in modifying the surface morphology of the coating, followed by the pulse repetition rate.

AA2124 nanopowders

A detailed experimental and computational investigation of the influence of equal channel angular pressing (ECAP) on the microstructure and properties of precompacted 2124-Al nanostructured powder, canned in copper, was conducted. Measurements and observations were obtained by densitometry and optical, scanning, and transmission electron microscopy. Based on experimental observations, it was found that hot compacts subjected to a single ECAP pass had significant microstructural refinement and subgrain formation, and significant density changes were not attained. Green compacts, on the other hand, were observed to lose coherency under ECAP. Three-dimensional finite element modeling of the ECAP process was also conducted to further elucidate the evolution of the extrusion process, and to understand how it affects plastic strains, porosity, and thermal distributions.

L’auteur se fonde sur l’experience d’une consultation interdisciplinaire de la maltraitance intrafamiliale, avec une equipe de medecins, de psychologues et d’educateurs, tous d’orientation systemique (therapies familiales, de couple, individuelles ou de groupe, avec travail de reseau). Il decrit la strategie de la reconnaissance et du pardon en famille suite a des abus divers (sexuels, physiques, psychologiques, carentiels). La necessite de restaurer le lien familial compromis par l’abus requiert un travail patient et en settings tantot separes, tantot collectifs, selon une logique tenant compte du triangle auteur-victime-tiers. Les principes et les regles techniques de cette approche « pyramidale » sont exposes dans l’article, etayes par quelques vignettes cliniques. Il appert qu’il convient de ne pas perdre de vue l’importance de preserver l’ascendant du parent amene a reconnaitre ses mefaits et ademander pardon a l’enfant abuse, afin de restaurer le lien sans compromettre sa hierarchie naturelle (dans l’interet de l’enfant comme dans celui de la famille).

There are many non-linear interaction factors responsible for the performance of the laser cutting process. Identification of the dominant factors that significantly affect the cut quality is important. The present research aims to evaluate the CW ND:YAG laser cutting parameters (the gas pressure, laser power, and scanning speed) for 1.2 mm thick ultra-low carbon steel sheets. The effect of the cutting parameters on the cut quality was then investigated, by monitoring the variation in hardness, oxide layer width and microstructural changes within the heat affected zone (HAZ). Results revealed that good quality cuts can be produced in ultra low carbon steel thin sheets, at a window of laser scanning speed of 1100–1500 mm/min and at a minimum heat input of 337 W under an assisting O2 gas pressure of 5 bar. Higher laser power resulted in either strengthening or softening in the HAZ surrounding the cut kerfs. The oxide layer width is not affected by the energy density input, but is affected by the O2 gas pressure due to exothermal reaction.

In this paper AA2124/graphene self-lubricating nanocomposites with different graphene addition of 0.5,3 and 5%wt. were prepared using P/M technique. A combination of cold compaction and hot extrusion (H.E) at ~0.45Tm were employed for fabrication of the nanocomposites. Addition of graphene significantly increased the compressive strength and hardness of the composites, while poor results were obtained for the ductility at room temperature. The microstructures of the composites were studied using OM and SEM. The effects of graphene addition on the friction and wear performances of the nanocomposites at room temperature in air in sliding against plain AA 2124 were investigated for the HE conditions using a pin-on-disk tribometer. Results showed that the wear rates of AA21224 could be remarkably reduced when 3wt% graphene is added and when cold compaction followed by HE at relatively low temperature was employed.