Long Duration Persistent Photocurrent in 3 nm Thin Doped Indium Oxide for Integrated Light Sensing and In-Sensor Neuromorphic Computation

Miniaturization and energy consumption by computational systems remain major challenges to address. Optoelectronics based synaptic and light sensing provide an exciting platform for neuromorphic processing and vision applications offering several advantages. It is highly desirable to achieve single-element image sensors that allow reception of information and execution of in-memory computing processes while maintaining memory for much longer durations without the need for frequent electrical or optical rehearsals. In this work, ultra-thin (<3 nm) doped indium oxide (In₂O₃) layers are engineered to demonstrate a monolithic two-terminal ultraviolet (UV) sensing and processing system with long optical state retention operating at 50 mV. This endows features of several conductance states within the persistent photocurrent window that are harnessed to show learning capabilities and significantly reduce the number of rehearsals. The atomically thin sheets are implemented as a focal plane array (FPA) for UV spectrum based proof-of-concept vision system capable of pattern recognition and memorization required for imaging and detection applications. This integrated light sensing and memory system is deployed to illustrate capabilities for real-time, in-sensor memorization, and recognition tasks. This study provides an important template to engineer miniaturized and low operating voltage neuromorphic platforms across the light spectrum based on application demand.     

Genetic algorithm-based improved DOA estimation using fourth-order cumulants

Genetic algorithm (GA)-based direction of arrival (DOA) estimation is proposed using fourth-order cumulants (FOC) and ESPRIT principle which results in Multiple Invariance Cumulant ESPRIT algorithm. In the existing FOC ESPRIT formulations, only one invariance is utilised to estimate DOAs. The unused multiple invariances (MIs) must be exploited simultaneously in order to improve the estimation accuracy. In this paper, a fitness function based on a carefully designed cumulant matrix is developed which incorporates MIs present in the sensor array. Better DOA estimation can be achieved by minimising this fitness function. Moreover, the effectiveness of Newton’s method as well as GA for this optimisation problem has been illustrated. Simulation results show that the proposed algorithm provides improved estimation accuracy compared to existing algorithms, especially in the case of low SNR, less number of snapshots, closely spaced sources and high signal and noise correlation. Moreover, it is observed that the optimisation using Newton’s method is more likely to converge to false local optima resulting in erroneous results. However, GA-based optimisation has been found attractive due to its global optimisation capability.     

CMOS current feedback op amp-based chaos generators using novel active nonlinear voltage controlled resistors with odd symmetrical characteristics

Novel grounded and floating CMOS active nonlinear resistors with odd symmetrical characteristics are designed. The nonlinear resistors are then incorporated into two chaotic oscillator circuits based on a CMOS current feedback op amp (CFOA). The slopes of both the negative and positive segments of the nonlinear characteristics are voltage controlled, allowing for a wide range of dynamic behaviour to be observed and easily tuned in a period doubling route to chaos. Nonlinear current–voltage characteristics are derived in a piecewise-linear form and shown possibly to be modelled using a cubic polynomial approximation. PSPICE simulations using a standard 2.0 μm technology file and numerical simulations of the derived chaotic mathematical models are included.     

Organic geochemistry characterisation of crude oils from Mishrif reservoir rocks in the southern Mesopotamian Basin,South Iraq: Implication for source input and paleoenvironmental conditions

Seven crude oils from Cretaceous Mishrif reservoir rocks in the southern Mesopotamian Basin, South Iraq were studied to describe oil characteristics, providing information on the source of organic matter input and the genetic link between oils and their potential source rock in the basin. This study is based on biomarker and non-biomarker analyses performed on oil samples. The analysed oils are aromatic intermediate oils as indicated by high aromatic hydrocarbon fractions with more that 50%. These oils are also characterized by high sulfur and trace metal (Ni, V) contents and relatively low API gravity values (19.0–27.2° API). The results of this study indicate that these oils were derived from a marine carbonate source rocks bearing Type II-S kerogen that were deposited under sulphate-reducing conditions. This is primary achieved from their biomarkers and bulk carbon isotope and inorganic element contents (i.e., S, Ni and V). The absence of 18a (H)-oleanane biomarker also suggests a source age older than Late Cretaceous. The biomarker characteristics of these oils are consistent with those of the Late Jurassic to Early Cretaceous source rocks in the basin. However, biomarker maturity data also indicate that the oils were generated from early maturity source rocks. This appears to result from the type of kerogen of the source rock, characterized by a high-S kerogen (Type II-S).     

Vipulanandan model for the rheological properties with ultimate shear stress of oil well cement modified with nanoclay

In this study, the effect of clay nanoparticles (NC) and temperature on the rheological properties with ultimate shear stress and weight loss of the oil well cement (class H) modified with NC was investigated. The NC content was varied between 0 and 1% by the weight of the cement. The total weight loss at 800 °C for the oil well cement decreased from 6.10% to 1.03%, a 83% reduction when the cement was mixed with 1% of NC. The results also showed that 1% of NC increased the rheological properties of the cement slurry. The NC modification increased the yield stress (τ_o) and plastic viscosity (PV) by 5%–65% and 3%–16% respectively based on the NC content and the temperature of the cement slurry. The shear thinning behavior of the cement slurry with and without NC has been quantified using the Vipulanandan rheological model and compared with the Herschel-Bulkley model. The Vipulanandan rheological model has a maximum shear stress limit were as the Herschel-Bulkley model did not have a limit on the maximum shear stress. Based on the Vipulanandan rheological model the maximum shear stress produced by the 0% and 1% of NC at the temperature of 25 °C were 102 Pa and 117 Pa respectively hence an increase of 15% in the ultimate shear stress due to the addition of NC. The addition of 1% of NC increased the compressive strength of the cement by 12% and 43% after 1 day and 28 days of curing respectively. The modulus of elasticity of the cement increased with the additional of 1% NC by 6% and 76% after 1 day and 28 days of curing respectively. Effects of NC content and the temperature on the model parameters have been quantified using a nonlinear model (NLM). The NLM quantified the effect of NC treatment on all the model parameters.     

Bulk geochemical characteristics and carbon isotope composition of oils from the Sayhut sub-basin in the Gulf of Aden with emphasis on organic matter input,age and maturity

The Sayhut sub-basin is undergoing hydrocarbon exploration province in the Gulf of Aden, South Yemen. In this study, geochemical analyses were performed on three oil samples from two exploration wells in the Sayhut sub-basin. The results were used to describe the source organic matter input, age and maturity and to correlate between crude oils from different pay zones.The high saturated hydrocarbon values of more than 70% indicate that the analysed oils are normal crude oils and not degraded oils. This is supported by a complete suite of their normal alkanes and acyclic isoprenoids. The hydrocarbon distributions of normal alkane and isoprenoid with bulk carbon isotope data also suggest that the analysed oils are grouped into two genetic families and were generated from marine-source rock. The family A presents by one oil sample representing Harshiyat reservoir rock and characterized by relatively high Ph/Ph ratio > 2 and δ¹³C values of their saturated and aromatic hydrocarbon fractions range from ?26.1‰ to ?24.8‰. This oil family was derived from mixed organic matter with high contribution of a terrigenous organic matter input. The family A was deposited under suboxic conditions during the Late Cretaceous age. The family B presents by two oil samples representing Ghaydah and Habshiyah reservoir rocks and characterized by relatively low Ph/Ph ratio < 2 and carbon isotope less than ?23 for their saturated and aromatic hydrocarbon fractions. These oils were generated from source rock containing high contributions of marine organic matter (e.g., algal and microbial) with minor amount of land plant source inputs that was deposited in more reducing conditions. The family B oils are consistent with those of the Paleogene Umm Er Radhuma source rock.The hydrocarbon distribution and oil composition data also indicate that the analysed oils were generated from mature source rocks with a peak oil-window maturity.     

Treatment and restoration of used Mineral-Oil-Based hydraulic fluids from different machines. Part 1: Dewatering,filtration and effect of viscosity modifier

In this work, characterization and treatment of used hydraulic oil samples were performed in three steps. In the first step, the physical and the chemical properties of fresh and used hydraulic mineral oil samples from various centrifugal casting and pipe drawing machines were investigated according to ASTM D 6158. Results show that water content, solid particles count and depletion of additives have considerably affected most of the oil properties. Used oil samples failed in the appearance, thermal stability, oxidation stability, foaming tendency, water content and particles count.

In the second step, a simple methodology for dewatering and filtration was adopted. This methodology involved settling, followed by dry-air bubbling for oil dehydration and finally vacuum filtration. Such process successfully removed considerable portion of solid particles and water in used oil samples. Appearance, pour point, water content, particles count, and acid number were restored to the allowable limits. While water separability, oxidation stability, thermal stability and foaming tendency still failed the limits after treatment. It is obvious that additives will be needed to restore the latter properties.

In the third step, viscosity modifier additive was added to the oil samples to enhance viscous properties. A linear increase in kinematic viscosity was witnessed at 100°C, while at 40°C, an initial linear increase at low viscosities was followed by lower slopes at higher viscosities.     

Oxidative desulfurization using graphene and its composites for fuel containing thiophene and its derivatives: An update review

Oxidative desulfurization, in which the aromatic sulfur containing compounds are oxidized to their analogical sulfones and subsequently extracted, has assured to be one of the exceedingly effective desulfurization processes for resulting ultra-low sulfur import fuels. The oxidative desulfurization process using graphene oxide has attracted significant interest for sulfur removal from fuels. In this survey, we discussed systematically the techniques of desulfurizations in catalytic oxidation, including the role of graphene as a supported catalyst, the research results of oxidative desulfurization using graphene oxide and provided the factors affecting the desulfurization process. We also debate the challenges counterattack the use of graphene oxide in this view, including their preparation methods and their efficiency and stability as a supported catalyst. Also, there are some of the desulfurization processes currently under investigation such as oxidation, biodesulfurization, and adsorption was outlined in brief. The combustion of fossil fuels containing sulfur compounds emits some of the sulfur oxides which considered a harmful influence on human health and the surrounding environment as well as the economy. It can be concluded that GO remains a kind of ideal supported catalysts to recognize a pure fuel in the near futurity due to their eligible physicochemical characteristics.     

Azeotrope formation in gasoline–ethanol blends. Part 1 – Impact of nonionic on E10 distillation curve

Blending 10?vol% of ethanol into hydrocarbon base gasoline (HBG) increases significantly the vapour pressure of the blend (E10), and exhibits near-azeotrope behaviour that severely affects the shape of E10 distillation curve. The distillation curves of HBG and E10 fuel blend, were constructed using ASTM D86 distillation data, and the areas under each distillation curve, were calculated through the numerical trapezoid rule (NTR) and calculus definite integration (CDI) methods. Consequently, the area due to azeotrope formation (ADAF), was estimated. In this paper, we present the impact of small concentration of nonionic surfactant on the area under distillation curve (AUDC) of E10 fuel blend and the area due to azeotrope formation (ADAF). Also, the influences of the added surfactant on the volatility criteria of the investigated E10 fuel blend were discussed.