Reinforcement Components Research Articles

Animal models of drug addiction.

The development of animal models of drug reward and addiction is an essential factor for progress in understanding the biological basis of this disorder and for the identification of new therapeutic targets. Depending on the component of reward to be studied, one type of animal model or another may be used. There are models of reinforcement based on the primary hedonic effect produced by the consumption of the addictive substance, such as the self-administration (SA) and intracranial self-stimulation (ICSS) paradigms, and there are models based on the component of reward related to associative learning and cognitive ability to make predictions about obtaining reward in the future, such as the conditioned place preference (CPP) paradigm. In recent years these models have incorporated methodological modifications to study extinction, reinstatement and reconsolidation processes, or to model specific aspects of addictive behavior such as motivation to consume drugs, compulsive consumption or drug seeking under punishment situations. There are also models that link different reinforcement components or model voluntary motivation to consume (two-bottle choice, or drinking in the dark tests). In short, innovations in these models allow progress in scientific knowledge regarding the different aspects that lead individuals to consume a drug and develop compulsive consumption, providing a target for future treatments of addiction.

A novel design for reinforcing the aircraft tail leading edge structure against bird strike

This paper presents the work performed to design a novel tail leading edge structure by employing the finite element method coupled with the SPH method to simulate the bird strike process. The bird is simulated by the SPH model while the structure is modeled with the traditional Lagrangian elements. Bird strike experiments are conducted to validate the numerical model. Good agreements between simulation and experimental results showed that the coupled SPH-FE method provides a valid and effective means to predict the deformation and damage behavior of aircraft structures subjected to bird strike. Thus, it can be used as a tool to design bird strike-resistant structures. It is found that the novel design, which introduces a triangular reinforcement component to the leading edge structure, greatly enhances the anti-bird strike performance. Finally bird strike simulations and experiments are conducted for the Horizontal tail leading edge of a commercial aircraft with the above mentioned novel design. No penetration on the frontal beam is observed, suggesting that the novel design meet the certification requirement of CCAR part 25.

Creation of composite nanostructured surface-reinforced powder materials based on Ti/WC and Ti/TiCN used for coatings with enhanced hardness

The paper presents a new method of creating composite powder materials for protective coatings. The article investigates the dependence of the properties of coatings on the ratio of matrix and reinforcement components in powder compositions. The properties of the coatings and their practical applications as innovative reinforcing materials are studied, as well as unique compositions based on the Ti/WC and Ti/TiCN systems.

Bearing capacity of strip foundations in horizontal-vertical reinforced soils

The formula for calculating the ultimate bearing capacity of horizontal-vertical reinforced soil is investigated based on the failure mode and the mechanism of sand beds reinforced with horizontal-vertical reinforcement. Two components of soils and reinforcement are calculated separately. The ultimate bearing capacity of a shallow, concentrically loaded strip footing on homogeneous soil is commonly determined using the Terzaghi superposition method. The contribution of horizontal-vertical reinforcement is calculated based on the bearing resistance of the soil against the transverse members. A vertical inclusion is treated as a retaining wall, the confinement being calculated using Rankine's earth pressure theory. An analytical solution is presented including the traditional factors of soil, unit soil weight, footing width, number of horizontal-vertical reinforcement layers, and reinforcement geometry. The results were validated against experimental results and the mean error of the theoretical model was about 10%, with a maximum error of about 20%.

Experimental study on fatigue behavior of Steel Reinforced Concrete (SRC) beams

Steel reinforced concrete (SRC) beams have increasingly been adopted in civil engineering construction. There has been a paucity of studies on the fatigue behavior of SRC beams under high-cycle fatigue loading. To fill the knowledge gap in this area, this paper reports on an experimental investigation of SRC beams subjected to fatigue loading. Fatigue tests were carried out on 18 H-steel reinforced concrete beams and two pure H-steel beams. Key issues addressed in the paper include failure modes and failure sequences, crack initiation and crack propagation, as well as stiffness. The key parameters influencing the fatigue strength of SRC beams are identified, including the steel ratio of H-steel components, the steel reinforcement ratio of components and stud shear connectors. A comparison of fatigue behavior between H-steel components inside SRC beams and pure H-steel beams has been made. It seems that the fatigue failure modes of H-steel inside SRC beams are the same as those displayed by pure H-steel beams, but the former have significantly higher fatigue strength than the latter. Fatigue design (in terms of stress range – fatigue life (S-N curves)) is recommended for fatigue assessment of welded H-steel components and reinforcement components inside SRC beams, respectively.

Motivational shift: Effects of unrestricted and restricted feeding on wheel running as an operant and reinforcing consequence on a multiple schedule of reinforcement

Rats were exposed to a multiple schedule on which they pressed a lever on a variable-ratio schedule for wheel-running reinforcement in one component and ran a fixed number of revolutions for 15% sucrose solution reinforcement in the other component. Feeding was varied from restricted to unrestricted (ad-libitum) and then returned to restricted. Across these changes in feeding, average body weight varied from 262g to 339g to 258g. Under ad-lib feeding, wheel-running and lever-pressing rates decreased while postreinforcement pause duration increased in the wheel-running reinforcement component. In the operant wheel-running component, wheel-running rates also decreased and postreinforcement pause duration increased. Notably, wheel-running rates in the operant running component were higher than in the wheel-running reinforcement component when rats were food restricted, but did not differ when rats were freely fed, indicating a reduced effectiveness of sucrose reinforcement. This reduction in response strengthening of operant wheel running by sucrose under ad-libitum feeding is consistent with a shift from food-related to intrinsic motivation of running. From a response deprivation perspective (Allison & Timberlake, 1974), this reduced effectiveness of sucrose reinforcement would occur if wheel running in freely fed rats became the more constricted behavior in the contingency between instrumental wheel running and contingent sucrose consumption.

Numerical modeling of TRIP steel in axial crashworthiness

With their high strain rate hardening capacity and good combination of strength and ductility, transformation induced plasticity (TRIP) steels offer lightweight solutions for reinforcement components undergoing crash events. The TRIP effect correlates with stress-stimulated martensitic transformation from austenite, which depends on a myriad of kinematic ingredients, including three-dimensional plastic deformation, temperature change, strain-rate, and stress state. The complex interdependency of these kinematic ingredients requires stepwise and time iterative numerical analyses, especially when boundary-value problems are imposed. Typically engineering desired boundary value problems involve simulations designed to control energy absorption under complex crash scenarios. In this paper, we demonstrate a new phenomenological framework for thermo-mechanical modeling of multi-phase TRIP steel that captures the evolution of phase transformation. The model was implemented into the user-defined subroutine of the explicit dynamic version of the commercial finite element software LS-DYNA. Simulations were performed on a top-hat crush tube made of an industrial multiphase TRIP 800 steel. The results were utilized within an optimization simulation framework to pinpoint composition windows, which maximize the energy absorption capacity. When not concerned about peak crush force, larger compositions of austenite (typically ∼70%) will outperform all other compositions. However, lowering the austenite volume fraction with higher volume fractions of bainite (∼80%) with balanced ferrite could produce a top-hat crush rail with a superior crush force and efficiency compared to TRIP 800 steel without increasing the peak crush force.

Enhancement of toughness and wear resistance in boron nitride nanoplatelet (BNNP) reinforced Si3N4 nanocomposites.

Ceramics have superior hardness, strength and corrosion resistance, but are also associated with poor toughness. Here, we propose the boron nitride nanoplatelet (BNNP) as a novel toughening reinforcement component to ceramics with outstanding mechanical properties and high-temperature stability. We used a planetary ball-milling process to exfoliate BNNPs in a scalable manner and functionalizes them with polystyrene sulfonate. Non-covalently functionalized BNNPs were homogeneously dispersed with Si3N4 powders using a surfactant and then consolidated by hot pressing. The fracture toughness of the BNNP/Si3N4 nanocomposite increased by as much as 24.7% with 2 vol.% of BNNPs. Furthermore, BNNPs enhanced strength (9.4%) and the tribological properties (26.7%) of the ceramic matrix. Microstructural analyzes have shown that the toughening mechanisms are combinations of the pull-out, crack bridging, branching and blunting mechanisms.

Studies in Effect of Synthetic and Natural Microfibers on Properties of High-Density Polyethylene-Reinforced Composite

ABSTRACTNatural fibers are now arising as one of the promising reinforcement components for fiber-reinforced polymer composites. A study has been conducted to optimize weight concentration of surface-treated and surface-untreated microfibers on the properties of high-density polyethylene composite. Polyethylene terephthalate and henequen microfibers in varying compositions, namely, 1, 3, 5, 8, 10, and 20 wt% were reinforced into high-density polyethylene matrix. These fibers were treated with coupling agent at 0.5 wt%. Vinyltrimethoxysilane-treated composite shows enhanced properties as compared to untreated microfiber composite. Rheological and morphological results reveal that addition of coupling agent improves dispersion and matrix fiber interactions.

An evaluation of multiple-schedule variations to reduce high-rate requests in the picture exchange communication system.

Using procedures similar to those of Tiger, Hanley, and Heal (2006), we compared two multiple-schedule variations (S+/S- and S+ only) to treat high-rate requests for edible items in the Picture Exchange Communication System (PECS). Two individuals with autism participated, after they showed persistent requests for edible items after PECS training. Stimulus control was achieved only with the multiple schedule that involved presentation of a discriminative stimulus during reinforcement components and its removal during extinction components (S+ only). Discriminated requests were maintained for the 1 participant who experienced schedule thinning.

High Performance Cutting of Fibre Reinforced Plastic Composite Materials

Composite materials are difficult to machine because of the anisotropy and inhomogeneity of their microstructure and the abrasiveness of their reinforcement components. This low machinability can determine surface integrity damage in the machined parts and very rapid wear development in the cutting tool. To date, conventional machining processes, such as turning, drilling or milling, are increasingly required for composite materials parts manufacturing, and can be successfully applied if proper tool design is achieved and adequate machining conditions are selected. This paper presents an outline of the main issues pertaining the machining of fibre reinforced plastic composite materials.

Quantification of mechanical and hydric components of soil reinforcement by plant roots

The use of vegetation to stabilize slopes with regard to shallow landslides is an ecological and economic alternative to traditional solutions of civil engineering. This study aims at quantifying the effect of soil water content on the reinforcement of soil by plant roots and determines how soil water content influences the failure modes of roots during shear. Direct shear box tests were performed on three species used in hillslope reforestation programs in Yunnan, China. Reinforcement was quantified and divided into a hydric component corresponding to the effect of water removal and a mechanical component reflecting the influence of roots on apparent cohesion and friction angle. It was shown that the hydric component of reinforcement can be of the same order as the mechanical component and that root system architectural traits influence the type of mechanical reinforcement (cohesive or frictional). We also demonstrate the potential development of matric suction effects on the shear strength of soil.

Mechanical, thermal and acoustical characterizations of an insulation composite made of bio-based materials

Heating costs in winter and cooling costs in summer, nowadays, are very high and these costs a can be reduced by the insulation of buildings. This study is related to the development of bio-based composites and the determination of their thermal, mechanical and acoustical insulation properties. The composites were prepared using corn stalk particles as the reinforcement components. An experimental design was established to study the effect of the stalk particle size and the epoxy/corn stalk particle ratio on the thermal and mechanical properties of the composites prepared. Their mechanical properties and thermal performance characteristics are compared with the commercially available bio-based insulation materials.This study shows that waste corn-on-the-cob can be used for the reinforcement of epoxy resin to prepare insulation materials that can be used commercially. Natural products of high insulating value can be obtained that can provide alternative insulation materials and reduce the import of insulation materials and satisfy the criteria of the Turkish Standard TS 805 EN 601. The results of this study can solve two industrial problems. One of them is providing a new useful construction material and the other is utilizing agricultural wastes to reduce their harm to the environment.

Life Cycle Assessment of Vehicle Lightweighting: Novel Mathematical Methods to Estimate Use-Phase Fuel Consumption.

Lightweighting is a key strategy to improve vehicle fuel economy. Assessing the life-cycle benefits of lightweighting requires a quantitative description of the use-phase fuel consumption reduction associated with mass reduction. We present novel methods of estimating mass-induced fuel consumption (MIF) and fuel reduction values (FRVs) from fuel economy and dynamometer test data in the U.S. Environmental Protection Agency (EPA) database. In the past, FRVs have been measured using experimental testing. We demonstrate that FRVs can be mathematically derived from coast down coefficients in the EPA vehicle test database avoiding additional testing. MIF and FRVs calculated for 83 different 2013 MY vehicles are in the ranges 0.22-0.43 and 0.15-0.26 L/(100 km 100 kg), respectively, and increase to 0.27-0.53 L/(100 km 100 kg) with powertrain resizing to retain equivalent vehicle performance. We show how use-phase fuel consumption can be estimated using MIF and FRVs in life cycle assessments (LCAs) of vehicle lightweighting from total vehicle and vehicle component perspectives with, and without, powertrain resizing. The mass-induced fuel consumption model is illustrated by estimating lifecycle greenhouse gas (GHG) emission benefits from lightweighting a grille opening reinforcement component using magnesium or carbon fiber composite for 83 different vehicle models.

The influence of grouting and reinforcement ratio in the concrete block masonry compressive behavior

This paper presents an experimental investigation on the compressive strength and stress-strain curves of concrete block masonry with varying block and grout strengths and reinforcement ratio. The three-block prisms, built with 8.5 and 15.0 MPa blocks, were tested hollow and filled with 17.0 and 30.0 MPa compressive strength grouts. In addition, prisms and walls with reinforcement rates of 0.15%, 0.40% and 1.0 % were also tested. With the results, it was possible to measure the compressive strength and stress-strain behavior of masonry with inclusion of different grout and reinforcement components, giving parameters for better evaluation of their performance and design. Among the conclusions, it was observed that increasing the compressive strength of masonry is not proportional to the increase of the grouting area and the efficiency of reinforcement to increase compressive strength is low. Stress-strain curves for the several materials combinations are made available.

Evaluation of Flexible Li4Ti5O12 Anode Electrodes Using Water-Based Binder for Li-Ion Batteries

Li-ion batteries are today essential for portable electronic devices as a main power source. Flexible Li-ion batteries have attracted great attention and could be very useful in the emerging fields of flexible, wearable, implantable and bendable electronic devices. Nano-fibrillated cellulose (NFC), with a high aspect ratio (length/diameter) of the nanofibrils, has shown to be a promising binder material for flexible Li-ion batteries [i] [ii]. As a reinforcement component, it gives flexible electrodes good mechanical properties. In addition, the process of making the flexible electrodes is water-based, eliminating the toxicity problem of using conventional poly(vinylidene fluoride) (PVDF) as binder. However, capacity fading limits the stability of the flexible electrodes during repeated cycling. Side reactions on the graphite negative electrodes could be the reason for the capacity loss. Li4Ti5O12(LTO), with a high potential of 1.55 V versus Li metal, could be an alternative to graphite for flexible negative electrodes, reducing the reactivity with the electrolyte. In this work, the electrochemical performance, such as specific capacity and columbic efficiency (CE), and mechanical properties of flexible LTO anode electrodes using NFC as binder are investigated. Fig 1 shows the photograph of LTO electrode, illustrating the flexibility. Fig. 1 Photograph of flexible Li4Ti5O12 negative electrode. [i] S.Leijonmarck, et al. Flexible nano-paper-based positive electrodes for Li-ion batteries-Preparation process and properties, Nano Energy, 2013, 2, 794–800. [ii] S.Leijonmarck, et al. Single-paper flexible Li-ion battery cells through a paper-making process based on nano-fibrillated cellulose, Journal of Materials Chemistry A, 2013, 1, 4671-4677. Figure 1

Effect of sucrose availability on wheel-running as an operant and as a reinforcing consequence on a multiple schedule: Additive effects of extrinsic and automatic reinforcement

As a follow up to Belke and Pierce’s (2014) study, we assessed the effects of repeated presentation and removal of sucrose solution on the behavior of rats responding on a two-component multiple schedule. Rats completed 15 wheel turns (FR 15) for either 15% or 0% sucrose solution in the manipulated component and lever pressed 10 times on average (VR 10) for an opportunity to complete 15 wheel turns (FR 15) in the other component. In contrast to our earlier study, the components advanced based on time (every 8min) rather than completed responses. Results showed that in the manipulated component wheel-running rates were higher and the latency to initiate running longer when sucrose was present (15%) compared to absent (0% or water); the number of obtained outcomes (sucrose/water), however, did not differ with the presentation and withdrawal of sucrose. For the wheel-running as reinforcement component, rates of wheel turns, overall lever-pressing rates, and obtained wheel-running reinforcements were higher, and postreinforcement pauses shorter, when sucrose was present (15%) than absent (0%) in manipulated component. Overall, our findings suggest that wheel-running rate regardless of its function (operant or reinforcement) is maintained by automatically generated consequences (automatic reinforcement) and is increased as an operant by adding experimentally arranged sucrose reinforcement (extrinsic reinforcement). This additive effect on operant wheel-running generalizes through induction or arousal to the wheel-running as reinforcement component, increasing the rate of responding for opportunities to run and the rate of wheel-running per opportunity.

Harmine treatment enhances short-term memory in old rats: Dissociation of cognition and the ability to perform the procedural requirements of maze testing

Harmine is a naturally occurring monoamine oxidase inhibitor that has recently been shown to selectively inhibit the dual-specificity tyrosine-(Y)-phosphorylation-regulated kinase 1A (DYRK1A). We investigated the cognitive effects of 1mg (low) Harmine and 5mg (high) Harmine using the delayed-match-to-sample (DMS) asymmetrical 3-choice water maze task to evaluate spatial working and recent memory, and the Morris water maze task (MM) to test spatial reference memory. Animals were also tested on the visible platform task, a water-escape task with the same motor, motivational, and reinforcement components as the other tasks used to evaluate cognition, but differing in its greater simplicity and that the platform was visible above the surface of the water. A subset of the Harmine-high treated animals showed clear motor impairments on all behavioral tasks, and the visible platform task confirmed a lack of competence to perform the procedural components of water maze testing. After excluding animals from the high dose group that could not perform the procedural components of a swim task, it was revealed that both high- and low-dose treatment with Harmine enhanced performance on the latter portion of DMS testing, but had no effect on MM performance. Thus, this study demonstrates the importance of confirming motor and visual competence when studying animal cognition, and verifies the one-day visible platform task as a reliable measure of ability to perform the procedural components necessary for completion of a swim task.

Decreasing excessive functional communication responses while treating destructive behavior using response restriction.

Functional communication training (FCT) is an established treatment for destructive behavior that missucceeds in about 37% of cases when the reinforcement schedule for the functional communication response (FCR) is thinned using multiples schedules (mult FCT; Hagopian, Boelter, & Jarmolowicz, 2011). In this investigation, we evaluated the use of response restriction FCT (RR FCT) in a cohort of patients with poorly differentiated responding of the FCR during mult FCT. Results showed that (a) RR FCT maintained high rates of correct FCRs during the reinforcement component of RR FCT without increasing destructive behavior; (b) children displayed highly discriminated FCRs when an FCR card and a control card were simultaneously available during the reinforcement component of RR FCT; and (c) near-zero rates of destructive behavior were observed during the last five sessions of the terminal reinforcement schedule. Results are discussed relative to differences between mult FCT and RR FCT and successive and simultaneous discriminations.

The Effects of a Multiple Schedule Plus Rules on Hand Raising During Circle Time in Preschool Classrooms

Preschool and kindergarten teachers expect children to sit appropriately and attend to the teacher during group instruction. However, children may engage in high rates of inappropriate responses that distract other students from learning opportunities. In addition, children often receive intermittent teacher attention for inappropriate responses, which might result in a lack of discrimination for when attention is or is not available. The purpose of the current study was to assess the efficacy of a multiple schedule plus rules indicative of the availability of attention for hand raises during circle time in typical preschool classrooms. Results showed that the rates of hand raises increased or maintained in the reinforcement component and decreased in the extinction component of the multiple schedule in all three classrooms. Results suggest that a multiple schedule plus rules indicative of the availability of attention from a classroom teacher can be used by preschool teachers in typical classrooms to maintain hand raise responses at appropriate levels.