Beyond Positive Reinforcement: OBM as a Humanizing Approach to Management Practices

Science.gov (United States)

Crowell, Charles R.

2005-01-01

This article comments on the need to recognize that OBM already is a "positive psychology" for many more reasons than just that it embraces positive reinforcement as a cornerstone of workplace improvement. This paper suggests there are at least 10 ways in which OBM constitutes a distinctly "positive" and humanizing approach to management…

Group Systematic Desensitization Versus Covert Positive Reinforcement in the Reduction of Test Anxiety

Science.gov (United States)

Kostka, Marion P.; Galassi, John P.

1974-01-01

The study compared modified versions of systematic desensitization and covert positive reinforcement to a no-treatment control condition in the reduction of test anxiety. On an anagrams performance test, the covert reinforcement and control groups were superior to the desensitization group. (Author)

Application of the Durability Reinforcement Technique on the Frame Structure

International Nuclear Information System (INIS)

Kwon, Sung Hun; Yoo, Hong Hee

2009-01-01

In this paper, the technique to reinforce the durability performance of structure using the sensitivity information for the frame structure is applied. The fatigue life calculation for the frame structure is performed from the quasi-static and transient analysis and the characteristics of two methods are compared for the fatigue analysis. Then the reinforcement technique is applied. First, some design variables related to the locations of fatigue failure is selected. Then sensitivities of fatigue life at fracture points with respect to the variation of design variables are calculated and the vector composed of gaps between the target life and initial life cycles is calculated. If the number of fatigue fracture points is same as the number of design variables, the variations of the design variables are calculated from the linear algebraic equation. If not, the variations of the design variables are calculated from the optimization formulation with the constraints

Preparation of curcumin nanoparticle by using reinforcement ionic gelation technique

Science.gov (United States)

Suryani, Halid, Nur Hatidjah Awaliyah; Akib, Nur Illiyyin; Rahmanpiu, Mutmainnah, Nina

2017-05-01

Curcumin, a polyphenolic compound present in curcuma longa has a wide range of activities including anti-inflammatory properties. The potency of curcumin is limited by its poor oral bioavailability because of its poor solubility in aqueous. Various methods have been tried to solve the problem including its encapsulation into nanoparticle. The aim of this study is to develop curcumin nanoparticle by using reinforcement ionic gelation technique and to evaluate the stability of curcumin nanoparticles in gastrointestinal fluid. Curcumin nanoparticles were prepared by using reinforcement ionic gelation technique with different concentrations of chitosan, trypolyphosphate, natrium alginate and calcium chloride. Curcumin nanoparticles were then characterized including particle size and zeta potential by using particle size analyzer and morphology using a transmission electron microscope, entrapment efficiency using UV-Vis Spectrophotometer and chemical structure analysis by Infra Red Spectrophotometer (FTIR). Furthermore, the stability of curcumin nanoparticles were evaluated on artificial gastric fluid and artificial intestinal fluids by measuring the amount of curcumin released in the medium at a time interval. The result revealed that curcumin nanoparticles can be prepared by reinforcement ionic gelation technique, the entrapment efficiency of curcumin nanoparticles were from 86.08 to 91.41%. The average of particle size was 272.9 nm and zeta potential was 12.05 mV. The morphology examination showed that the curcumin nanoparticles have spherical shape. The stability evaluation of curcumin nanoparticles showed that the nanoparticles were stable on artificial gastric fluid and artificial intestinal fluid. This result indicates that curcumin nanoparticles have the potential to be developed for oral delivery.

Positive behavioral contrast across food and alcohol reinforcers.

OpenAIRE

McSweeney, F K; Melville, C L; Higa, J

1988-01-01

The present study examined behavioral contrast during concurrent and multiple schedules that provided food and alcohol reinforcers. Concurrent-schedule contrast occurred in the responding reinforced by food when alcohol reinforcers were removed. It also occurred in the responding reinforced by alcohol when food was removed. Multiple-schedule contrast appeared for food when alcohol reinforcers were removed, but not for alcohol when food was removed. These results show that behavioral contrast ...

Emphasizing the 'positive' in positive reinforcement: Using non-binary rewarding for training monkeys on cognitive tasks.

Science.gov (United States)

Fischer, Benjamin; Wegener, Detlef

2018-04-04

Non-human primates constitute an indispensable model system for studying higher brain func-tions at the neurophysiological level. Studies involving these animals elucidated the neuronal mechanisms of various cognitive and executive functions, such as visual attention, working memory, and decision-making. Positive Reinforcement Training (PRT) constitutes the gold standard for training animals on the cognitive tasks employed in these studies. In the laboratory, PRT is usually based on applying a liquid reward as the reinforcer to strengthen the desired be-havior, and absence of the reward if the animal's response was wrong. By trial-and-error, the monkey may adopt its behavior and successfully reduces the number of error trials, and eventu-ally learns even very sophisticated tasks. However, progress and success of the training strongly depend on reasonable error rates. If errors get too frequent, they may cause a drop in the ani-mal's motivation to cooperate, or its adaptation to high error rates and poor overall perfor-mance. We here introduce an alternative training regime to minimize errors and base the critical information for learning on graded rewarding. For every new task rule, the feedback to the ani-mal is provided by different amounts of reward to distinguish the desired, optimal behavior from less optimally behavior. We applied this regime in different situations during training of visual attention tasks, and analyzed behavioral performance and reaction times to evaluate its effec-tiveness. For both simple and complex behaviors, graded rewarding was found to constitute a powerful technique allowing for effective training without trade-off in accessible task difficulty or task performance.

Effectiveness of an educational video as an instrument to refresh and reinforce the learning of a nursing technique: a randomized controlled trial.

Science.gov (United States)

Salina, Loris; Ruffinengo, Carlo; Garrino, Lorenza; Massariello, Patrizia; Charrier, Lorena; Martin, Barbara; Favale, Maria Santina; Dimonte, Valerio

2012-05-01

The Undergraduate Nursing Course has been using videos for the past year or so. Videos are used for many different purposes such as during lessons, nurse refresher courses, reinforcement, and sharing and comparison of knowledge with the professional and scientific community. The purpose of this study was to estimate the efficacy of the video (moving an uncooperative patient from the supine to the lateral position) as an instrument to refresh and reinforce nursing techniques. A two-arm randomized controlled trial (RCT) design was chosen: both groups attended lessons in the classroom as well as in the laboratory; a month later while one group received written information as a refresher, the other group watched the video. Both groups were evaluated in a blinded fashion. A total of 223 students agreed to take part in the study. The difference observed between those who had seen the video and those who had read up on the technique turned out to be an average of 6.19 points in favour of the first (P video were better able to apply the technique, resulting in a better performance. The video, therefore, represents an important tool to refresh and reinforce previous learning.

Developing and implementing a positive behavioral reinforcement intervention in prison-based drug treatment: Project BRITE.

Science.gov (United States)

Burdon, William M; St De Lore, Jef; Prendergast, Michael L

2011-09-01

Within prison settings, the reliance on punishment for controlling inappropriate or noncompliant behavior is self-evident. What is not so evident is the similarity between this reliance on punishment and the use of positive reinforcements to increase desired behaviors. However, seldom do inmates receive positive reinforcement for engaging in prosocial behaviors or, for inmates receiving drug treatment, behaviors that are consistent with or support their recovery. This study provides an overview of the development and implementation of a positive behavioral reinforcement intervention in male and female prison-based drug treatment programs. The active involvement of institutional staff, treatment staff, and inmates enrolled in the treatment programs in the development of the intervention along with the successful branding of the intervention were effective at promoting support and participation. However, these factors may also have ultimately impacted the ability of the randomized design to reliably demonstrate the effectiveness of the intervention.

Improved Sectional Image Analysis Technique for Evaluating Fiber Orientations in Fiber-Reinforced Cement-Based Materials.

Science.gov (United States)

Lee, Bang Yeon; Kang, Su-Tae; Yun, Hae-Bum; Kim, Yun Yong

2016-01-12

The distribution of fiber orientation is an important factor in determining the mechanical properties of fiber-reinforced concrete. This study proposes a new image analysis technique for improving the evaluation accuracy of fiber orientation distribution in the sectional image of fiber-reinforced concrete. A series of tests on the accuracy of fiber detection and the estimation performance of fiber orientation was performed on artificial fiber images to assess the validity of the proposed technique. The validation test results showed that the proposed technique estimates the distribution of fiber orientation more accurately than the direct measurement of fiber orientation by image analysis.

[Exploration of acupoint combination and needling techniques in the reinforcing and reducing manipulation at different acupoints].

Science.gov (United States)

Dai, Qing; Sheng, Xiesun; Chen, Feng

2017-04-12

The reinforcing and reducing manipulation at different acupoints is a kind of acupuncture manipulations and has satisfactory clinical therapeutic effects, combined with a proper needling techniques. The reinforcing needling method is used in the upper and the reducing one in the lower, the distal acupoints are combined with the nearby acupoints. The local acupoints or adjcant acupoints of the affected area are regarded as the nearby acupoints, e.g. the acupoints in the upper. The distant acupoints and the acupoints on the hand and foot are named as distal acupoints, e.g. the acupoint in the lower. In the reinforcing manipulation, the needle is inserted shallowly along the running direction of meridian. In the reducing manipulation, the needle is inserted deeply and against the running direction of meridian. The yin - yang couple needling technique is used with the combination of the front- mu and back- shu points. In the first option, the reinforcing and reducing needling method with rotating technique is predominated at the front- mu points, while that with lifting and thrusting technique is at the back- shu points. In the second option, when needling the back- shu points, the needling sensation is transmitted along the transverse segment and far to the chest and abdomen. These two kinds of integration of acupoint combination and needling techniques display a certain clinical significance in improving the therapeutic effects of acupuncture.

Glass Fiber Reinforced Polymer (GFRP Bars for Enhancing the Flexural Performance of RC Beams Using Side-NSM Technique

Directory of Open Access Journals (Sweden)

Md. Akter Hosen

2017-05-01

Full Text Available Reinforced concrete (RC structures require strengthening for numerous factors, such as increased load, modification of the structural systems, structural upgrade or errors in the design and construction stages. The side near-surface mounted (SNSM strengthening technique with glass fiber-reinforced polymer (GFRP bars is a relatively new emerging technique for enhancing the flexural capacities of existing RC elements. Nine RC rectangular beams were flexurally strengthened with this technique and tested under four-point bending loads until failure. The main goal of this study is to optimize the structural capacity of the RC beams by varying the amount of strengthening reinforcement and bond length. The experimental test results showed that strengthening with SNSM GFRP bars significantly enhanced the flexural responses of the specimens compared with the control specimen. The first cracking and ultimate loads, energy absorption capacities, ductility and stiffness were remarkably enhanced by the SNSM technique. It was also confirmed that the bond length of the strengthened reinforcement greatly influences the energy absorption capacities, ductility and stiffness. The effect of the bond length on these properties is more significant compared to the amount of strengthening reinforcement.

A Study on Nondestructive Technique Using Laser Technique for Evaluation of Carbon fiber Reinforced Plastic

International Nuclear Information System (INIS)

Choi, Sang Woo; Lee, Joon Hyun; Seo, Kyeong Cheol; Byun, Joon Hyung

2005-01-01

Fiber reinforced plastic material should be inspected in fabrication process in order to enhance quality by prevent defects such as delamination and void. Generally, ultrasonic technique is widely used to evaluate FRP. In conventional ultrasonic techniques, transducer should be contacted on FRP. However, conventional contacting method could not be applied in fabrication process and novel non-contact evaluating technique was required. Laser-based ultrasonic technique was tried to evaluate CFRP plate. Laser-based ultrasonic waves propagated on CFRP were received with various transducers such as accelerometer and AE sensor in order to evaluate the properties of waves due to the variation of frequency. Velocities of laser-based ultrasonic waves were evaluated for various fiber orientation. In addition, laser interferometry was used to receive ultrasonic wave in CFRP and frequency was analysed

Evidence for positive, but not negative, behavioral contrast with wheel-running reinforcement on multiple variable-ratio schedules.

Science.gov (United States)

Belke, Terry W; Pierce, W David

2016-12-01

Rats responded on a multiple variable-ratio (VR) 10 VR 10 schedule of reinforcement in which lever pressing was reinforced by the opportunity to run in a wheel for 30s in both the changed (manipulated) and unchanged components. To generate positive contrast, the schedule of reinforcement in the changed component was shifted to extinction; to generate negative contrast, the schedule was shifted to VR 3. With the shift to extinction in the changed component, wheel-running and local lever-pressing rates increased in the unchanged component, a result supporting positive contrast; however, the shift to a VR 3 schedule in the changed component showed no evidence of negative contrast in the unaltered setting, only wheel running decreased in the unchanged component. Changes in wheel-running rates across components were consistent in showing a compensation effect, depending on whether the schedule manipulation increased or decreased opportunities for wheel running in the changed component. These findings are the first to demonstrate positive behavioral contrast on a multiple schedule with wheel running as reinforcement in both components. Copyright © 2016 Elsevier B.V. All rights reserved.

Application of Fiber Reinforcement Concrete Technique in Civil ...

African Journals Online (AJOL)

modulus of elasticity, high tensile strength, improved fatigue and impact resistance. Reinforcing the concrete structures with fibers such as polyester is one of the possible ways to provide all the criteria of the durable repair material. This type of reinforcement is called Fiber Reinforcement of Concrete Structures. There is an ...

Employment-based abstinence reinforcement following inpatient detoxification in HIV-positive opioid and/or cocaine-dependent patients

OpenAIRE

Dunn, Kelly; Fingerhood, Michael; Wong, Conrad J.; Svikis, Dace S.; Nuzzo, Paul; Silverman, Kenneth

2014-01-01

Employment-based reinforcement interventions have been used to promote abstinence from drugs among chronically unemployed injection drug users. The current study utilized an employment-based reinforcement intervention to promote opiate and cocaine abstinence among opioid-dependent, HIV-positive participants who had recently completed a brief inpatient detoxification. Participants (n=46) were randomly assigned to an Abstinence & Work group that was required to provide negative urine samples in...

How should periods without social interaction be scheduled? Children's preference for practical schedules of positive reinforcement.

Science.gov (United States)

Luczynski, Kevin C; Hanley, Gregory P

2014-01-01

Several studies have shown that children prefer contingent reinforcement (CR) rather than yoked noncontingent reinforcement (NCR) when continuous reinforcement is programmed in the CR schedule. Preference has not, however, been evaluated for practical schedules that involve CR. In Study 1, we assessed 5 children's preference for obtaining social interaction via a multiple schedule (periods of fixed-ratio 1 reinforcement alternating with periods of extinction), a briefly signaled delayed reinforcement schedule, and an NCR schedule. The multiple schedule promoted the most efficient level of responding. In general, children chose to experience the multiple schedule and avoided the delay and NCR schedules, indicating that they preferred multiple schedules as the means to arrange practical schedules of social interaction. In Study 2, we evaluated potential controlling variables that influenced 1 child's preference for the multiple schedule and found that the strong positive contingency was the primary variable. © Society for the Experimental Analysis of Behavior.

Aggression as Positive Reinforcement in People with Intellectual Disabilities

Science.gov (United States)

May, Michael E.

2011-01-01

From an applied behavior-analytic perspective, aggression in people with intellectual disabilities is mostly maintained by social reinforcement consequences. However, nonsocial consequences have also been identified in functional assessments on aggression. Behaviors producing their own reinforcement have been labeled "automatic" or "nonsocial" in…

An automated system for positive reinforcement training of group-housed macaque monkeys at breeding and research facilities.

Science.gov (United States)

Tulip, Jennifer; Zimmermann, Jonas B; Farningham, David; Jackson, Andrew

2017-06-15

Behavioural training through positive reinforcement techniques is a well-recognised refinement to laboratory animal welfare. Behavioural neuroscience research requires subjects to be trained to perform repetitions of specific behaviours for food/fluid reward. Some animals fail to perform at a sufficient level, limiting the amount of data that can be collected and increasing the number of animals required for each study. We have implemented automated positive reinforcement training systems (comprising a button press task with variable levels of difficulty using LED cues and a fluid reward) at the breeding facility and research facility, to compare performance across these different settings, to pre-screen animals for selection and refine training protocols. Animals learned 1- and 4-choice button tasks within weeks of home enclosure training, with some inter-individual differences. High performance levels (∼200-300 trials per 60min session at ∼80% correct) were obtained without food or fluid restriction. Moreover, training quickly transferred to a laboratory version of the task. Animals that acquired the task at the breeding facility subsequently performed better both in early home enclosure sessions upon arrival at the research facility, and also in laboratory sessions. Automated systems at the breeding facility may be used to pre-screen animals for suitability for behavioural neuroscience research. In combination with conventional training, both the breeding and research facility systems facilitate acquisition and transference of learning. Automated systems have the potential to refine training protocols and minimise requirements for food/fluid control. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Reinforcement of the pelvic diaphragm using a purse-string suture in dogs: description of technique

Directory of Open Access Journals (Sweden)

P.C. Moraes

Full Text Available ABSTRACT Recurrence of perineal hernias is frequent, and is associated to poor identification of anatomical structures during surgery, inadequate suture placement, and failure of physical support of the pelvic diaphragm after surgical reconstruction. The objective of this work is to describe a novel surgical technique for reinforcement of the pelvic diaphragm after performing the internal obturator transposition technique in dogs with perineal hernia.

Pharmacological stimuli decreasing nucleus accumbens dopamine can act as positive reinforcers but have a low addictive potential.

Science.gov (United States)

Marinelli, M; Barrot, M; Simon, H; Oberlander, C; Dekeyne, A; Le Moal, M; Piazza, P V

1998-10-01

Opioid peptides, through mu and delta receptors, play an important part in reward. In contrast, the role of kappa receptors is more controversial. We examined the possible positive reinforcing effects of a selective kappa agonist, RU 51599, by studying intravenous self-administration in the rat. The effect of RU 51599 on dopamine release in the nucleus accumbens was also studied, as opioids and dopamine seem to interact in the mediation of reward. The behavioural and dopaminergic effects of RU 51599 were compared with those of the mu agonist heroin. Rats self-administered both RU 51599 (6.5, 20 and 60 microg/inj) and heroin (30 microg/inj) at low ratio requirement. When the ratio requirement, i.e. the number of responses necessary to receive one drug infusion, was increased, self-administration of RU 51599 rapidly extinguished, whereas self-administration of heroin was maintained. Intravenous infusion of RU 51599 (100, 200 and 400 microg) dose-dependently decreased (25, 30 and 40%, respectively) extracellular concentrations of dopamine, as measured by means of microdialysis in freely moving rats. In contrast, heroin increased accumbens dopamine (130% over baseline). These results indicate that kappa receptors, similarly to mu ones, can mediate positive reinforcing effects of opioid peptides. However, the strength of the reinforcement is very low for kappa receptors. This suggests that changes in accumbens dopamine do not correlate with the capacity of a stimulus to induce reward or aversion. In contrast, a parallel seems to exist between an increase in accumbens dopamine and the drive to reach or obtain a positive reinforcer.

Hunger neurons drive feeding through a sustained, positive reinforcement signal.

Science.gov (United States)

Chen, Yiming; Lin, Yen-Chu; Zimmerman, Christopher A; Essner, Rachel A; Knight, Zachary A

2016-08-24

The neural mechanisms underlying hunger are poorly understood. AgRP neurons are activated by energy deficit and promote voracious food consumption, suggesting these cells may supply the fundamental hunger drive that motivates feeding. However recent in vivo recording experiments revealed that AgRP neurons are inhibited within seconds by the sensory detection of food, raising the question of how these cells can promote feeding at all. Here we resolve this paradox by showing that brief optogenetic stimulation of AgRP neurons before food availability promotes intense appetitive and consummatory behaviors that persist for tens of minutes in the absence of continued AgRP neuron activation. We show that these sustained behavioral responses are mediated by a long-lasting potentiation of the rewarding properties of food and that AgRP neuron activity is positively reinforcing. These findings reveal that hunger neurons drive feeding by transmitting a positive valence signal that triggers a stable transition between behavioral states.

Performance of Reinforced Concrete Beam with Differently Positioned Replacement Zones of Block Infill under Low Impact Loads

Directory of Open Access Journals (Sweden)

Mokhatar Shahrul Niza

2017-01-01

Full Text Available This paper reveals a study performed on reinforced concrete with artificial aggregate concrete block infill composite beams to innovate a lightweight reinforced concrete utilizing polyethylene (PE waste materials, such as waste plastic bags. Six beam specimens of normal reinforced concrete (NRC and different block infill replacement zone positions RCAI (RZ1 beams containing 100% MAPEA with 50, 95, and 1,000 mm width, height, and length, respectively, were provided for the block infill, whereas RCAI (RZ2 with different block infill positions containing a 100% MAPEA with 50, 115, and 1000 mm width, height, and length were provided and tested under low impact load. The steel impactor with blunt nose dropped at 0.6 m height which equivalent to 3.5 m/s. The behaviors of the beams were studied relative to the impact force-time and displacement-time histories, the flexural/ bending cracks, and the impact failure. Results show that the overall failure modes of all the beam specimens were successfully recorded. In addition, the residual displacements of the RZ2 was almost same than those of the RZ1 and the significantly lower than those of the NRC. In the reinforced concrete beams, less stressed concrete near the neutral axis can be replaced by certain light weight material like waste plastic bags as modified artificial polyethylene aggregates to serve as an artificial aggregate.

Research on corrosion detection for steel reinforced concrete structures using the fiber optical white light interferometer sensing technique

International Nuclear Information System (INIS)

Zhao, Xuefeng; Cui, Yanjun; Kong, Xianglong; Wei, Heming; Zhang, Pinglei; Sun, Changsen

2013-01-01

In this paper, a novel kind of steel rebar corrosion monitoring technique for steel reinforced concrete structures is proposed, designed, and tested. The technique is based on the fiber optical white light interferometer (WLI) sensing technique. Firstly, a feasibility test was carried out using an equal-strength beam for comparison of strain sensing ability between the WLI and a fiber Bragg grating (FBG). The comparison results showed that the sensitivity of the WLI is sufficient for corrosion expansion strain monitoring. Then, two WLI corrosion sensors (WLI-CSs) were designed, fabricated, and embedded into concrete specimens to monitor expansion strain caused by steel rebar corrosion. Their performance was studied in an accelerated electrochemical corrosion test. Experimental results show that expansion strain along the fiber optical coil winding area can be detected and measured accurately by the proposed sensor. The advantages of the proposed monitoring technique allow for quantitative corrosion expansion monitoring to be executed in real time for reinforced concrete structures and with low cost. (paper)

Evidence for an involvement of 5-hydroxytryptaminergic neurones in the maintenance of operant behaviour by positive reinforcement.

Science.gov (United States)

Wogar, M A; Bradshaw, C M; Szabadi, E

1991-01-01

The possible involvement of the ascending 5-hydroxytryptaminergic (5HTergic) pathways in the maintenance of operant behaviour by positive reinforcement was examined using a quantitative paradigm based on Herrnstein's (1970) equation which defines a hyperbolic relationship between steady-state response rate and reinforcement frequency in variable-interval schedules. Nine rats received injections of 5,7-dihydroxytryptamine into the dorsal and median raphe nuclei; 12 rats received sham injections. The rats were trained to steady-state in a series of variable-interval schedules of sucrose reinforcement affording a range of reinforcement frequencies. Herrnstein's equation was fitted to the data obtained from each rat and to the averaged data obtained from the two groups. The value of KH (the parameter expressing the reinforcement frequency needed to obtain the half-maximum response rate) was significantly lower in the lesioned group than in the control group; the values of Rmax (the parameter expressing the maximum response rate) did not differ significantly between the two groups. The levels of 5HT and 5-hydroxyindoleacetic acid in the parietal cortex, hippocampus, nucleus accumbens and hypothalamus were markedly reduced in all four regions in the lesioned group, but the levels of noradrenaline and dopamine were not significantly affected. The results indicate that damage to the central 5HTergic pathways resulted in an increase in the "value" of the sucrose reinforcer, without affecting the animals' response capacity. The results are consistent with the suggestion that the 5HTergic pathways may exert some limiting control on the "values" of certain reinforcers.

Reinforcement Schedules in a Verbal Reinforcement Combination and Renection-Impulsivity

OpenAIRE

TAMASE, Koji; UEDA, Masako

1986-01-01

It was predicted that higher proportion of the negative reinforcement "Wrong" than that of the positive reinforcement "Right" in a reinforcement combination will produce higher proportion of the correct response and this trend will be greater in reflective children than in impulsive children. From 140 kindergarten children 30 reflective and 30 impulsive children were selected and they were given a two-hole marble-dropping task. The best performance in the ratio of correct responses was obtain...

Rats bred for helplessness exhibit positive reinforcement learning deficits which are not alleviated by an antidepressant dose of the MAO-B inhibitor deprenyl.

Science.gov (United States)

Schulz, Daniela; Henn, Fritz A; Petri, David; Huston, Joseph P

2016-08-04

Principles of negative reinforcement learning may play a critical role in the etiology and treatment of depression. We examined the integrity of positive reinforcement learning in congenitally helpless (cH) rats, an animal model of depression, using a random ratio schedule and a devaluation-extinction procedure. Furthermore, we tested whether an antidepressant dose of the monoamine oxidase (MAO)-B inhibitor deprenyl would reverse any deficits in positive reinforcement learning. We found that cH rats (n=9) were impaired in the acquisition of even simple operant contingencies, such as a fixed interval (FI) 20 schedule. cH rats exhibited no apparent deficits in appetite or reward sensitivity. They reacted to the devaluation of food in a manner consistent with a dose-response relationship. Reinforcer motivation as assessed by lever pressing across sessions with progressively decreasing reward probabilities was highest in congenitally non-helpless (cNH, n=10) rats as long as the reward probabilities remained relatively high. cNH compared to wild-type (n=10) rats were also more resistant to extinction across sessions. Compared to saline (n=5), deprenyl (n=5) reduced the duration of immobility of cH rats in the forced swimming test, indicative of antidepressant effects, but did not restore any deficits in the acquisition of a FI 20 schedule. We conclude that positive reinforcement learning was impaired in rats bred for helplessness, possibly due to motivational impairments but not deficits in reward sensitivity, and that deprenyl exerted antidepressant effects but did not reverse the deficits in positive reinforcement learning. Copyright © 2016 IBRO. Published by Elsevier Ltd. All rights reserved.

Fatigue damage monitoring for basalt fiber reinforced polymer composites using acoustic emission technique

Science.gov (United States)

Wang, Wentao; Li, Hui; Qu, Zhi

2012-04-01

Basalt fiber reinforced polymer (BFRP) is a structural material with superior mechanical properties. In this study, unidirectional BFRP laminates with 14 layers are made with the hand lay-up method. Then, the acoustic emission technique (AE) combined with the scanning electronic microscope (SEM) technique is employed to monitor the fatigue damage evolution of the BFRP plates in the fatigue loading tests. Time-frequency analysis using the wavelet transform technique is proposed to analyze the received AE signal instead of the peak frequency method. A comparison between AE signals and SEM images indicates that the multi-frequency peaks picked from the time-frequency curves of AE signals reflect the accumulated fatigue damage evolution and fatigue damage patterns. Furthermore, seven damage patterns, that is, matrix cracking, delamination, fiber fracture and their combinations, are identified from the time-frequency curves of the AE signals.

Study of positioning techniques for radiography

International Nuclear Information System (INIS)

Maruyama, Toshinori; Yamamoto, Hideki

2008-01-01

A good positioning technique is of great importance in radiology in order to obtain accurate diagnostic information and reduce the patient's X-ray exposure. In positioning training, students place the phantom on the table under an X-ray tube, adjust the position of the phantom, and repeat the positioning practices until they can obtain fine diagnostic images. As X-ray films are usually used in radiography, the development of such films is necessary. In this kind of training practice, it takes a great deal of time to obtain the X-ray image at the phantom position. It is desirable for students to perform positioning accurately and to confirm the results of positioning within a short time. In this article, we propose a new positioning training method using digital image processing. First, we scan the skull phantom by CT (computed tomography) and obtain CT images. Next, we measure the positioning information of the phantom under the X-ray equipment by using scene analysis. Then, we develop a method that produces the plane image corresponding to the detected phantom position under the X-ray tube. It is expected that our method will be useful as a teaching device to help in the practice of the positioning techniques for various organs without X-ray exposure and, furthermore, in the development of X-ray films. (author)

A simple stir casting technique for the preparation of in situ Fe-aluminides reinforced Al-matrix composites

Directory of Open Access Journals (Sweden)

Susanta K. Pradhan

2016-09-01

Full Text Available This article presents a simple stir casting technique for the development of Fe-aluminides particulate reinforced Al-matrix composites. It has been demonstrated that stirring of super-heated Al-melt by a mild steel plate followed by conventional casting and hot rolled results in uniform dispersion of in situ Al13Fe4 particles in the Al matrix; the amount of reinforcement is found to increase with increasing melt temperature. With reference to base alloy, the developed composite exhibits higher hardness and improved tensile strength without much loss of ductility; since, composite like base alloy undergoes ductile mode of fracture.

Continuous Reinforced Concrete Beams

DEFF Research Database (Denmark)

Hoang, Cao Linh; Nielsen, Mogens Peter

1996-01-01

This report deals with stress and stiffness estimates of continuous reinforced concrete beams with different stiffnesses for negative and positive moments e.g. corresponding to different reinforcement areas in top and bottom. Such conditions are often met in practice.The moment distribution...

Arthroscopic Double-Row Transosseous Equivalent Rotator Cuff Repair with a Knotless Self-Reinforcing Technique.

Science.gov (United States)

Mook, William R; Greenspoon, Joshua A; Millett, Peter J

2016-01-01

Rotator cuff tears are a significant cause of shoulder morbidity. Surgical techniques for repair have evolved to optimize the biologic and mechanical variables critical to tendon healing. Double-row repairs have demonstrated superior biomechanical advantages to a single-row. The preferred technique for rotator cuff repair of the senior author was reviewed and described in a step by step fashion. The final construct is a knotless double row transosseous equivalent construct. The described technique includes the advantages of a double-row construct while also offering self reinforcement, decreased risk of suture cut through, decreased risk of medial row overtensioning and tissue strangulation, improved vascularity, the efficiency of a knotless system, and no increased risk for subacromial impingement from the burden of suture knots. Arthroscopic knotless double row rotator cuff repair is a safe and effective method to repair rotator cuff tears.

Mathematical modeling of deformation of reinforced femur during prolonged static loads

Directory of Open Access Journals (Sweden)

Vladimir P. Radchenko

2015-12-01

Full Text Available A two-layer mathematical model of a human femur neck reinforced implants of different design for modeling stress-strain state which occurs during a surgical procedure to prevent femur neck fractures by the forced introduction of metallic implants is proposed. Engineered implant designs are provided. Methods and software for geometric modeling of femur embedded with the implants are developed. New boundary value problems to evaluate kinetics in creep conditions of the stress-strain state of reinforced and non-reinforced femoral neck during prolonged static loads corresponding to human foot traffic are formulated. Effective elastic properties of cortical and cancellous bone, power and kinematic boundary value problems. A phenomenological creep model for compact bone tissue is constructed. The technique of identifying the parameters is developed. A check of its adequacy to experimental data is carried out. Based on the finite element method the numerical method for solving the provided boundary value problems at macro level of continuum mechanics is developed. A lot of variative calculations allowed developing recommendations for the rational positioning of the implant in order to minimize stress concentrations. The performed analysis showed that there is a significant relaxation of stresses in the most loaded areas due to creep. Relaxation is more intense in reinforced femoral neck than in the unreinforced. Thus the tension in the most loaded femoral neck area due to creep is reduced by 49 % with respect to the intensity of the initial time of loading for femur which is reinforced by the spoke-spoke-type implant when loading duration is 1 year under natural loads corresponding to human foot traffic. It was found that the time component (long-term fixed load does not impair the positive effect of reducing the stress concentration due to a femoral neck reinforcement which is a positive fact from the medical practice point of view.

Brain network response underlying decisions about abstract reinforcers.

Science.gov (United States)

Mills-Finnerty, Colleen; Hanson, Catherine; Hanson, Stephen Jose

2014-12-01

Decision making studies typically use tasks that involve concrete action-outcome contingencies, in which subjects do something and get something. No studies have addressed decision making involving abstract reinforcers, where there are no action-outcome contingencies and choices are entirely hypothetical. The present study examines these kinds of choices, as well as whether the same biases that exist for concrete reinforcer decisions, specifically framing effects, also apply during abstract reinforcer decisions. We use both General Linear Model as well as Bayes network connectivity analysis using the Independent Multi-sample Greedy Equivalence Search (IMaGES) algorithm to examine network response underlying choices for abstract reinforcers under positive and negative framing. We find for the first time that abstract reinforcer decisions activate the same network of brain regions as concrete reinforcer decisions, including the striatum, insula, anterior cingulate, and VMPFC, results that are further supported via comparison to a meta-analysis of decision making studies. Positive and negative framing activated different parts of this network, with stronger activation in VMPFC during negative framing and in DLPFC during positive, suggesting different decision making pathways depending on frame. These results were further clarified using connectivity analysis, which revealed stronger connections between anterior cingulate, insula, and accumbens during negative framing compared to positive. Taken together, these results suggest that not only do abstract reinforcer decisions rely on the same brain substrates as concrete reinforcers, but that the response underlying framing effects on abstract reinforcers also resemble those for concrete reinforcers, specifically increased limbic system connectivity during negative frames. Copyright © 2014 Elsevier Inc. All rights reserved.

Using modeling and vicarious reinforcement to produce more positive attitudes toward mental health treatment.

Science.gov (United States)

Buckley, Gary I; Malouff, John M

2005-05-01

In this study, the authors evaluated the effectiveness of a video, developed for this study and using principles of cognitive learning theory, to produce positive attitudinal change toward mental health treatment. The participants were 35 men and 45 women who were randomly assigned to watch either an experimental video, which included 3 positive 1st-person accounts of psychotherapy or a control video that focused on the psychological construct of self. Pre-intervention, post-intervention, and 2-week follow-up levels of attitude toward mental health treatment were measured using the Attitude Toward Seeking Professional Help Scale (E. H. Fischer & J. L. Turner, 1970). The experimental video group showed a significantly greater increase in positive attitude than did the control group. These results support the effectiveness of using the vicarious reinforcement elements of cognitive learning theory as a basis for changing attitudes toward mental health treatment.

Void detection beneath reinforced concrete sections: The practical application of ground-penetrating radar and ultrasonic techniques

Science.gov (United States)

Cassidy, Nigel J.; Eddies, Rod; Dods, Sam

2011-08-01

Ground-penetrating radar (GPR) and ultrasonic 'pulse echo' techniques are well-established methods for the imaging, investigation and analysis of steel reinforced concrete structures and are important civil engineering survey tools. GPR is, arguably, the more widely-used technique as it is suitable for a greater range of problem scenarios (i.e., from rebar mapping to moisture content determination). Ultrasonic techniques are traditionally associated with the engineering-based, non-destructive testing of concrete structures and their integrity analyses (e.g., flaw detection, shear/longitudinal velocity determination, etc). However, when used in an appropriate manner, both techniques can be considered complementary and provide a unique way of imaging the sub-surface that is suited to a range of geotechnical problems. In this paper, we present a comparative study between mid-to-high frequency GPR (450 MHz and 900 MHz) and array-based, shear wave, pulse-echo ultrasonic surveys using proprietary instruments and conventional GPR data processing and visualisation techniques. Our focus is the practical detection of sub-metre scale voids located under steel reinforced concrete sections in realistic survey conditions (e.g., a capped, relict mine shaft or vent). Representative two-dimensional (2D) sections are presented for both methods illustrating the similarities/differences in signal response and the temporal-spatial target resolutions achieved with each technique. The use of three-dimensional data volumes and time slices (or 'C-scans') for advanced interpretation is also demonstrated, which although common in GPR applications is under-utilised as a technique in general ultrasonic surveys. The results show that ultrasonic methods can perform as well as GPR for this specific investigation scenario and that they have the potential of overcoming some of the inherent limitations of GPR investigations (i.e., the need for careful antenna frequency selection and survey design in

Anatomic deltoid ligament repair with anchor-to-post suture reinforcement: technique tip.

Science.gov (United States)

Lack, William; Phisitkul, Phinit; Femino, John E

2012-01-01

The deltoid ligament is the primary ligamentous stabilizer of the ankle joint. Both superficial and deep components of the ligament can be disrupted with a rotational ankle fracture, chronic ankle instability, or in late stage adult acquired flatfoot deformity. The role of deltoid ligament repair in these conditions has been limited and its contribution to arthritis is largely unknown. Neglect of the deltoid ligament in the treatment of ankle injuries may be due to difficulties in diagnosis and lack of an effective method for repair. Most acute repair techniques address the superficial deltoid ligament with direct end-to-end repair, fixation through bone tunnels, or suture anchor repair of avulsion injuries. Deep deltoid ligament repair has been described using direct end-to-end repair with sutures, as well as by autograft and allograft tendon reconstruction utilizing various techniques. Newer tenodesis techniques have been described for late reconstruction of both deep and superficial components in patients with stage 4 adult acquired flatfoot deformity. We describe a technique that provides anatomic ligament-to-bone repair of the superficial and deep bundles of the deltoid ligament while reducing the talus toward the medial malleolar facet of the tibiotalar joint with anchor-to-post reinforcement of the ligamentous repair. This technique may protect and allow the horizontally oriented fibers of the deep deltoid ligament to heal with the appropriate resting length while providing immediate stability of the construct.

Effects of partial reinforcement and time between reinforced trials on terminal response rate in pigeon autoshaping.

Science.gov (United States)

Gottlieb, Daniel A

2006-03-01

Partial reinforcement often leads to asymptotically higher rates of responding and number of trials with a response than does continuous reinforcement in pigeon autoshaping. However, comparisons typically involve a partial reinforcement schedule that differs from the continuous reinforcement schedule in both time between reinforced trials and probability of reinforcement. Two experiments examined the relative contributions of these two manipulations to asymptotic response rate. Results suggest that the greater responding previously seen with partial reinforcement is primarily due to differential probability of reinforcement and not differential time between reinforced trials. Further, once established, differences in responding are resistant to a change in stimulus and contingency. Secondary response theories of autoshaped responding (theories that posit additional response-augmenting or response-attenuating mechanisms specific to partial or continuous reinforcement) cannot fully accommodate the current body of data. It is suggested that researchers who study pigeon autoshaping train animals on a common task prior to training them under different conditions.

Axial Compression Tests on Corroded Reinforced Concrete Columns Consolidated with Fibre Reinforced Polymers

Directory of Open Access Journals (Sweden)

Bin Ding

2017-06-01

Full Text Available Reinforced concrete structure featured by strong bearing capacity, high rigidity, good integrity, good fire resistance, and extensive applicability occupies a mainstream position in contemporary architecture. However, with the development of social economy, people need higher requirements on architectural structure; durability, especially, has been extensively researched. Because of the higher requirement on building material, ordinary reinforced concrete structure has not been able to satisfy the demand. As a result, some new materials and structures have emerged, for example, fibre reinforced polymers. Compared to steel reinforcement, fibre reinforced polymers have many advantages, such as high tensile strength, good durability, good shock absorption, low weight, and simple construction. The application of fibre reinforced polymers in architectural structure can effectively improve the durability of the concrete structure and lower the maintenance, reinforcement, and construction costs in severe environments. Based on the concepts of steel tube concrete, fibre reinforced composite material confined concrete, and fibre reinforced composite material tubed concrete, this study proposes a novel composite structure, i.e., fibre reinforced composite material and steel tube concrete composite structure. The structure was developed by pasting fibre around steel tube concrete and restraining core concrete using fibre reinforced composite material and steel tubes. The bearing capacity and ultimate deformation capacity of the structure was tested using column axial compression test.

Reinforcement of Conducting Silver-based Materials

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Heike JUNG

2014-09-01

Full Text Available Silver is a well-known material in the field of contact materials because of its high electrical and thermal conductivity. However, due to its bad mechanical and switching properties, silver alloys or reinforcements of the ductile silver matrix are required. Different reinforcements, e. g. tungsten, tungsten carbide, nickel, cadmium oxide or tin oxide, are used in different sectors of switches. To reach an optimal distribution of these reinforcements, various manufacturing techniques (e. g. powder blending, preform infiltration, wet-chemical methods, internal oxidation are being used for the production of these contact materials. Each of these manufacturing routes offers different advantages and disadvantages. The mechanical alloying process displays a successful and efficient method to produce particle-reinforced metal-matrix composite powders. This contribution presents the obtained fine disperse microstructure of tungsten-particle-reinforced silver composite powders produced by the mechanical alloying process and displays this technique as possible route to provide feedstock powders for subsequent consolidation processes. DOI: http://dx.doi.org/10.5755/j01.ms.20.3.4889

Nondestructive Determination of Reinforcement Volume Fractions in Particulate Composites : Ultrasonic Method

International Nuclear Information System (INIS)

Jeong, Hyun Jo

1998-01-01

A nondestructive ultrasonic technique is presented for estimating the reinforcement volume fractions of particulate composites. The proposed technique employs a theoretical model which accounts for composite microstructures, together with a measurement of ultrasonic velocity to determine the reinforcement volume fractions. The approach is used for a wide range of SiC particulate reinforced Al matrix (SiC p /AI) composites. The method is considered to be reliable in determining the reinforcement volume fractions. The technique could be adopted in a production unit for the quality assessment of the metal matrix particulate composite extrusions

Performance of Hydrophobisation Techniques in Case of Reinforced Concrete Structures

Science.gov (United States)

Błaszczyński, Tomasz; Osesek, Mateusz; Gwozdowski, Błażej; Ilski, Mirosław

2017-10-01

Concrete is, unchangeably, one of the most frequently applied building materials, also in the case of bridges, overpasses or viaducts. Along with the aging of such structures, the degradation of concrete, which may accelerate the corrosion of reinforcing steel and drastically decrease the load-bearing capacity of the structure, becomes an important issue. The paper analyzes the possibilities of using deep hydrophobisation in repairing reinforced concrete engineering structures. The benefits of properly securing reinforced concrete structures from the damaging effects of UV radiation, the influence of harmful gases, or progression of chlorine induced corrosion have been presented, especially in regards to bridge structures. The need to calculate the costs of carrying out investments along with the expected costs of maintaining such structures, as well as the high share of costs connected with logistics, has also been indicated in the total costs of repair works.

Shape and Reinforcement Optimization of Underground Tunnels

Science.gov (United States)

Ghabraie, Kazem; Xie, Yi Min; Huang, Xiaodong; Ren, Gang

Design of support system and selecting an optimum shape for the opening are two important steps in designing excavations in rock masses. Currently selecting the shape and support design are mainly based on designer's judgment and experience. Both of these problems can be viewed as material distribution problems where one needs to find the optimum distribution of a material in a domain. Topology optimization techniques have proved to be useful in solving these kinds of problems in structural design. Recently the application of topology optimization techniques in reinforcement design around underground excavations has been studied by some researchers. In this paper a three-phase material model will be introduced changing between normal rock, reinforced rock, and void. Using such a material model both problems of shape and reinforcement design can be solved together. A well-known topology optimization technique used in structural design is bi-directional evolutionary structural optimization (BESO). In this paper the BESO technique has been extended to simultaneously optimize the shape of the opening and the distribution of reinforcements. Validity and capability of the proposed approach have been investigated through some examples.

Habituation of reinforcer effectiveness

Directory of Open Access Journals (Sweden)

David R Lloyd

2014-01-01

Full Text Available In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE that links behavioral and neural based explanations of reinforcement. We argue that habituation of reinforcer effectiveness (HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009;Rankin et al., 2009. We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect ‘accelerated-HRE’. Consideration of HRE is important for the development of effective reinforcement based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior.

Habituation of reinforcer effectiveness.

Science.gov (United States)

Lloyd, David R; Medina, Douglas J; Hawk, Larry W; Fosco, Whitney D; Richards, Jerry B

2014-01-09

In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE) that links behavioral- and neural-based explanations of reinforcement. We argue that HRE is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We argue that repeated presentation of reinforcing stimuli decreases their effectiveness and that these decreases are described by the behavioral characteristics of habituation (McSweeney and Murphy, 2009; Rankin etal., 2009). We describe a neural model that postulates a positive association between dopamine neurotransmission and HRE. We present evidence that stimulant drugs, which artificially increase dopamine neurotransmission, disrupt (slow) normally occurring HRE and also provide evidence that stimulant drugs have differential effects on operant responding maintained by reinforcers with rapid vs. slow HRE rates. We hypothesize that abnormal HRE due to genetic and/or environmental factors may underlie some behavioral disorders. For example, recent research indicates that slow-HRE is predictive of obesity. In contrast ADHD may reflect "accelerated-HRE." Consideration of HRE is important for the development of effective reinforcement-based treatments. Finally, we point out that most of the reinforcing stimuli that regulate daily behavior are non-consumable environmental/social reinforcers which have rapid-HRE. The almost exclusive use of consumable reinforcers with slow-HRE in pre-clinical studies with animals may have caused the importance of HRE to be overlooked. Further study of reinforcing stimuli with rapid-HRE is needed in order to understand how habituation and reinforcement interact and regulate behavior.

Analysis of tribological behaviour of zirconia reinforced Al-SiC hybrid composites using statistical and artificial neural network technique

Science.gov (United States)

Arif, Sajjad; Tanwir Alam, Md; Ansari, Akhter H.; Bilal Naim Shaikh, Mohd; Arif Siddiqui, M.

2018-05-01

The tribological performance of aluminium hybrid composites reinforced with micro SiC (5 wt%) and nano zirconia (0, 3, 6 and 9 wt%) fabricated through powder metallurgy technique were investigated using statistical and artificial neural network (ANN) approach. The influence of zirconia reinforcement, sliding distance and applied load were analyzed with test based on full factorial design of experiments. Analysis of variance (ANOVA) was used to evaluate the percentage contribution of each process parameters on wear loss. ANOVA approach suggested that wear loss be mainly influenced by sliding distance followed by zirconia reinforcement and applied load. Further, a feed forward back propagation neural network was applied on input/output date for predicting and analyzing the wear behaviour of fabricated composite. A very close correlation between experimental and ANN output were achieved by implementing the model. Finally, ANN model was effectively used to find the influence of various control factors on wear behaviour of hybrid composites.

Treatment of Escape-Maintained Behavior with Positive Reinforcement: The Role of Reinforcement Contingency and Density

Science.gov (United States)

Ingvarsson, Einar T.; Hanley, Gregory P.; Welter, Katherine M.

2009-01-01

Functional analyses suggested that the disruptive behavior of three preschool children was maintained by escape from demands. While keeping the escape contingency intact, we conducted (a) a density analysis in which the children earned preferred items for task completion according to two schedules that varied in reinforcement density, and (b) a…

Reinforced concrete tomography; Tomografia de hormigon armado

Energy Technology Data Exchange (ETDEWEB)

Mariscotti, M A.J.; Morixe, M; Tarela, P A; Thieberger, P [Tomografia de Hormigon Armado S.A., Boulogne (Argentina)

1998-12-31

In this paper we describe the technique of reinforced concrete tomography, its historical background, recent technological developments and main applications. Gamma radiation sensitive plates are imprinted with radiation going through the concrete sample under study, and then processed to reveal the presence of reinforcement and defects in the material density. The three dimensional reconstruction, or tomography, of the reinforcement out of a single gammagraphy is an original development alternative to conventional methods. Re-bar diameters and positions may be determined with an accuracy of {+-} 1 mm 0.5-1 cm, respectively. The non-destructive character of this technique makes it particularly attractive in cases of inhabited buildings and diagnoses of balconies. (author) 8 refs., 12 figs. [Espanol] En este trabajo se describe la tecnica de tomografia de hormigon armado, sus antededentes, recientes desarrollos y aplicaciones mas importantes. Esta tecnica se basa en el uso de radiacion gamma para penetrar piezas de hormigon. Placas gammagraficas son sensibilizadas con la radiacion que atraviesa la pieza bajo estudio y luego procesadas para revelar la presencia de armadura e inhomogeneidades en la densidad del concreto. La reconstruccion tridimensional o tomografia, de la armadura a partir de una sola gammagrafia es un desarrollo original alternativo a los metodos convencionales. Diametros y posiciones de los hierros existentes en el interior de columnas, vigas y losas pueden ser determinados con precisiones de {+-} 1 mm y 0.5-1 cm, respectivamente. La condicion de no destructiva hace que esta tecnica sea particularmente apreciada en los casos de edificios habitados y sea insustituible para el diagnostico de balcones. (autor)

The use of positive reinforcement in training zebra sharks (Stegostoma fasciatum).

Science.gov (United States)

Marranzino, Ashley

2013-01-01

Positive reinforcement training (PRT) was used on 4 adult zebra sharks, Stegostoma fasciatum, housed at the Downtown Aquarium, Denver, to determine the ability of zebra sharks to become desensitized to various stimuli associated with veterinary procedures. One male and 3 female sharks were trained for 12 weeks. As a result of PRT, all 4 zebra sharks were desensitized to staying within a closed holding tank off of the main exhibit, the presence of multiple trainers in the closed holding tank, and tactile stimulation. One of the 4 zebra sharks was also successfully desensitized to the presence of a stretcher being brought into the holding tank. All of these procedures are common in veterinary examinations, and it is hoped that desensitization to these stimuli will reduce the stress associated with examinations. The training accomplished has allowed for easier maintenance of the zebra sharks by the aquarium staff and an improvement in the care of the sharks.

Fracture resistance of metal-free composite crowns-effects of fiber reinforcement, thermal cycling, and cementation technique.

Science.gov (United States)

Lehmann, Franziska; Eickemeyer, Grit; Rammelsberg, Peter

2004-09-01

The improved mechanical properties of contemporary composites have resulted in their extensive use for the restoration of posterior teeth. However, the influence of fiber reinforcement, cementation technique, and physical stress on the fracture resistance of metal-free crowns is unknown. This in vitro study evaluated the effect of fiber reinforcement, physical stress, and cementation methods on the fracture resistance of posterior metal-free Sinfony crowns. Ninety-six extracted human third molars received a standardized tooth preparation: 0.5-mm chamfer preparation and occlusal reduction of 1.3 to 1.5 mm. Sinfony (nonreinforced crowns, n=48) and Sinfony-Vectris (reinforced crowns, n=48) crowns restoring original tooth contour were prepared. Twenty-four specimens of each crown type were cemented, using either glass ionomer cement (GIC) or resin cement. Thirty-two crowns (one third) were stored in humidity for 48 hours. Another third was exposed to 10,000 thermal cycles (TC) between 5 degrees C and 55 degrees C. The remaining third was treated with thermal cycling and mechanical loading (TCML), consisting of 1.2 million axial loads of 50 N. The artificial crowns were then vertically loaded with a steel sphere until failure occurred. Significant differences in fracture resistance (N) between experimental groups were assessed by nonparametric Mann-Whitney U-test (alpha=.05). Fifty percent of the Sinfony and Sinfony-Vectris crowns cemented with glass ionomer cement loosened after thermal cycling. Thermal cycling resulted in a significant reduction in the mean fracture resistance for Sinfony crowns cemented with GIC, from 2037 N to 1282 N (P=.004). Additional fatigue produced no further effects. Fiber reinforcement significantly increased fracture resistance, from 1555 N to 2326 N (P=.001). The minimal fracture resistance was above 600 N for all combinations of material, cement and loading. Fracture resistance of metal-free Sinfony crowns was significantly increased by

Influence of reinforcement on strains within maxillary implant overdentures.

Science.gov (United States)

Takahashi, Toshihito; Gonda, Tomoya; Maeda, Yoshinobu

2015-01-01

The purpose of this study was to examine the influence of reinforcement of an embedded cast on the strains within maxillary implant overdentures. A maxillary edentulous model with implants placed bilaterally in the canine positions, dome-shaped copings, and experimental overdentures was fabricated. Rosette-type strain gauges were attached in the canine positions and at three points along the midline of the polished surface of the denture and connected to the sensor interface controlled by a personal computer. Experimental dentures with five different reinforcements were tested: without reinforcement; with a cast cobalt-chrome reinforcement over the residual ridge and the tops of the copings; with the same reinforcement from first molar to first molar, over the residual ridge and the tops of the copings; with the same reinforcement over the residual ridge and the sides of the copings; and with the same reinforcement from first molar to first molar, over the residual ridge and the sides of the copings. A vertical occlusal load of 49 N was applied to the first premolar and then to the first molar, and the strains were measured and compared by analysis of variance. In both loading situations, significantly less strain was recorded in dentures with reinforcement than in those without reinforcement. When the first premolar was loaded on dentures with and without palatal reinforcement at the first premolars, the strains on the denture with reinforcement over the tops of the copings were significantly lower than on the denture with reinforcement over the sides of the copings at the canine position. Cast reinforcement over the residual ridge and the top of copings embedded in an acrylic base reduced the strain from occlusal stress on maxillary implant overdentures.

Diagnostics of glass fiber reinforced polymers and comparative analysis of their fabrication techniques with the use of acoustic emission

Science.gov (United States)

Bashkov, O. V.; Bryansky, A. A.; Panin, S. V.; Zaikov, V. I.

2016-11-01

Strength properties of the glass fiber reinforced polymers (GFRP) fabricated by vacuum and vacuum autoclave molding techniques were analyzed. Measurements of porosity of the GFRP parts manufactured by various molding techniques were conducted with the help of optical microscopy. On the basis of experimental data obtained by means of acoustic emission hardware/software setup, the technique for running diagnostics and forecasting the bearing capacity of polymeric composite materials based on the result of three-point bending tests has been developed. The operation principle of the technique is underlined by the evaluation of the power function index change which takes place on the dependence of the total acoustic emission counts versus the loading stress.

Marketing Animal-Friendly Products: Addressing the Consumer Social Dilemma with Reinforcement Positioning Strategies.

Science.gov (United States)

van Riemsdijk, Lenka; Ingenbleek, Paul T M; van Trijp, Hans C M; van der Veen, Gerrita

2017-12-14

This article presents a conceptual framework that aims to encourage consumer animal-friendly product choice by introducing positioning strategies for animal-friendly products. These strategies reinforce the animal welfare with different types of consumption values and can therefore reduce consumers' social dilemma, which is a major barrier to animal-friendly consumer choices. The article suggests how animal-friendly products can use various types of consumption values (functional, sensory, emotional, social, epistemic and situational) to create an attractive position relative to their competitors. It also explains why some consumer segments, such as those with a specific thinking style, may experience a stronger effect of some strategies, giving directions on how to approach different types of consumers. Finally, building on research asserting that animal welfare is a credence product attribute, the article proposes moderating effects of two factors that help consumers to evaluate the credibility of animal welfare claims, namely corporate social responsibility strategy and the role of stakeholders. Here it concludes that companies selling animal-friendly products need to be aware of the impact of their overall strategy on the effectiveness of positioning strategies for individual products and that, to gain consumer trust, they may need to collaborate with relevant stakeholders, such as media or animal-interest organizations.

Marketing Animal-Friendly Products: Addressing the Consumer Social Dilemma with Reinforcement Positioning Strategies

Directory of Open Access Journals (Sweden)

Lenka van Riemsdijk

2017-12-01

Full Text Available This article presents a conceptual framework that aims to encourage consumer animal-friendly product choice by introducing positioning strategies for animal-friendly products. These strategies reinforce the animal welfare with different types of consumption values and can therefore reduce consumers’ social dilemma, which is a major barrier to animal-friendly consumer choices. The article suggests how animal-friendly products can use various types of consumption values (functional, sensory, emotional, social, epistemic and situational to create an attractive position relative to their competitors. It also explains why some consumer segments, such as those with a specific thinking style, may experience a stronger effect of some strategies, giving directions on how to approach different types of consumers. Finally, building on research asserting that animal welfare is a credence product attribute, the article proposes moderating effects of two factors that help consumers to evaluate the credibility of animal welfare claims, namely corporate social responsibility strategy and the role of stakeholders. Here it concludes that companies selling animal-friendly products need to be aware of the impact of their overall strategy on the effectiveness of positioning strategies for individual products and that, to gain consumer trust, they may need to collaborate with relevant stakeholders, such as media or animal-interest organizations.

Tough ceramic coatings: Carbon nanotube reinforced silica sol-gel

Science.gov (United States)

López, A. J.; Rico, A.; Rodríguez, J.; Rams, J.

2010-08-01

Silica coatings reinforced with carbon nanotubes were produced via sol-gel route using two mixing techniques of the sol-gel precursors, mechanical and ultrasonic mixing, and dip-coating as deposition process on magnesium alloy substrates. Effective incorporation and distribution of 0.1 wt.% of carbon nanotubes in the amorphous silica matrix of the coatings were achieved using both techniques. Fabrication procedure determines the morphological aspects of the coating. Only mechanical mixing process produced coatings dense and free of defects. Nanoindentation technique was used to examine the influence of the fabrication process in the mechanical features of the final coatings, i.e. indentation fracture toughness, Young's modulus and hardness. A maximum toughening effect of about 24% was achieved in silica coatings reinforced with carbon nanotubes produced by the mechanical mixing route. Scanning electron microscopy investigation revealed that the toughening of these reinforced coatings was mainly due to bridging effect of the reinforcement.

[Impact on the gait time cycle of ischemic stroke in the treatment with yin-yang respiratory reinforcing and reducing needling technique].

Science.gov (United States)

Li, Qi; Tian, Fu-Ling; Liu, Guo-Rong; Zheng, De-Song; Chen, Jin-Ming; Ma, Shu-Riang; Cui, Jian-Mei; Wang, Hong-Bin; Li, Xue-Qing

2014-03-01

To compare the difference in the efficacy on gait time cycle of ischemic stroke between yin-yang respiratory reinforcing and reducing needling technique (yin-yang needling) and the conventional acupuncture. Sixty cases of ischemic stroke were randomized into a conventional acupuncture group and a yin-yang needling group, 30 cases in each one. The basic treatment (the control of blood pressure, blood sugar and blood lipid, the intravenous drops of ginkgo leaf extract and dipyridamole injection and vinpocetine injection) were applied in the two groups. Additionally, in the conventional acupuncture group, the acupoints of the Stomach Meridian of Foot-Yangming [Biguan (ST 31), Liangqiu (ST 34), Zusanli (ST 36), Shangjuxu (ST 37), Xiajuxu (ST 39), etc.] were selected and stimulated with the even needling technique. In the yin-yang needling group, the acupoints of yin meridians such as Zuwuli (LR 10), Xuehai (SP 10), Yinlingquan (SP 9) and Sanyinjiao (SP 6), etc. and the acupoints of yang meridians such as Biguan (ST 31), Liangqiu (ST 34) and Yanglingquan (GB 34), etc. were selected. The reducing manipulation of respiratory reinforcing and reducing technique was applied to the acupoints of yin meridians and the reinforcing manipulation was applied to the acupoints of yang meridians. The kinematics time parameters were determined and compared before and 4 weeks after treatment. After treatment, the differences in the gait cycle, the phase time of standing (%), the phase time of single support (%), the phase time of unilateral sway (%) on the affected (healthy) foot and phase time of double support (%) were significant as compared with those before treatment in the patients of the two groups (all P yin-yang needling group were improved much obviously after treatment as compared with those in the conventional acupuncture group. The differences in support phase time (%), single support phase time (%) and sway phase time (%) were significant between the affected limb and

Open table-top device positioning technique to reduce small bowel obstruction. Positioning accuracy and impact on conformal radiation therapy techniques

International Nuclear Information System (INIS)

Rudat, V.; Flentje, M.; Engenhart, R.; Metzger, M.; Wannenmacher, M.

1995-01-01

The immobilization error of patients positioned on the opern table-top device in prone prosition as well as the movement of the small bowel out of the pelvis by this positioning technique was determined. The positioning error is of special importance for the 3-dimensional treatment planning for conformal radiotherapy. The positioning error was determined by superposing 106 portal films with the corresponding simultor films from 21 patients with carcinoma of the rectum who received 3D-planned conformal radiotherapy (o-field technique with irregular blocks). The movement of the small bowel out of the pelvis was studied by comparing simulator films after barium swallow in supine and open table-top position as well with 3D-treatment plans of the same patient in both positions in 3 cases. The positioning error along the medio-lateral, dorso-ventral und cranio-caudal axis was 1.4/-0.6/1.8 mm and the standard deviation 4.4/6.8/6.3 mm, respectively. In comparison to the supine position more rotation errors in the sagittal view were observed (37% and 9% respectively) with a media of 5.1 . Six out of 22 patients showed no adhesions of the small bowel and a complete movement out of the tratment field was achieved. 14 out of 16 Patients with adhesions revealed a partial movement of the small bowel out of the treatment field. Comparing 3D-treatment plans in both positions again demonstrated a marked reduction of the irradiated small bowel volume with the use of the open table-top decive. (orig.) [de

An Analysis of Stochastic Game Theory for Multiagent Reinforcement Learning

National Research Council Canada - National Science Library

Bowling, Michael

2000-01-01

.... In this paper we contribute a comprehensive presentation of the relevant techniques for solving stochastic games from both the game theory community and reinforcement learning communities. We examine the assumptions and limitations of these algorithms, and identify similarities between these algorithms, single agent reinforcement learners, and basic game theory techniques.

Internal inspection of reinforced concrete for nuclear structures using shear wave tomography

International Nuclear Information System (INIS)

Scott, David B.

2013-01-01

Highlights: • Aging of reinforced concrete used for worldwide nuclear structures is increasing and necessitating evaluation. • Nondestructive evaluation is a tool for assessing the condition of reinforced concrete of nuclear structures. • Ultrasonic shear wave tomography as a stress wave technique has begun to be utilized for investigation of concrete material. • A study using ultrasonic shear wave tomography indicates anomalies vital to the long-term operation of the structure. • The use of this technique has shown to successfully evaluate the internal state of reinforced concrete members. - Abstract: Reinforced concrete is important for nuclear related structures. Therefore, the integrity of structural members consisting of reinforced concrete is germane to the safe operation and longevity of these facilities. Many issues that reduce the likelihood of safe operation and longevity are not visible on the surface of reinforced concrete material. Therefore, an investigation of reinforced concrete material should include techniques which will allow peering into the concrete member and determining its internal state. The performance of nondestructive evaluations is pursuant to this goal. Some of the categories of nondestructive evaluations are electrochemical, magnetism, ground penetrating radar, and ultrasonic testing. A specific ultrasonic testing technique, namely ultrasonic shear wave tomography, is used to determine presence and extent of voids, honeycombs, cracks perpendicular to the surface, and/or delamination. This technique, and others similar to it, has been utilized in the nuclear industry to determine structural conditions

Arthroscopic Latarjet Techniques: Graft and Fixation Positioning Assessed With 2-Dimensional Computed Tomography Is Not Equivalent With Standard Open Technique.

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Neyton, Lionel; Barth, Johannes; Nourissat, Geoffroy; Métais, Pierre; Boileau, Pascal; Walch, Gilles; Lafosse, Laurent

2018-05-19

To analyze graft and fixation (screw and EndoButton) positioning after the arthroscopic Latarjet technique with 2-dimensional computed tomography (CT) and to compare it with the open technique. We performed a retrospective multicenter study (March 2013 to June 2014). The inclusion criteria included patients with recurrent anterior instability treated with the Latarjet procedure. The exclusion criterion was the absence of a postoperative CT scan. The positions of the hardware, the positions of the grafts in the axial and sagittal planes, and the dispersion of values (variability) were compared. The study included 208 patients (79 treated with open technique, 87 treated with arthroscopic Latarjet technique with screw fixation [arthro-screw], and 42 treated with arthroscopic Latarjet technique with EndoButton fixation [arthro-EndoButton]). The angulation of the screws was different in the open group versus the arthro-screw group (superior, 10.3° ± 0.7° vs 16.9° ± 1.0° [P open inferior screws (P = .003). In the axial plane (level of equator), the arthroscopic techniques resulted in lateral positions (arthro-screw, 1.5 ± 0.3 mm lateral [P open technique (0.9 ± 0.2 mm medial). At the level of 25% of the glenoid height, the arthroscopic techniques resulted in lateral positions (arthro-screw, 0.3 ± 0.3 mm lateral [P open technique (1.0 ± 0.2 mm medial). Higher variability was observed in the arthro-screw group. In the sagittal plane, the arthro-screw technique resulted in higher positions (55% ± 3% of graft below equator) and the arthro-EndoButton technique resulted in lower positions (82% ± 3%, P open technique (71% ± 2%). Variability was not different. This study shows that the position of the fixation devices and position of the bone graft with the arthroscopic techniques are statistically significantly different from those with the open technique with 2-dimensional CT assessment. In the sagittal plane, the arthro-screw technique provides the highest

Neurofeedback in Learning Disabled Children: Visual versus Auditory Reinforcement.

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Fernández, Thalía; Bosch-Bayard, Jorge; Harmony, Thalía; Caballero, María I; Díaz-Comas, Lourdes; Galán, Lídice; Ricardo-Garcell, Josefina; Aubert, Eduardo; Otero-Ojeda, Gloria

2016-03-01

Children with learning disabilities (LD) frequently have an EEG characterized by an excess of theta and a deficit of alpha activities. NFB using an auditory stimulus as reinforcer has proven to be a useful tool to treat LD children by positively reinforcing decreases of the theta/alpha ratio. The aim of the present study was to optimize the NFB procedure by comparing the efficacy of visual (with eyes open) versus auditory (with eyes closed) reinforcers. Twenty LD children with an abnormally high theta/alpha ratio were randomly assigned to the Auditory or the Visual group, where a 500 Hz tone or a visual stimulus (a white square), respectively, was used as a positive reinforcer when the value of the theta/alpha ratio was reduced. Both groups had signs consistent with EEG maturation, but only the Auditory Group showed behavioral/cognitive improvements. In conclusion, the auditory reinforcer was more efficacious in reducing the theta/alpha ratio, and it improved the cognitive abilities more than the visual reinforcer.

Seismic Retrofitting: Reinforced Concrete (RC shear wall versus Reinforcement of RC element by Carbon Fiber Reinforced Polymer (CFRP using PUSHOVER analysis

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Yahya RIYAD

2016-12-01

Full Text Available Seismic retrofitting of constructions vulnerable to earthquakes is a current problem of great political and social relevance. During the last sixty years, moderate to severe earthquakes have occurred in Morocco (specifically in Agadir 1960 and Hoceima 2004. Such events have clearly shown the vulnerability of the building stock in particular and of the built environment in general. Hence, it is very much essential to retrofit the vulnerable building to cope up for the next damaging earthquake. In this paper, the focus will be on a comparative study between two techniques of seismic retrofitting, the first one is a reinforcement using carbon fiber reinforced polymer (CFRP applied to RC elements by bonding , and the second one is a reinforcement with a shear wall. For this study, we will use a non-linear static analysis -also known as Pushover analysis - on a reinforced concrete structure consisting of beams and columns, and composed from eight storey with a gross area of 240 m², designed conforming to the Moroccan Seismic code[1].

Man-made vitreous fiber produced from incinerator ash using the thermal plasma technique and application as reinforcement in concrete.

Science.gov (United States)

Yang, Sheng-Fu; Wang, To-Mai; Lee, Wen-Cheng; Sun, Kin-Seng; Tzeng, Chin-Ching

2010-10-15

This study proposes using thermal plasma technology to treat municipal solid waste incinerator ashes. A feasible fiberization method was developed and applied to produce man-made vitreous fiber (MMVF) from plasma vitrified slag. MMVF were obtained through directly blending the oxide melt stream with high velocity compressed air. The basic technological characteristics of MMVF, including morphology, diameter, shot content, length and chemical resistance, are described in this work. Laboratory experiments were conducted on the fiber-reinforced concrete. The effects of fibrous content on compressive strength and flexural strength are presented. The experimental results showed the proper additive of MMVF in concrete can enhance its mechanical properties. MMVF products produced from incinerator ashes treated with the thermal plasma technique have great potential for reinforcement in concrete. 2010 Elsevier B.V. All rights reserved.

Reinforced soil structures. Volume I, Design and construction guidelines

Science.gov (United States)

1990-11-01

This report presents comprehensive guidelines for evaluating and using soil reinforcement techniques in the construction of retaining walls, embankment slopes, and natural or cut slopes. A variety of available systems for reinforced soil including in...

Sex Differences in Reinforcement and Punishment on Prime-Time Television.

Science.gov (United States)

Downs, A. Chris; Gowan, Darryl C.

1980-01-01

Television programs were analyzed for frequencies of positive reinforcement and punishment exchanged among performers varying in age and sex. Females were found to more often exhibit and receive reinforcement, whereas males more often exhibited and received punishment. These findings have implications for children's learning of positive and…

Positive reinforcement to promote safer sex among clients.

Science.gov (United States)

Raman, S

1992-01-01

The AIDS Research Foundation of India (ARFI) began an intervention program with sex workers in Madras where the women reported that they were willing to use condoms, whereas the customers were not. Accordingly, ARFI is focusing on clients using a positive reinforcement approach: repetition of the desirability of condom use by communication. First, truck drivers and dock workers have been targeted. Drivers interviewed by ARFI were familiar with the condom as a contraceptive method rather than a disease-preventing method, and used it with their wives. The ARFI program has convinced tobacco shopkeepers to stock condoms for drivers. Truckers receive key chains with a holder for a condom. At transit site tea shops songs are aired about road and roadside safety sponsored by a tire manufacturer with a message about rubber (tires and condoms). Women selling sex at transit sites are also educated about the human immunodeficiency virus (HIV) infection and sexually transmitted diseases (STDs) while attempting to increase their level of hygiene. The typical Friday night sex-seeking behavior among dock workers consists of drinking in a wine shop and soliciting sex workers. Port management and unions have also been recruited for promoting AIDS-related education after participating in health education sessions with flip charts and flash cards. Rest rooms display posters on condom use, some men have been recruited as condom holders for distribution on Friday nights, and barber shops also feature posters with messages about safer sex. AIDS/STD prevention programs have to deal with prevailing practices, values, and beliefs. Results indicate increased condom use among clients as shown by increased sales at transit site tobacco shops and shops around the port. In the future the program will pay more attention to improving the negotiation skills of sex workers.

Toughened microstructures for ductile phase reinforced molybdenum disilicide

International Nuclear Information System (INIS)

Pickard, S.M.; Ghosh, A.K.

1995-01-01

Various morphologies of ductile Nb refractory metal reinforcement are incorporated into a MoSi 2 matrix using powder metallurgy, including single-ply laminates, continuous metal ribbons and sections of 2-dimensional wire mesh. Hot forging techniques are used to redistribute the reinforcement and change the dimensions and the aspect ratio of the reinforcing metal ligaments. Work-of-rupture measurements are conducted on bend test specimens and precracked tensile specimens of the composite so that the toughness contribution from the various ductile metal morphologies can be assessed according to its effectiveness. Accompanying microstructural examination of crack bridging interaction with the reinforcement is conducted

Acoustic emission techniques applied to conventionally reinforced concrete bridge girders.

Science.gov (United States)

2008-09-01

Reinforced concrete (RC) bridges generally operate at service-level loads except during discrete overload events that can reduce the integrity of the structure by initiating concrete cracks, widening or extending of existing concrete cracks, as well ...

Employment-based abstinence reinforcement following inpatient detoxification in HIV-positive opioid and/or cocaine-dependent patients.

Science.gov (United States)

Dunn, Kelly E; Fingerhood, Michael; Wong, Conrad J; Svikis, Dace S; Nuzzo, Paul; Silverman, Kenneth

2014-02-01

Employment-based reinforcement interventions have been used to promote abstinence from drugs among chronically unemployed injection drug users. The current study used an employment-based reinforcement intervention to promote opioid and cocaine abstinence among opioid and/or cocaine-dependent, HIV-positive participants who had recently completed a brief inpatient detoxification. Participants (n = 46) were randomly assigned to an abstinence and work group that was required to provide negative urine samples in order to enter the workplace and to earn incentives for work (n = 16), a work-only group that was permitted to enter the workplace and to earn incentives independent of drug use (n = 15), and a no-voucher control group that did not receive any incentives for working (n = 15) over a 26-week period. The primary outcome was urinalysis-confirmed opioid, cocaine, and combined opioid/cocaine abstinence. Participants were 78% male and 89% African American. Results showed no significant between-groups differences in urinalysis-verified drug abstinence or HIV risk behaviors during the 6-month intervention. The work-only group had significantly greater workplace attendance, and worked more minutes per day when compared to the no-voucher group. Several features of the study design, including the lack of an induction period, setting the threshold for entering the workplace too high by requiring immediate abstinence from several drugs, and increasing the risk of relapse by providing a brief detoxification that was not supported by any continued pharmacological intervention, likely prevented the workplace from becoming established as a reinforcer that could be used to promote drug abstinence. However, increases in workplace attendance have important implications for adult training programs.

Reinforced Ultra-Tightly Coupled GPS/INS System for Challenging Environment

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Xueyun Wang

2014-01-01

Full Text Available Among all integration levels currently available for Global Positioning System (GPS and Inertial Navigation System (INS Integrated System, ultra-tightly coupled (UTC GPS/INS system is the best choice for accurate and reliable navigation. Nevertheless the performance of UTC GPS/INS system degrades in challenging environments, such as jamming, changing noise of GPS signals, and high dynamic maneuvers. When low-end Inertial Measurement Units (IMUs based on MEMS sensors are employed, the performance degradation will be more severe. To solve this problem, a reinforced UTC GPS/INS system is proposed. Two techniques are adopted to deal with jamming and high dynamics. Firstly, adaptive integration Kalman filter (IKF based on fuzzy logics is developed to reinforce the antijamming ability. The parameters of membership functions (MFs are adjusted and optimized through self-developed neutral network. Secondly, a Doppler frequency error estimator based on Kalman filter is designed to improve the navigation performance under high dynamics. A complete simulation platform is established to evaluate the reinforced system. Results demonstrate that the proposed system architecture significantly improves navigation performance in challenging environments and it is a more advanced solution to accurate and reliable navigation than traditional UTC GPS/INS system.

Facilitating tolerance of delayed reinforcement during functional communication training.

Science.gov (United States)

Fisher, W W; Thompson, R H; Hagopian, L P; Bowman, L G; Krug, A

2000-01-01

Few clinical investigations have addressed the problem of delayed reinforcement. In this investigation, three individuals whose destructive behavior was maintained by positive reinforcement were treated using functional communication training (FCT) with extinction (EXT). Next, procedures used in the basic literature on delayed reinforcement and self-control (reinforcer delay fading, punishment of impulsive responding, and provision of an alternative activity during reinforcer delay) were used to teach participants to tolerate delayed reinforcement. With the first case, reinforcer delay fading alone was effective at maintaining low rates of destructive behavior while introducing delayed reinforcement. In the second case, the addition of a punishment component reduced destructive behavior to near-zero levels and facilitated reinforcer delay fading. With the third case, reinforcer delay fading was associated with increases in masturbation and head rolling, but prompting and praising the individual for completing work during the delay interval reduced all problem behaviors and facilitated reinforcer delay fading.

Increasing the bit rate in OCDMA systems using pulse position modulation techniques.

Science.gov (United States)

Arbab, Vahid R; Saghari, Poorya; Haghi, Mahta; Ebrahimi, Paniz; Willner, Alan E

2007-09-17

We have experimentally demonstrated two novel pulse position modulation techniques, namely Double Pulse Position Modulation (2-PPM) and Differential Pulse Position Modulation (DPPM) in Time-Wavelength OCDMA systems that will operate at a higher bit rate compared to traditional OOK-OCDMA systems with the same bandwidth. With 2-PPM technique, the number of active users will be more than DPPM while their bit rate is almost the same. Both techniques provide variable quality of service in OCDMA networks.

Investigation on reinforced concrete slabs subjeted to impact loading

International Nuclear Information System (INIS)

Freiman, M.; Krutzik, N.J.; Tropp, R.; Zorn, N.F.

1984-01-01

A comparison of experimental and computational results for tests of reinforced concrete slabs subjected to soft missile impact is presented. Numerical simulation techniques were employed to predict the target response. The objective of the calculations was to validate the material model for reinforced concrete implemented in a finite difference code. The computational results regarding displacements or strains in the reinforcement conform satisfactorily with the experimental values. (Author) [pt

Reinforcement learning techniques for controlling resources in power networks

Science.gov (United States)

Kowli, Anupama Sunil

As power grids transition towards increased reliance on renewable generation, energy storage and demand response resources, an effective control architecture is required to harness the full functionalities of these resources. There is a critical need for control techniques that recognize the unique characteristics of the different resources and exploit the flexibility afforded by them to provide ancillary services to the grid. The work presented in this dissertation addresses these needs. Specifically, new algorithms are proposed, which allow control synthesis in settings wherein the precise distribution of the uncertainty and its temporal statistics are not known. These algorithms are based on recent developments in Markov decision theory, approximate dynamic programming and reinforcement learning. They impose minimal assumptions on the system model and allow the control to be "learned" based on the actual dynamics of the system. Furthermore, they can accommodate complex constraints such as capacity and ramping limits on generation resources, state-of-charge constraints on storage resources, comfort-related limitations on demand response resources and power flow limits on transmission lines. Numerical studies demonstrating applications of these algorithms to practical control problems in power systems are discussed. Results demonstrate how the proposed control algorithms can be used to improve the performance and reduce the computational complexity of the economic dispatch mechanism in a power network. We argue that the proposed algorithms are eminently suitable to develop operational decision-making tools for large power grids with many resources and many sources of uncertainty.

Corrosion Measurements in Reinforced Fly Ash Concrete Containing Steel Fibres Using Strain Gauge Technique

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V. M. Sounthararajan

2013-01-01

Full Text Available Corrosion of steel bars in concrete is a serious problem leading to phenomenal volume expansion and thereby leading to cover concrete spalling. It is well known that the reinforced concrete structures subjected to chloride attack during its service life cause these detrimental effects. The early detection of this damage potential can extend the service life of concrete. This study reports the comprehensive experimental studies conducted on the identification of corrosion mechanism in different types of reinforced concrete containing class-F fly ash and hooked steel fibres. Fly ash replaced concrete mixes were prepared with 25% and 50% fly ash containing steel fibres at 0.5%, 1.0%, and 1.5% by volume fraction. Corrosion process was investigated in an embedded steel bar (8 mm diameter reinforced in concrete by passing an impressed current in sodium chloride solution. Strain gauge attached to the rebars was monitored for electrical measurements using strain conditioner. Strain gauge readings observed during the corrosion process exhibited the volume changes of the reinforcement embedded inside the concrete. The corrosion potential of different steel fibre reinforced concrete mixes with fly ash addition showed higher resistance towards the corrosion initiation.

Adolescent-specific patterns of behavior and neural activity during social reinforcement learning.

Science.gov (United States)

Jones, Rebecca M; Somerville, Leah H; Li, Jian; Ruberry, Erika J; Powers, Alisa; Mehta, Natasha; Dyke, Jonathan; Casey, B J

2014-06-01

Humans are sophisticated social beings. Social cues from others are exceptionally salient, particularly during adolescence. Understanding how adolescents interpret and learn from variable social signals can provide insight into the observed shift in social sensitivity during this period. The present study tested 120 participants between the ages of 8 and 25 years on a social reinforcement learning task where the probability of receiving positive social feedback was parametrically manipulated. Seventy-eight of these participants completed the task during fMRI scanning. Modeling trial-by-trial learning, children and adults showed higher positive learning rates than did adolescents, suggesting that adolescents demonstrated less differentiation in their reaction times for peers who provided more positive feedback. Forming expectations about receiving positive social reinforcement correlated with neural activity within the medial prefrontal cortex and ventral striatum across age. Adolescents, unlike children and adults, showed greater insular activity during positive prediction error learning and increased activity in the supplementary motor cortex and the putamen when receiving positive social feedback regardless of the expected outcome, suggesting that peer approval may motivate adolescents toward action. While different amounts of positive social reinforcement enhanced learning in children and adults, all positive social reinforcement equally motivated adolescents. Together, these findings indicate that sensitivity to peer approval during adolescence goes beyond simple reinforcement theory accounts and suggest possible explanations for how peers may motivate adolescent behavior.

Thermally sprayed prepregs for thixoforging of UD fiber reinforced light metal MMCs

Science.gov (United States)

Silber, Martin; Wenzelburger, Martin; Gadow, Rainer

2007-04-01

Low density and good mechanical properties are the basic requirements for lightweight structures in automotive and aerospace applications. With their high specific strength and strain to failure values, aluminum alloys could be used for such applications. Only the insufficient stiffness and thermal and fatigue strength prevented their usage in high-end applications. One possibility to solve this problem is to reinforce the light metal with unidirectional fibers. The UD fiber allows tailoring of the reinforcement to meet the direction of the component's load. In this study, the production of thermally sprayed prepregs for the manufacturing of continuous fiber reinforced MMC by thixoforging is analysed. The main aim is to optimize the winding procedure, which determines the fiber strand position and tension during the coating process. A method to wind and to coat the continuous fibers with an easy-to-use handling technique for the whole manufacturing process is presented. The prepregs were manufactured by producing arc wire sprayed AlSi6 coatings on fibers bundles. First results of bending experiments showed appropriate mechanical properties.

Soil reinforcement with geosynthetics

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Bessaim Mohammed Mustapha

2018-01-01

Full Text Available The proportionality of existence of land with good bearing to erect any building or building is very small, to remedy this deficiency it is necessary to resort to techniques of reinforcement of the soils which can constitute a very important development. Among these methods of remediation, there is reinforcement by the geosynthetics which constitute an effective solution to these constraints. This process tends to stabilize the soil in question with increased load bearing capacity in civil engineering and geotechnical works such as embankments, slopes, embankments and hydraulic structures, with an inestimable gain in time, economy and durability while preserving the natural and environmental aspect.

Application of a Reinforced Self-Compacting Concrete Jacket in Damaged Reinforced Concrete Beams under Monotonic and Repeated Loading

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Constantin E. Chalioris

2013-01-01

Full Text Available This paper presents the findings of an experimental study on the application of a reinforced self-compacting concrete jacketing technique in damaged reinforced concrete beams. Test results of 12 specimens subjected to monotonic loading up to failure or under repeated loading steps prior to total failure are included. First, 6 beams were designed to be shear dominated, constructed by commonly used concrete, were initially tested, damaged, and failed in a brittle manner. Afterwards, the shear-damaged beams were retrofitted using a self-compacting concrete U-formed jacket that consisted of small diameter steel bars and U-formed stirrups in order to increase their shear resistance and potentially to alter their initially observed shear response to a more ductile one. The jacketed beams were retested under the same loading. Test results indicated that the application of reinforced self-compacting concrete jacketing in damaged reinforced concrete beams is a promising rehabilitation technique. All the jacketed beams showed enhanced overall structural response and 35% to 50% increased load bearing capacities. The ultimate shear load of the jacketed beams varied from 39.7 to 42.0 kN, whereas the capacity of the original beams was approximately 30% lower. Further, all the retrofitted specimens exhibited typical flexural response with high values of deflection ductility.

Behavior of reinforced concrete beams reinforced with GFRP bars

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D. H. Tavares

Full Text Available The use of fiber reinforced polymer (FRP bars is one of the alternatives presented in recent studies to prevent the drawbacks related to the steel reinforcement in specific reinforced concrete members. In this work, six reinforced concrete beams were submitted to four point bending tests. One beam was reinforced with CA-50 steel bars and five with glass fiber reinforced polymer (GFRP bars. The tests were carried out in the Department of Structural Engineering in São Carlos Engineering School, São Paulo University. The objective of the test program was to compare strength, reinforcement deformation, displacement, and some anchorage aspects between the GFRP-reinforced concrete beams and the steel-reinforced concrete beam. The results show that, even though four GFRP-reinforced concrete beams were designed with the same internal tension force as that with steel reinforcement, their capacity was lower than that of the steel-reinforced beam. The results also show that similar flexural capacity can be achieved for the steel- and for the GFRP-reinforced concrete beams by controlling the stiffness (reinforcement modulus of elasticity multiplied by the bar cross-sectional area - EA and the tension force of the GFRP bars.

Automatic design of the flexural strengthening of reinforced concrete beams using fiber reinforced polymers (FRP - doi: 10.4025/actascitechnol.v34i2.8318

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Rafael Alves de Souza

2012-03-01

Full Text Available Changing the functions of a building, the presence of some design or construction errors, the incidence of seismic actions and even the updating of design codes may demand the strengthening of certain structures. In the specific case of reinforced concrete structures it is desirable the application of a technique of strengthening which is fast, economic and efficient, in order to provide advantages when an intervention is necessary. The technique of strengthening chosen must provide less disorder as possible as well as the guaranty of safety. Taking into account this scenery, fiber reinforced polymers have been working as a very attractive alternative for rehabilitating in-service structures. In that way, the present study aims at presenting the main properties of this new material as well as the design routines for flexural strengthening of reinforced concrete beams. Finally, a package-software developed into the MATLAB platform is presented, intending to generate a simple tool for the automatic design using fiber reinforced polymers.

Equivalence relations and the reinforcement contingency.

Science.gov (United States)

Sidman, M

2000-07-01

Where do equivalence relations come from? One possible answer is that they arise directly from the reinforcement contingency. That is to say, a reinforcement contingency produces two types of outcome: (a) 2-, 3-, 4-, 5-, or n-term units of analysis that are known, respectively, as operant reinforcement, simple discrimination, conditional discrimination, second-order conditional discrimination, and so on; and (b) equivalence relations that consist of ordered pairs of all positive elements that participate in the contingency. This conception of the origin of equivalence relations leads to a number of new and verifiable ways of conceptualizing equivalence relations and, more generally, the stimulus control of operant behavior. The theory is also capable of experimental disproof.

The influence of the weld toe grinding and wig remelting weld toe rehabilitation techniques, on variable stresses, in case of cross fillet welds, reinforced with additional welding rows

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Babis Claudiu

2017-01-01

Full Text Available Variable stresses where the load value varies between a maximum and a minimum value, or varies the position in time, cause after accumulating a large number of load cycles in those structures, the emergence of drug fatigue. Fatigue is characterized by failure on values of the applied stress from the load cycles, below the material flow, values which in case of static stress would not have caused problems. Knowing that the variable stressed structures are sensitive to stress concentrators, the paper aims to highlight the influence of two techniques to reduce stress concentrator weld toe grinding and WIG remelting weld toe, on the behavior of variable tensile test of cross corner welded specimens, reinforced with additional welding rows.

Technique for reinforcing development working in lower strata of thick coal seams

Energy Technology Data Exchange (ETDEWEB)

Andranovich, V A; Gromov, Yu V; Kurglikov, V P

1981-01-15

This device is to be used by mining industry, specifically for reinforcing development work in bottom strata of thick coal seams having a layer depression. Reinforcing consists of drilling a hole, or making cutting slits and lowering support props for the stratum below through them, as well as lowering the roof timber on the ground. To cut back expenditures on installation and removal of equipment, drilling or making cutting slits is done to a depth equal to the total height of the substrata, and the support props are laid for all of the substrata. Only the roof timber is lowered on the ground during work on the layers.

Origins of food reinforcement in infants12345

Science.gov (United States)

Kong, Kai Ling; Feda, Denise M; Eiden, Rina D; Epstein, Leonard H

2015-01-01

Background: Rapid weight gain in infancy is associated with a higher risk of obesity in children and adults. A high relative reinforcing value of food is cross-sectionally related to obesity; lean children find nonfood alternatives more reinforcing than do overweight/obese children. However, to our knowledge, there is no research on how and when food reinforcement develops. Objective: This study was designed to assess whether the reinforcing value of food and nonfood alternatives could be tested in 9- to 18-mo-old infants and whether the reinforcing value of food and nonfood alternatives is differentially related to infant weight status. Design: Reinforcing values were assessed by using absolute progressive ratio schedules of reinforcement, with presentation of food and nonfood alternatives counterbalanced in 2 separate studies. Two nonfood reinforcers [Baby Einstein–Baby MacDonald shows (study 1, n = 27) or bubbles (study 2, n = 30)] were tested against the baby’s favorite food. Food reinforcing ratio (FRR) was quantified by measuring the reinforcing value of food (Food Pmax) in proportion to the total reinforcing value of food and a nonfood alternative (DVD Pmax or BUB Pmax). Results: Greater weight-for-length z score was associated with a greater FRR of a favorite food in study 1 (FRR-DVD) (r = 0.60, P positively associated with FRR-DVD (r = 0.57, P = 0.009) and FRR-BUB (r = 0.37, P = 0.047). Conclusions: Our newly developed paradigm, which tested 2 different nonfood alternatives, demonstrated that lean infants find nonfood alternatives more reinforcing than do overweight/obese infants. This observation suggests that strengthening the alternative reinforcers may have a protective effect against childhood obesity. This research was registered at clinicaltrials.gov as NCT02229552. PMID:25733636

Soft soils reinforced by rigid vertical inclusions

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Iulia-Victoria NEAGOE

2013-12-01

Full Text Available Reinforcement of soft soils by rigid vertical inclusions is an increasingly used technique over the last few years. The system consists of rigid or semi-rigid vertical inclusions and a granular platform for the loads transfer from the structure to the inclusions. This technique aims to reduce the differential settlements both at ground level as below the structure. Reinforcement by rigid inclusions is mainly used for foundation works for large commercial and industrial platforms, storage tanks, wastewater treatment plants, wind farms, bridges, roads, railway embankments. The subject is one of interest as it proves the recently concerns at international level in research and design; however, most studies deal more with the static behavior and less with the dynamic one.

Numerical analysis of pipe impact on reinforced concrete structures

International Nuclear Information System (INIS)

Prinja, N.K.

1990-01-01

This paper presents the methodology and the results of numerical analyses carried out by using the computer code DYNA3D to analyse pipe impacts on a reinforced concrete slab, a floor beam and a column. Modelling techniques employed to represent various features of typical reinforced concrete (RC) structures and the details of a soil and crushable foam type of material model used to represent concrete material behaviour are described. The results show that a reasonable prediction of global behaviour of reinforced concrete structures under impact loading can be obtained by this numerical method. (author)

Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

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Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

2014-01-01

Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion. PMID:24558346

Monitoring corrosion of steel bars in reinforced concrete structures.

Science.gov (United States)

Verma, Sanjeev Kumar; Bhadauria, Sudhir Singh; Akhtar, Saleem

2014-01-01

Corrosion of steel bars embedded in reinforced concrete (RC) structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP) method. This paper also presents few techniques to protect concrete from corrosion.

Monitoring Corrosion of Steel Bars in Reinforced Concrete Structures

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Sanjeev Kumar Verma

2014-01-01

Full Text Available Corrosion of steel bars embedded in reinforced concrete (RC structures reduces the service life and durability of structures causing early failure of structure, which costs significantly for inspection and maintenance of deteriorating structures. Hence, monitoring of reinforcement corrosion is of significant importance for preventing premature failure of structures. This paper attempts to present the importance of monitoring reinforcement corrosion and describes the different methods for evaluating the corrosion state of RC structures, especially hal-cell potential (HCP method. This paper also presents few techniques to protect concrete from corrosion.

Surface Heave Behaviour of Coir Geotextile Reinforced Sand Beds

Science.gov (United States)

Lal, Dharmesh; Sankar, N.; Chandrakaran, S.

2017-06-01

Soil reinforcement by natural fibers is one of the cheapest and attractive ground improvement techniques. Coir is the most abundant natural fiber available in India and due to its high lignin content; it has a larger life span than other natural fibers. It is widely used in India for erosion control purposes, but its use as a reinforcement material is rather limited. This study focuses on the use of coir geotextile as a reinforcement material to reduce surface heave phenomena occurring in shallow foundations. This paper presents the results of laboratory model tests carried out on square footings supported on coir geotextile reinforced sand beds. The influence of various parameters such as depth of reinforcement, length, and number of layers of reinforcement was studied. It was observed that surface heave is considerably reduced with the provision of geotextile. Heave reduction up to 98.7% can be obtained by the proposed method. Heave reduction is quantified by a non-dimensional parameter called heave reduction factor.

Recent Positioning Techniques for Efficient Port Operations and Development of Suez Canal Corridor

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Ahmed Elhattab

2016-12-01

Full Text Available The current developments in positioning techniques and communication technology have great impact on both construction and operations of ports. The majority of positioning systems for marine traffic are satellite based such as GPS. Virtual Reference Station is one of the recent high precision techniques for GNSS positioning which can be used for smart and efficient port.The advantages of using virtual reference station technique in different port operation and construction have been discussed in this paper. To apply this technique in Suez Canal corridor zone, a design of Continuously Operating Reference Station network has been proposed. This network can be utilized during different construction and operations phases of Suez Canal Corridor project.  

Braided reinforced composite rods for the internal reinforcement of concrete

Science.gov (United States)

Gonilho Pereira, C.; Fangueiro, R.; Jalali, S.; Araujo, M.; Marques, P.

2008-05-01

This paper reports on the development of braided reinforced composite rods as a substitute for the steel reinforcement in concrete. The research work aims at understanding the mechanical behaviour of core-reinforced braided fabrics and braided reinforced composite rods, namely concerning the influence of the braiding angle, the type of core reinforcement fibre, and preloading and postloading conditions. The core-reinforced braided fabrics were made from polyester fibres for producing braided structures, and E-glass, carbon, HT polyethylene, and sisal fibres were used for the core reinforcement. The braided reinforced composite rods were obtained by impregnating the core-reinforced braided fabric with a vinyl ester resin. The preloading of the core-reinforced braided fabrics and the postloading of the braided reinforced composite rods were performed in three and two stages, respectively. The results of tensile tests carried out on different samples of core-reinforced braided fabrics are presented and discussed. The tensile and bending properties of the braided reinforced composite rods have been evaluated, and the results obtained are presented, discussed, and compared with those of conventional materials, such as steel.

Flexural reinforced concrete member with FRP reinforcement

OpenAIRE

Putzolu, Mariana

2017-01-01

One of the most problematic point in construction is the durability of the concrete especially related to corrosion of the steel reinforcement. Due to this problem the construction sector, introduced the use of Fiber Reinforced Polymer, the main fibers used in construction are Glass, Carbon and Aramid. In this study, the author aim to analyse the flexural behaviour of concrete beams reinforced with FRP. This aim is achieved by the analysis of specimens reinforced with GFRP bars, with theoreti...

An improved model for considering strain rate effects on reinforced concrete elements behavior under dynamic loads

International Nuclear Information System (INIS)

Sim, J.; Soroushian, P.

1989-01-01

An improved model for predicting the reinforced concrete element behavior under dynamic strain rates was developed using the layer modeling technique. The developed strain rate sensitive model for axial/flexural analysis of reinforced concrete elements was used to predict the test results, performed at different loading rates, and the predictions were reasonable. The developed analysis technique was used to study the loading rate sensitivity of reinforced concrete beams and columns with different geometry and material properties. Two design formulas for computing the loading rate dependent axial and flexural strengths of reinforced concrete sections are suggested

Techniques for establishing schedules with wheel running as reinforcement in rats.

Science.gov (United States)

Iversen, I H

1993-07-01

In three experiments, access to wheel running was contingent on lever pressing. In each experiment, the duration of access to running was reduced gradually to 4, 5, or 6 s, and the schedule parameters were expanded gradually. The sessions lasted 2 hr. In Experiment 1, a fixed-ratio 20 schedule controlled a typical break-and-run pattern of lever pressing that was maintained throughout the session for 3 rats. In Experiment 2, a fixed-interval schedule of 6 min maintained lever pressing throughout the session for 3 rats, and for 1 rat, the rate of lever pressing was positively accelerated between reinforcements. In Experiment 3, a variable-ratio schedule of 20 or 35 was in effect and maintained lever pressing at a very stable pace throughout the session for 2 of 3 rats; for 1 rat, lever pressing was maintained at an irregular rate. When the session duration was extended to successive 24-hr periods, with food and water accessible in Experiment 3, lever pressing settled into a periodic pattern occurring at a high rate at approximately the same time each day. In each experiment, the rats that developed the highest local rates of running during wheel access also maintained the most stable and highest rates of lever pressing.

[Reinforcement for overdentures on abutment teeth].

Science.gov (United States)

Osada, Tomoko

2006-04-01

This study investigated the effect of the position of reinforcement wires, differences in artificial teeth, and framework designs on the breaking strength of overdentures. The basal surfaces of composite resin teeth and acrylic resin teeth were removed using a carbide bur. A reinforcement wire or a wrought palatal bar was embedded near the occlusal surface or basal surface. Four types of framework structures were designed : conventional skeleton (skeleton), housing with skeleton (housing), housing plus short metal backing (metal backing), and housing plus long metal backing (double structure). After the wires, bars, and frameworks were sand-blasted with 50 microm Al(2)O(3) powder, they were primed with a metal primer and embedded in a heat-polymerized denture base resin. The breaking strengths (N) and maximum stiffness (N/mm) of two-week aged (37 degrees C) specimens were measured using a bending test (n=8). All data obtained at a crosshead speed of 2.0 mm/min were analyzed by ANOVA/Tukey's test (alpha=0.01). There were no statistical differences between the two kinds of artificial teeth (p>0.01). The wrought palatal bar had significantly higher strength than the reinforcement wire (p0.01). The breaking strength and maximum stiffness of the double structure framework were significantly greater (poverdentures were influenced by the size and position of the reinforcement wires. Double structure frameworks are recommended for overdentures to promote a long-term prognosis without denture breakage.

Reinforcement principles for addiction medicine; from recreational drug use to psychiatric disorder.

Science.gov (United States)

Edwards, Scott

2016-01-01

The transition from recreational drug use to addiction can be conceptualized as a pathological timeline whereby the psychological mechanisms responsible for disordered drug use evolve from positive reinforcement to favor elements of negative reinforcement. Abused substances (ranging from alcohol to psychostimulants) are initially ingested at regular occasions according to their positive reinforcing properties. Importantly, repeated exposure to rewarding substances sets off a chain of secondary reinforcing events, whereby cues and contexts associated with drug use may themselves become reinforcing and thereby contribute to the continued use and possible abuse of the substance(s) of choice. Indeed, the powerful reinforcing efficacy of certain drugs may eclipse that of competing social rewards (such as career and family) and lead to an aberrant narrowing of behavioral repertoire. In certain vulnerable individuals, escalation of drug use over time is thought to drive specific molecular neuroadaptations that foster the development of addiction. Research has identified neurobiological elements of altered reinforcement following excessive drug use that comprise within-circuit and between-circuit neuroadaptations, both of which contribute to addiction. Central to this process is the eventual potentiation of negative reinforcement mechanisms that may represent the final definitive criterion locking vulnerable individuals into a persistent state of addiction. Targeting the neural substrates of reinforcement likely represents our best chances for therapeutic intervention for this devastating disease. © 2016 Elsevier B.V. All rights reserved.

Non-destructive elecrochemical monitoring of reinforcement corrosion

DEFF Research Database (Denmark)

Nygaard, Peter Vagn

been widely accepted as a non-destructive ”state of the art” technique for detection of corrosion in concrete structures. And, over the last decade, the trend in corrosion monitoring has moved towards quantitative non-destructive monitoring of the corrosion rate of the steel reinforcement. A few...... corrosion rate measurement instruments have been developed and are commercially available. The main features of these instruments are the combined use of an electrochemical technique for determining the corrosion rate and a so-called ”confinement technique”, which in principle controls the polarised surface...... area of the reinforcement, i.e. the measurement area. Both on-site investigations and laboratory studies have shown that varying corrosion rates are obtained when the various commercially available instruments are used. And in the published studies, conflicting explanations are given illustrating...

Calcium Stabilized And Geogrid Reinforced Soil Structures In Seismic Areas

International Nuclear Information System (INIS)

Rimoldi, Pietro; Intra, Edoardo

2008-01-01

In many areas of Italy, and particularly in high seismic areas, there is no or very little availability of granular soils: hence embankments and retaining structures are often built using the locally available fine soil. For improving the geotechnical characteristics of such soils and/or for building steep faced structures, there are three possible techniques: calcium stabilization, geogrid reinforcement, and the combination of both ones, that is calcium stabilized and reinforced soil. The present paper aims to evaluate these three techniques in terms of performance, design and construction, by carrying out FEM modeling and stability analyses of the same reference embankments, made up of soil improved with each one of the three techniques, both in static and dynamic conditions. Finally two case histories are illustrated, showing the practical application of the above outlined techniques

Modification of glass fibers to improve reinforcement: a plasma polymerization technique

Czech Academy of Sciences Publication Activity Database

Çökeliler, D.; Erkut, S.; Zemek, Josef; Biederman, H.; Mutlu, M.

2007-01-01

Roč. 23, č. 3 (2007), s. 335-342 ISSN 0109-5641 Institutional research plan: CEZ:AV0Z10100521 Keywords : plasma polymerization * glos-discharge * E-glass fibros * ethylendiamine * 2-hydroxyethyl methacrystalate * triethyleneglycoldimethylether * fibre-reinforced composite ( FRC) Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.990, year: 2007

The technique of craniospinal irradiation of paediatric patients in supine position

International Nuclear Information System (INIS)

Slampa, P.; Seneklova, Z.; Simicek, J.; Soumarova, R.; Burkon, P.; Burianova, L.

2001-01-01

Background. Postoperative radiation therapy has significant impact on local control and overall survival of paediatric patients with brain tumours but an irradiated volume is often a controversial issue. Our aim was to describe a new technique of craniospinal irradiation as a postoperative treatment in patients with the risk of relapse of brain tumours as well as to estimate the side effects of such craniospinal irradiation. Patients and methods. In the last 4 years, 17 paediatric patients under 15 years of age with medulloblastoma (8) ependymoma (6) and glioblastoma (3) received postoperative craniospinal axis radiotherapy by a new technique developed in our departments. This technique is based on irradiation in supine position with the use of asymmetric jaws of the linear accelerator. Results. Radiotherapy was well tolerated and dose-reduction was not needed in any case. Skin reactions were mild in all patients. The gastrointestinal and haematological toxicity was mild to moderate (WHO grade I-II). Conclusion. The proposed new technique of craniospinal irradiation is advantageous in terms of side effects and could be recommended to be widely used. Craniospinal irradiation in supine position is an alternative method to the treatment in prone position. The evaluation of the effectiveness was limited by a short follow-up interval. (author)

The Efficiency of Basalt Fibres in Strengthening the Reinforced Concrete Beams

OpenAIRE

Şerbescu, Andreea; Kypros, Pilakoutas; Ţăranu, N.

2006-01-01

The technique of externally bonding fibre reinforced polymer (FRP) composite laminates on the tension side of reinforced concrete (RC) beams is already widely accepted as an easy to apply, corrosion resistant and effective solution due to the high strength as well as the low weight of the composite material. The basalt fibres are produced from volcano rocks by a simple process; their applicability as reinforcing material composites utilized for plate bonding of RC beams was not enough researc...

The Negative Effects of Positive Reinforcement in Teaching Children with Developmental Delay.

Science.gov (United States)

Biederman, Gerald B.; And Others

1994-01-01

This study compared the performance of 12 children (ages 4 to 10) with developmental delay, each trained in 2 tasks, one through interactive modeling (with or without verbal reinforcement) and the other through passive modeling. Results showed that passive modeling produced better rated performance than interactive modeling and that verbal…

Study on reinforced concrete beams with helical transverse reinforcement

Science.gov (United States)

Kaarthik Krishna, N.; Sandeep, S.; Mini, K. M.

2018-02-01

In a Reinforced Concrete (R.C) structure, major reinforcement is used for taking up tensile stresses acting on the structure due to applied loading. The present paper reports the behavior of reinforced concrete beams with helical reinforcement (transverse reinforcement) subjected to monotonous loading by 3-point flexure test. The results were compared with identically similar reinforced concrete beams with rectangular stirrups. During the test crack evolution, load carrying capacity and deflection of the beams were monitored, analyzed and compared. Test results indicate that the use of helical reinforcement provides enhanced load carrying capacity and a lower deflection proving to be more ductile, clearly indicating the advantage in carrying horizontal loads. An analysis was also carried out using ANSYS software in order to compare the test results of both the beams.

Acoustic emission techniques applied to conventionally reinforced concrete bridge girders : final report.

Science.gov (United States)

2008-09-01

Reinforced concrete (RC) bridges generally operate at service-level loads except during discrete overload events that can reduce the integrity of the structure by initiating concrete cracks, widening or extending of existing concrete cracks, as well ...

Measurement of reinforcement corrosion in marine structures

International Nuclear Information System (INIS)

Mohammad Ismail; Nordin Yahaya

1999-01-01

The marine environment is known to be aggressive. Structures constructed on this belt need to undergo periodic assessment in order to ensure no defects or signs of deterioration had occurred. One of the most common deterioration that occurs on marine structures is corrosion of the reinforcement. Corrosion is an electrochemical process. The product of corrosion can increase the reinforcement volume, hence causing cracking on concrete cover. If no action is taken, delamination and spalling of concrete will follow and this will affect the structures integrity. It is therefore important to know the state of the structures condition by monitoring them periodically. NDT techniques that can detect the occurrence of corrosion of reinforcement in concrete uses half cell and resistivity meter. The method of application and interpretation of results are discussed. (author)

Incomplete factorization technique for positive definite linear systems

International Nuclear Information System (INIS)

Manteuffel, T.A.

1980-01-01

This paper describes a technique for solving the large sparse symmetric linear systems that arise from the application of finite element methods. The technique combines an incomplete factorization method called the shifted incomplete Cholesky factorization with the method of generalized conjugate gradients. The shifted incomplete Cholesky factorization produces a splitting of the matrix A that is dependent upon a parameter α. It is shown that if A is positive definite, then there is some α for which this splitting is possible and that this splitting is at least as good as the Jacobi splitting. The method is shown to be more efficient on a set of test problems than either direct methods or explicit iteration schemes

Continuous Natural Fiber Reinforced Thermoplastic Composites by Fiber Surface Modification

Directory of Open Access Journals (Sweden)

Patcharat Wongsriraksa

2013-01-01

Full Text Available Continuous natural fiber reinforced thermoplastic materials are expected to replace inorganic fiber reinforced thermosetting materials. However, in the process of fabricating the composite, it is difficult to impregnate the thermoplastic resin into reinforcement fiber because of the high melt viscosity. Therefore, intermediate material, which allows high impregnation during molding, has been investigated for fabricating continuous fiber reinforced thermoplastic composite by aligning resin fiber alongside reinforcing fiber with braiding technique. This intermediate material has been called “microbraid yarn (MBY.” Moreover, it is well known that the interfacial properties between natural fiber and resin are low; therefore, surface treatment on continuous natural fiber was performed by using polyurethane (PU and flexible epoxy (FLEX to improve the interfacial properties. The effect of surface treatment on the mechanical properties of continuous natural fiber reinforced thermoplastic composites was examined. From these results, it was suggested that surface treatment by PU with low content could produce composites with better mechanical properties.

Further Examination of Factors that Influence Preference for Positive versus Negative Reinforcement

Science.gov (United States)

Kodak, Tiffany; Lerman, Dorothea C.; Volkert, Valerie M.; Trosclair, Nicole

2007-01-01

Factors that influence choice between qualitatively different reinforcers (e.g., a food item or a break from work) are important to consider when arranging treatments for problem behavior. Previous findings indicate that children who engage in problem behavior maintained by escape from demands may choose a food item over the functional reinforcer…

Reinforced magnesium composites by metallic particles for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Vahid, Alireza; Hodgson, Peter [Institute for Frontier Materials, Deakin University, Geelong, Victoria 3217 (Australia); Li, Yuncang, E-mail: yuncang.li@rmit.edu.au [Institute for Frontier Materials, Deakin University, Geelong, Victoria 3217 (Australia); School of Engineering, RMIT University, Melbourne, Victoria 3001 (Australia)

2017-02-08

Pure magnesium (Mg) implants have unsatisfactory mechanical properties, particularly in loadbearing applications. Particulate-reinforced Mg composites are known as promising materials to provide higher strength implants compared to unreinforced metals. In the current work biocompatible niobium (Nb) and tantalum (Ta) particles are selected as reinforcement, and Mg-Nb and Mg-Ta composites fabricated via a powder metallurgy process associated with the ball milling technique. The effect of Nb and Ta contents on the microstructure and mechanical properties of Mg matrix was investigated. There was a uniform distribution of reinforcements in the Mg matrix with reasonable integrity and no intermetallic formation. The compressive mechanical properties of composites vary with reinforcement contents. The optimal parameters to fabricate biocompatible Mg composites and the optimal composition with appropriate strength, hardness and ductility are recommended.

REINFORCED COMPOSITE PANEL

DEFF Research Database (Denmark)

2003-01-01

A composite panel having front and back faces, the panel comprising facing reinforcement, backing reinforcement and matrix material binding to the facing and backing reinforcements, the facing and backing reinforcements each independently comprising one or more reinforcing sheets, the facing rein...... by matrix material, the facing and backing reinforcements being interconnected to resist out-of-plane relative movement. The reinforced composite panel is useful as a barrier element for shielding structures, equipment and personnel from blast and/or ballistic impact damage....

Recombinase-driver rat lines: tools, techniques, and optogenetic application to dopamine-mediated reinforcement.

Science.gov (United States)

Witten, Ilana B; Steinberg, Elizabeth E; Lee, Soo Yeun; Davidson, Thomas J; Zalocusky, Kelly A; Brodsky, Matthew; Yizhar, Ofer; Cho, Saemi L; Gong, Shiaoching; Ramakrishnan, Charu; Stuber, Garret D; Tye, Kay M; Janak, Patricia H; Deisseroth, Karl

2011-12-08

Currently there is no general approach for achieving specific optogenetic control of genetically defined cell types in rats, which provide a powerful experimental system for numerous established neurophysiological and behavioral paradigms. To overcome this challenge we have generated genetically restricted recombinase-driver rat lines suitable for driving gene expression in specific cell types, expressing Cre recombinase under the control of large genomic regulatory regions (200-300 kb). Multiple tyrosine hydroxylase (Th)::Cre and choline acetyltransferase (Chat)::Cre lines were produced that exhibited specific opsin expression in targeted cell types. We additionally developed methods for utilizing optogenetic tools in freely moving rats and leveraged these technologies to clarify the causal relationship between dopamine (DA) neuron firing and positive reinforcement, observing that optical stimulation of DA neurons in the ventral tegmental area (VTA) of Th::Cre rats is sufficient to support vigorous intracranial self-stimulation (ICSS). These studies complement existing targeting approaches by extending the generalizability of optogenetics to traditionally non-genetically-tractable but vital animal models. Copyright © 2011 Elsevier Inc. All rights reserved.

Practice makes perfect: self-reported adherence a positive marker of inhaler technique maintenance.

Science.gov (United States)

Azzi, Elizabeth; Srour, Pamela; Armour, Carol; Rand, Cynthia; Bosnic-Anticevich, Sinthia

2017-04-24

Poor inhaler technique and non-adherence to treatment are major problems in the management of asthma. Patients can be taught how to achieve good inhaler technique, however maintenance remains problematic, with 50% of patients unable to demonstrate correct technique. The aim of this study was to determine the clinical, patient-related and/or device-related factors that predict inhaler technique maintenance. Data from a quality-controlled longitudinal community care dataset was utilized. 238 patients using preventer medications where included. Data consisted of patient demographics, clinical data, medication-related factors and patient-reported outcomes. Mixed effects logistic regression was used to identify predictors of inhaler technique maintenance at 1 month. The variables found to be independently associated with inhaler technique maintenance using logistic regression (Χ 2 (3,n = 238) = 33.24, p < 0.000) were inhaler technique at Visit 1 (OR 7.1), device type (metered dose inhaler and dry powder inhalers) (OR 2.2) and self-reported adherent behavior in the prior 7 days (OR 1.3). This research is the first to unequivocally establish a predictive relationship between inhaler technique maintenance and actual patient adherence, reinforcing the notion that inhaler technique maintenance is more than just a physical skill. Inhaler technique maintenance has an underlying behavioral component, which future studies need to investigate. BEHAVIORAL ELEMENT TO CORRECT LONG-TERM INHALER TECHNIQUES: Patients who consciously make an effort to perfect asthma inhaler technique will maintain their skills long-term. Elizabeth Azzi at the University of Sydney, Australia, and co-workers further add evidence that there is a strong behavioral component to patients retaining correct inhaler technique over time. Poor inhaler technique can limit asthma control, affecting quality of life and increasing the chances of severe exacerbations. Azzi's team followed 238 patients to

Reinforcement learning in supply chains.

Science.gov (United States)

Valluri, Annapurna; North, Michael J; Macal, Charles M

2009-10-01

Effective management of supply chains creates value and can strategically position companies. In practice, human beings have been found to be both surprisingly successful and disappointingly inept at managing supply chains. The related fields of cognitive psychology and artificial intelligence have postulated a variety of potential mechanisms to explain this behavior. One of the leading candidates is reinforcement learning. This paper applies agent-based modeling to investigate the comparative behavioral consequences of three simple reinforcement learning algorithms in a multi-stage supply chain. For the first time, our findings show that the specific algorithm that is employed can have dramatic effects on the results obtained. Reinforcement learning is found to be valuable in multi-stage supply chains with several learning agents, as independent agents can learn to coordinate their behavior. However, learning in multi-stage supply chains using these postulated approaches from cognitive psychology and artificial intelligence take extremely long time periods to achieve stability which raises questions about their ability to explain behavior in real supply chains. The fact that it takes thousands of periods for agents to learn in this simple multi-agent setting provides new evidence that real world decision makers are unlikely to be using strict reinforcement learning in practice.

Research Review: Dopamine Transfer Deficit: A Neurobiological Theory of Altered Reinforcement Mechanisms in ADHD

Science.gov (United States)

Tripp, Gail; Wickens, Jeff R.

2008-01-01

This review considers the hypothesis that changes in dopamine signalling might account for altered sensitivity to positive reinforcement in children with ADHD. The existing evidence regarding dopamine cell activity in relation to positive reinforcement is reviewed. We focus on the anticipatory firing of dopamine cells brought about by a transfer…

Graphene-Reinforced Metal and Polymer Matrix Composites

Science.gov (United States)

Kasar, Ashish K.; Xiong, Guoping; Menezes, Pradeep L.

2018-06-01

Composites have tremendous applicability due to their excellent capabilities. The performance of composites mainly depends on the reinforcing material applied. Graphene is successful as an efficient reinforcing material due to its versatile as well as superior properties. Even at very low content, graphene can dramatically improve the properties of polymer and metal matrix composites. This article reviews the fabrication followed by mechanical and tribological properties of metal and polymer matrix composites filled with different kinds of graphene, including single-layer, multilayer, and functionalized graphene. Results reported to date in literature indicate that functionalized graphene or graphene oxide-polymer composites are promising materials offering significantly improved strength and frictional properties. A similar trend of improved properties has been observed in case of graphene-metal matrix composites. However, achieving higher graphene loading with uniform dispersion in metal matrix composites remains a challenge. Although graphene-reinforced composites face some challenges, such as understanding the graphene-matrix interaction or fabrication techniques, graphene-reinforced polymer and metal matrix composites have great potential for application in various fields due to their outstanding properties.

Comparing Different Classes of Reinforcement to Increase Expressive Language for Individuals with Autism

Science.gov (United States)

Leaf, Justin B.; Dale, Stephanie; Kassardjian, Alyne; Tsuji, Kathleen H.; Taubman, Mitchell; McEachin, John J.; Leaf, Ronald B.; Oppenheim-Leaf, Misty L.

2014-01-01

One of the basic principles of applied behavior analysis is that behavior change is largely due to that behavior being reinforced. Therefore the use of positive reinforcement is a key component of most behavioral programs for individuals diagnosed with autism. In this study we compared four different classes of reinforcers (i.e., food, praise,…

Rapid acquisition of operant conditioning in 5-day-old rat pups: a new technique articulating suckling-related motor activity and milk reinforcement.

Science.gov (United States)

Arias, Carlos; Spear, Norman E; Molina, Juan Carlos; Molina, Agustin; Molina, Juan Carlos

2007-09-01

Newborn rats are capable of obtaining milk by attaching to a surrogate nipple. During this procedure pups show a gradual increase in head and forelimb movements oriented towards the artificial device that are similar to those observed during nipple attachment. In the present study the probability of execution of these behaviors was analyzed as a function of their contingency with intraoral milk infusion using brief training procedures (15 min). Five-day-old pups were positioned in a smooth surface having access to a touch-sensitive sensor. Physical contact with the sensor activated an infusion pump which served to deliver intraoral milk reinforcement (Paired group). Yoked controls received the reinforcer when Paired neonates touched the sensor. Paired pups trained under a continuous reinforcement schedule emitted significantly more responses than Yoked controls following two (Experiment 1) or one training session (Experiment 2). These differences were also observed during an extinction session conducted immediately after training. The level of maternal deprivation before training (3 or 6 hr) or the volume of milk delivered (1.0 or 1.5 microl per pulse) did not affect acquisition or extinction performances. In addition, it was observed that the rate of responding of Paired pups during the early phase of the extinction session significantly predicted subsequent levels of acceptance of the reinforcer. These results indicate that the frequency of suckling-related behaviors can be rapidly modified by means of associative operant processes. The operant procedure here described represents an alternative tool for the ontogenetic analysis of self-administration or behavior processes of seeking. .

Accurate ocean bottom seismometer positioning method inspired by multilateration technique

Science.gov (United States)

Benazzouz, Omar; Pinheiro, Luis M.; Matias, Luis M. A.; Afilhado, Alexandra; Herold, Daniel; Haines, Seth S.

2018-01-01

The positioning of ocean bottom seismometers (OBS) is a key step in the processing flow of OBS data, especially in the case of self popup types of OBS instruments. The use of first arrivals from airgun shots, rather than relying on the acoustic transponders mounted in the OBS, is becoming a trend and generally leads to more accurate positioning due to the statistics from a large number of shots. In this paper, a linearization of the OBS positioning problem via the multilateration technique is discussed. The discussed linear solution solves jointly for the average water layer velocity and the OBS position using only shot locations and first arrival times as input data.

Modelling root reinforcement in shallow forest soils

Science.gov (United States)

Skaugset, Arne E.

1997-01-01

A hypothesis used to explain the relationship between timber harvesting and landslides is that tree roots add mechanical support to soil, thus increasing soil strength. Upon harvest, the tree roots decay which reduces soil strength and increases the risk of management -induced landslides. The technical literature does not adequately support this hypothesis. Soil strength values attributed to root reinforcement that are in the technical literature are such that forested sites can't fail and all high risk, harvested sites must fail. Both unstable forested sites and stable harvested sites exist, in abundance, in the real world thus, the literature does not adequately describe the real world. An analytical model was developed to calculate soil strength increase due to root reinforcement. Conceptually, the model is composed of a reinforcing element with high tensile strength, i.e. a conifer root, embedded in a material with little tensile strength, i.e. a soil. As the soil fails and deforms, the reinforcing element also deforms and stretches. The lateral deformation of the reinforcing element is treated analytically as a laterally loaded pile in a flexible foundation and the axial deformation is treated as an axially loaded pile. The governing differential equations are solved using finite-difference approximation techniques. The root reinforcement model was tested by comparing the final shape of steel and aluminum rods, parachute cord, wooden dowels, and pine roots in direct shear with predicted shapes from the output of the root reinforcement model. The comparisons were generally satisfactory, were best for parachute cord and wooden dowels, and were poorest for steel and aluminum rods. A parameter study was performed on the root reinforcement model which showed reinforced soil strength increased with increasing root diameter and soil depth. Output from the root reinforcement model showed a strain incompatibility between large and small diameter roots. The peak

Technique for the focal-length measurement of positive lenses using Fizeau interferometry

International Nuclear Information System (INIS)

Pavan Kumar, Yeddanapudi; Chatterjee, Sanjib

2009-01-01

We present what we believe is a new technique for the focal-length measurement of positive lenses using Fizeau interferometery. The technique utilizes the Gaussian lens equation. The image distance is measured interferometrically in terms of the radius of curvature of the image-forming wavefront emerging from the lens. The radii of curvature of the image-forming wavefronts corresponding to two different axial object positions of known separation are measured. The focal length of the lens is determined by solving the equations obtained using the Gaussian lens equation for the two object positions. Results obtained for a corrected doublet lens of a nominal focal length of 200.0 mm with a measurement uncertainty of ±2.5% is presented

The partial-reinforcement extinction effect and the contingent-sampling hypothesis.

Science.gov (United States)

Hochman, Guy; Erev, Ido

2013-12-01

The partial-reinforcement extinction effect (PREE) implies that learning under partial reinforcements is more robust than learning under full reinforcements. While the advantages of partial reinforcements have been well-documented in laboratory studies, field research has failed to support this prediction. In the present study, we aimed to clarify this pattern. Experiment 1 showed that partial reinforcements increase the tendency to select the promoted option during extinction; however, this effect is much smaller than the negative effect of partial reinforcements on the tendency to select the promoted option during the training phase. Experiment 2 demonstrated that the overall effect of partial reinforcements varies inversely with the attractiveness of the alternative to the promoted behavior: The overall effect is negative when the alternative is relatively attractive, and positive when the alternative is relatively unattractive. These results can be captured with a contingent-sampling model assuming that people select options that provided the best payoff in similar past experiences. The best fit was obtained under the assumption that similarity is defined by the sequence of the last four outcomes.

Reinforcement Magnitude: An Evaluation of Preference and Reinforcer Efficacy

OpenAIRE

Trosclair-Lasserre, Nicole M; Lerman, Dorothea C; Call, Nathan A; Addison, Laura R; Kodak, Tiffany

2008-01-01

Consideration of reinforcer magnitude may be important for maximizing the efficacy of treatment for problem behavior. Nonetheless, relatively little is known about children's preferences for different magnitudes of social reinforcement or the extent to which preference is related to differences in reinforcer efficacy. The purpose of the current study was to evaluate the relations among reinforcer magnitude, preference, and efficacy by drawing on the procedures and results of basic experimenta...

Mechanical Performance versus Corrosion Damage Indicators for Corroded Steel Reinforcing Bars

Directory of Open Access Journals (Sweden)

Silvia Caprili

2015-01-01

Full Text Available The experimental results of a testing campaign including tensile and low-cycle fatigue tests on different reinforcing steel bar types in the as-delivered and corroded condition are presented. Experimental data were statistically analyzed adopting ANOVA technique; Performance Indicators (PIs, describing the mechanical performance characteristics of reinforcements, and Corrosion Damage Indicators (CDIs, describing the detrimental effects of corrosion phenomena, were determined and correlated in order to evaluate the influence of corrosion on the behaviour of reinforcing steels, providing useful information for designers in addition to what is presented in current standards.

Reinforced sulphur concrete

NARCIS (Netherlands)

2014-01-01

Reinforced sulphur concrete wherein one or more metal reinforcing members are in contact with sulphur concrete is disclosed. The reinforced sulphur concrete comprises an adhesion promoter that enhances the interaction between the sulphur and the one or more metal reinforcing members.

Study of the stress-strain state of compressed concrete elements with composite reinforcement

Directory of Open Access Journals (Sweden)

Bondarenko Yurii

2017-01-01

Full Text Available The efficiency analysis of the application of glass composite reinforcement in compressed concrete elements as a load-carrying component has been performed. The results of experimental studies of the deformation-strength characteristics of this reinforcement on compression and compressed concrete cylinders reinforced by this reinforcement are presented. The results of tests and mechanisms of sample destruction have been analyzed. The numerical analysis of the stress-strain state has been performed for axial compression of concrete elements with glasscomposite reinforcement. The influence of the reinforcement percentage on the stressed state of a concrete compressed element with the noted reinforcement is estimated. On the basis of the obtained results, it is established that the glass-composite reinforcement has positive effect on the strength of the compressed concrete elements. That is, when calculating the load-bearing capacity of such structures, the function of composite reinforcement on compression should not be neglected.

SYNTHESIS AND CHARACTERIZATION OF CANNABIS INDICA FIBER REINFORCED COMPOSITES

Directory of Open Access Journals (Sweden)

Amar Singh Singha

2011-04-01

Full Text Available This paper reports on the synthesis of Cannabis indica fiber-reinforced composites using Urea-Resorcinol-Formaldehyde (URF as a novel matrix through compression molding technique. The polycondensation between urea, resorcinol, and formaldehyde in different molar ratios was applied to the synthesis of the URF polymer matrix. A thermosetting matrix based composite, reinforced with lignocellulose from Cannabis indica with different fiber loadings 10, 20, 30, 40, and 50% by weight, was obtained. The mechanical properties of randomly oriented intimately mixed fiber particle reinforced composites were determined. Effects of fiber loadings on mechanical properties such as tensile, compressive, flexural strength, and wear resistance were evaluated. Results showed that mechanical properties of URF resin matrix increased considerably when reinforced with particles of Cannabis indica fiber. Thermal (TGA/DTA/DTG and morphological studies (SEM of the resin, fiber and polymer composite thus synthesized were carried out.

Use of extinction and reinforcement to increase food consumption and reduce expulsion.

OpenAIRE

Coe, D A; Babbitt, R L; Williams, K E; Hajimihalis, C; Snyder, A M; Ballard, C; Efron, L A

1997-01-01

Extinction and reinforcement contingencies were used to treat 2 children with feeding disorders. Positive reinforcement and avoidance extinction effectively increased food acceptance but also increased food expulsion. Reduced expulsion and increased swallowing were achieved by repeated presentation of expelled food, a second extinction component

Investigation of a Reinforcement-Based Toilet Training Procedure for Children with Autism.

Science.gov (United States)

Cicero, Frank R.; Pfadt, Al

2002-01-01

This study evaluated the effectiveness of a reinforcement-based toilet training intervention with three children with autism. Procedures included positive reinforcement, graduated guidance, scheduled practice trials, and forward prompting. All three children reduced urination accidents to zero and learned to request bathroom use spontaneously…

Treatment of Multiply Controlled Problem Behavior with Procedural Variations of Differential Reinforcement

Science.gov (United States)

Neidert, Pamela L.; Iwata, Brian A.; Dozier, Claudia L.

2005-01-01

We describe the assessment and treatment of 2 children with autism spectrum disorder whose problem behaviors (self-injury, aggression, and disruption) were multiply controlled. Results of functional analyses indicated that the children's problem behaviors were maintained by both positive reinforcement (attention) and negative reinforcement (escape…

Production and properties of micro-cellulose reinforced thermoplastic starch

Science.gov (United States)

Kmetty, Á.; Karger-Kocsis, J.; Czigány, T.

2015-02-01

Thermoplastic starch (TPS)/micro-fibrillated cellulose (MFC) composites were prepared from maize starch with different amount of distilled water, glycerol and cellulose reinforcement. The components were homogenized by kneader and twin roll technique. The produced TPS and TPS-based polymer composites were qualified by static and dynamic mechanical tests and their morphology was analysed by microscopic techniques. The results showed that the amount of water and the order of the production steps control the properties of both the TPS and its MFC reinforced version. With increasing content of MFC the stiffness and strength of the TPS matrix increased, as expected. Microscopic inspection revealed that the TPS has a homogenous structure and the MFC is well dispersed therein when suitable preparation conditions were selected.

Pattern of parental acceptance of management techniques used in pediatric dentistry.

Science.gov (United States)

Peretz, Benjamin; Kharouba, Johnny; Blumer, Sigalit

2013-01-01

To evaluate parents' acceptance of management techniques in Israeli pediatric dental clinics. Ninety parents who accompanied their children to three pediatric dental clinics provided information on selected parameters including their attitudes about management techniques. 68.9% of the parents preferred to stay in the treatment room. The most accepted technique was positive reinforcement (81.1%) followed by tell-show-do (TSD) (76.7%, with younger parents more accepting than older, p = 0.049). The least accepted techniques were restraint (1.1%) and voice control (7.8%, especially by parents with the highest dental anxiety, p = 0.002). Sedation was unacceptable by 15.6% of the parents: those with the lowest dental anxiety agreed to sedation significantly more than those with greater dental anxiety (p = 0.031). Parents preferred more positive approaches and management techniques that involve demonstrations geared for the child's level of understanding. Restraint and voice control were more strongly rejected than sedation.

How we learn to make decisions: rapid propagation of reinforcement learning prediction errors in humans.

Science.gov (United States)

Krigolson, Olav E; Hassall, Cameron D; Handy, Todd C

2014-03-01

Our ability to make decisions is predicated upon our knowledge of the outcomes of the actions available to us. Reinforcement learning theory posits that actions followed by a reward or punishment acquire value through the computation of prediction errors-discrepancies between the predicted and the actual reward. A multitude of neuroimaging studies have demonstrated that rewards and punishments evoke neural responses that appear to reflect reinforcement learning prediction errors [e.g., Krigolson, O. E., Pierce, L. J., Holroyd, C. B., & Tanaka, J. W. Learning to become an expert: Reinforcement learning and the acquisition of perceptual expertise. Journal of Cognitive Neuroscience, 21, 1833-1840, 2009; Bayer, H. M., & Glimcher, P. W. Midbrain dopamine neurons encode a quantitative reward prediction error signal. Neuron, 47, 129-141, 2005; O'Doherty, J. P. Reward representations and reward-related learning in the human brain: Insights from neuroimaging. Current Opinion in Neurobiology, 14, 769-776, 2004; Holroyd, C. B., & Coles, M. G. H. The neural basis of human error processing: Reinforcement learning, dopamine, and the error-related negativity. Psychological Review, 109, 679-709, 2002]. Here, we used the brain ERP technique to demonstrate that not only do rewards elicit a neural response akin to a prediction error but also that this signal rapidly diminished and propagated to the time of choice presentation with learning. Specifically, in a simple, learnable gambling task, we show that novel rewards elicited a feedback error-related negativity that rapidly decreased in amplitude with learning. Furthermore, we demonstrate the existence of a reward positivity at choice presentation, a previously unreported ERP component that has a similar timing and topography as the feedback error-related negativity that increased in amplitude with learning. The pattern of results we observed mirrored the output of a computational model that we implemented to compute reward

The Effects of Variable-Time Delivery of Food Items and Praise on Problem Behavior Reinforced by Escape

Science.gov (United States)

Lomas, Joanna E.; Fisher, Wayne W.; Kelley, Michael E.

2010-01-01

Prior research indicates that reinforcement of an appropriate response (e.g., compliance) can produce concomitant reductions in problem behavior reinforced by escape when problem behavior continues to produce negative reinforcement (e.g., Lalli et al., 1999). These effects may be due to a preference for positive over negative reinforcement or to…

Reinforcement Magnitude: An Evaluation of Preference and Reinforcer Efficacy

Science.gov (United States)

Trosclair-Lasserre, Nicole M.; Lerman, Dorothea C.; Call, Nathan A.; Addison, Laura R.; Kodak, Tiffany

2008-01-01

Consideration of reinforcer magnitude may be important for maximizing the efficacy of treatment for problem behavior. Nonetheless, relatively little is known about children's preferences for different magnitudes of social reinforcement or the extent to which preference is related to differences in reinforcer efficacy. The purpose of the current…

Autoshaping Chicks with Heat Reinforcement: The Role of Stimulus-Reinforcer and Response-Reinforcer Relations

Science.gov (United States)

Wasserman, Edward A.; And Others

1975-01-01

The present series of experiments attempted to analyze more fully the contributions of stimulus-reinforcer and response-reinforcer relations to autoshaping within a single conditioning situation. (Author)

Protection of Reinforced Concrete Structures of Waste Water Treatment Reservoirs with Stainless Steel Coating Using Arc Thermal Spraying Technique in Acidified Water

Directory of Open Access Journals (Sweden)

Han-Seung Lee

2016-09-01

Full Text Available Waste water treatment reservoirs are contaminated with many hazardous chemicals and acids. Reservoirs typically comprise concrete and reinforcement steel bars, and the main elements responsible for their deterioration are hazardous chemicals, acids, and ozone. Currently, a variety of techniques are being used to protect reservoirs from exposure to these elements. The most widely used techniques are stainless steel plating and polymeric coating. In this study, a technique known as arc thermal spraying was used. It is a more convenient and economical method for protecting both concrete and reinforcement steel bar from deterioration in waste water treatment reservoirs. In this study, 316L stainless steel coating was applied to a concrete surface, and different electrochemical experiments were performed to evaluate the performance of coatings in different acidic pH solutions. The coating generated from the arc thermal spraying process significantly protected the concrete surface from corrosion in acidic pH solutions, owing to the formation of a double layer capacitance—a mixture of Cr3+ enriched with Cr2O3 and Cr-hydroxide in inner and Fe3+ oxide on the outer layer of the coating. The formation of this passive film is defective owing to the non-homogeneous 316L stainless steel coating surface. In the pH 5 solution, the growth of a passive film is adequate due to the presence of un-dissociated water molecules in the aqueous sulfuric acid solution. The coated surface is sealed with alkyl epoxide, which acts as a barrier against the penetration of acidic solutions. This coating exhibits higher impedance values among the three studied acidic pH solutions.

Stripping demolition of concrete by applying electric current through reinforcing bars

International Nuclear Information System (INIS)

Nakagawa, Wahei; Kumegawa, Sadatsune

1995-01-01

The presence of reinforcing bars in reinforced concrete structures is an obstruction hindering the smooth progress of demolition works. The electric heating method is, on the other hand, a demolition technique of unique concept since it adopts the bars to help the demolition of reinforced concrete structures. This technique has the following advantages for demolition: 1) the more densely a structure is reinforced with bars, the greater is the effect of the electric heating, 2) demolition after heating produces little dust, and 3) electric heating of reinforcing bars causes no damage to the portions of concrete not subjected to electric current. The present paper describes the procedures and results of a series of experiments we conducted to verify the efficiency of the electric heating method. In this method, a low-voltage high-current is run through reinforcing bars existing in a concrete structure, inducing intense heat in the bars which in its turn brings about cracks in the surrounding concrete mass, facilitating secondary demolition by hammer picks or other means. The experiments were performed on full-scale biological shield wall mock-ups of a BWR and a small nuclear reactor. The experiments revealed that these excellent features of the electric heating method are worth utilizing in stripping demolition of radioactivated regions of biological shield walls in nuclear power plants. The electric heating method is currently being adopted and shows effective results in partial demolition works in diaphragm wall shafts where starting/arriving holes are to be fixed for shield machines without damaging surrounding portions. (author)

Development of a relationship between external measurements and reinforcement stress

Science.gov (United States)

Brault, Andre; Hoult, Neil A.; Lees, Janet M.

2015-03-01

As many countries around the world face an aging infrastructure crisis, there is an increasing need to develop more accurate monitoring and assessment techniques for reinforced concrete structures. One of the challenges associated with assessing existing infrastructure is correlating externally measured parameters such as crack widths and surface strains with reinforcement stresses as this is dependent on a number of variables. The current research investigates how the use of distributed fiber optic sensors to measure reinforcement strain can be correlated with digital image correlation measurements of crack widths to relate external crack width measurements to reinforcement stresses. An initial set of experiments was undertaken involving a series of small-scale beam specimens tested in three-point bending with variable reinforcement properties. Relationships between crack widths and internal reinforcement strains were observed including that both the diameter and number of bars affected the measured maximum strain and crack width. A model that uses measured crack width to estimate reinforcement strain was presented and compared to the experimental results. The model was found to provide accurate estimates of load carrying capacity for a given crack width, however, the model was potentially less accurate when crack widths were used to estimate the experimental reinforcement strains. The need for more experimental data to validate the conclusions of this research was also highlighted.

Behavioral sensitivity to changing reinforcement contingencies in attention-deficit hyperactivity disorder.

Science.gov (United States)

Alsop, Brent; Furukawa, Emi; Sowerby, Paula; Jensen, Stephanie; Moffat, Cara; Tripp, Gail

2016-08-01

Altered sensitivity to positive reinforcement has been hypothesized to contribute to the symptoms of attention-deficit hyperactivity disorder (ADHD). In this study, we evaluated the ability of children with and without ADHD to adapt their behavior to changing reinforcer availability. Of one hundred sixty-seven children, 97 diagnosed with ADHD completed a signal-detection task in which correct discriminations between two stimuli were associated with different frequencies of reinforcement. The response alternative associated with the higher rate of reinforcement switched twice during the task without warning. For a subset of participants, this was followed by trials for which no reinforcement was delivered, irrespective of performance. Children in both groups developed an initial bias toward the more frequently reinforced response alternative. When the response alternative associated with the higher rate of reinforcement switched, the children's response allocation (bias) followed suit, but this effect was significantly smaller for children with ADHD. When reinforcement was discontinued, only children in the control group modified their response pattern. Children with ADHD adjust their behavioral responses to changing reinforcer availability less than typically developing children, when reinforcement is intermittent and the association between an action and its consequences is uncertain. This may explain the difficulty children with ADHD have adapting their behavior to new situations, with different reinforcement contingencies, in daily life. © 2016 Association for Child and Adolescent Mental Health.

Safe Exploration of State and Action Spaces in Reinforcement Learning

OpenAIRE

Garcia, Javier; Fernandez, Fernando

2014-01-01

In this paper, we consider the important problem of safe exploration in reinforcement learning. While reinforcement learning is well-suited to domains with complex transition dynamics and high-dimensional state-action spaces, an additional challenge is posed by the need for safe and efficient exploration. Traditional exploration techniques are not particularly useful for solving dangerous tasks, where the trial and error process may lead to the selection of actions whose execution in some sta...

Traffic light control by multiagent reinforcement learning systems

NARCIS (Netherlands)

Bakker, B.; Whiteson, S.; Kester, L.; Groen, F.C.A.; Babuška, R.; Groen, F.C.A.

2010-01-01

Traffic light control is one of the main means of controlling road traffic. Improving traffic control is important because it can lead to higher traffic throughput and reduced traffic congestion. This chapter describes multiagent reinforcement learning techniques for automatic optimization of

Traffic Light Control by Multiagent Reinforcement Learning Systems

NARCIS (Netherlands)

Bakker, B.; Whiteson, S.; Kester, L.J.H.M.; Groen, F.C.A.

2010-01-01

Traffic light control is one of the main means of controlling road traffic. Improving traffic control is important because it can lead to higher traffic throughput and reduced traffic congestion. This chapter describes multiagent reinforcement learning techniques for automatic optimization of

VMAT techniques for lymph node-positive left sided breast cancer

International Nuclear Information System (INIS)

Pasler, Marlies; Lutterbach, Johannes; Bjoernsgard, Mari; Reichmann, Ursula; Bartelt, Susanne; Georg, Dietmar; Medical Univ. Vienna

2015-01-01

To investigate the plan quality of two different volumetric modulated arc therapy (VMAT) techniques for lymph node-positive left-sided breast cancer. Two VMAT plans were generated for 10 lymph node-positive left-sided breast cancer patients: one plan using one single segment of a full rotation, typically an arc segment of 230 (1s-VMAT); and a second plan consisting of 2 small tangential arc segments of about 50 (2s-VMAT). For plan comparison, various dose and dose volume metrics (D mean , D 98% , D 2% for target volumes, D 2% , D mean and V x% for organs at risk (OAR)) were evaluated. Both techniques fulfilled both clinical target dose and OAR goals. 1s-VMAT achieved a slightly better homogeneity and better target coverage (D 2% = 54.2 ± 0.7 Gy, D 98% = 30.3 ± 1.8 Gy) compared to 2s-VMAT (D 2% = 55.0 ± 1.1 Gy, D 98% = 29.9 ± 1.7 Gy). For geometrical reasons, OAR sparing was noticeable but not significant better using 2s-VMAT, particularly heart and contralateral breast. The heart received a mean dose of 4.4 ± 0.8 Gy using 1s-VMAT and 3.3 ± 1.0 Gy using 2s-VMAT; the contralateral breast received 1.5 ± 0.3 Gy and 0.9 ± 0.3 Gy, respectively. A VMAT technique based on two small tangential arc segments enables improved OAR sparing; the differences between the two techniques in target coverage and homogeneity are minor. Patient age and -anatomy must be considered for each individual case when deciding which technique to be used.

Pointwise probability reinforcements for robust statistical inference.

Science.gov (United States)

Frénay, Benoît; Verleysen, Michel

2014-02-01

Statistical inference using machine learning techniques may be difficult with small datasets because of abnormally frequent data (AFDs). AFDs are observations that are much more frequent in the training sample that they should be, with respect to their theoretical probability, and include e.g. outliers. Estimates of parameters tend to be biased towards models which support such data. This paper proposes to introduce pointwise probability reinforcements (PPRs): the probability of each observation is reinforced by a PPR and a regularisation allows controlling the amount of reinforcement which compensates for AFDs. The proposed solution is very generic, since it can be used to robustify any statistical inference method which can be formulated as a likelihood maximisation. Experiments show that PPRs can be easily used to tackle regression, classification and projection: models are freed from the influence of outliers. Moreover, outliers can be filtered manually since an abnormality degree is obtained for each observation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Neural mechanisms of negative reinforcement in children and adolescents with autism spectrum disorders

OpenAIRE

Damiano, Cara R; Cockrell, Dillon C; Dunlap, Kaitlyn; Hanna, Eleanor K; Miller, Stephanie; Bizzell, Joshua; Kovac, Megan; Turner-Brown, Lauren; Sideris, John; Kinard, Jessica; Dichter, Gabriel S

2015-01-01

Background Previous research has found accumulating evidence for atypical reward processing in autism spectrum disorders (ASD), particularly in the context of social rewards. Yet, this line of research has focused largely on positive social reinforcement, while little is known about the processing of negative reinforcement in individuals with ASD. Methods The present study examined neural responses to social negative reinforcement (a face displaying negative affect) and non-social negative re...

[Profound meaning of acupuncture taboos in Internal Classic based on the fault of reinforcing and reducing technique by mind conduction of acupuncture therapy].

Science.gov (United States)

Qin, Yuge; Wang, Feng; Qin, Yuheng; Li, Li; Li, Mei

2016-05-01

By analyzing the acupuncture taboos in Neijing (Internal Classic) on clinical application of mind conduction of acupuncture therapy in going against the actual situation, astronomy and others, it is found that the relevant acupuncture taboo implies many subtle mysteries of human body, qi, mind and astronomy, which have not been discovered yet in modern science and are very significant in qi protection. In Neijing, the acupuncture physicians have been highly required in the mind treatment, in which, accurately regulating qi circulation is the target in the treatment. The mind conduction is used for qi circulation to accomplish accurately the reinforcing or reducing in the deficiency or excess condition. All of the taboos are provided to normalize the accuracy of reinforcing and reducing technique of acupuncture therapy and avoid the damage of qi in human body. Hence, those taboos must be obeyed so as to prevent from serious consequence and ensure the safety of this acupuncture therapy.

Non-destructive radiometry inspection technique for locating reinforcements and void/porosity in bridge bearings

International Nuclear Information System (INIS)

Yahaya bin Jafar; Jaafar bin Abdullah; Mohamad Azmi bin Ismail.

1989-01-01

Defects detection in bridge bearings is very important in controlling quality and safety. Typical manufacturing defects include misalligned or bent steel plates and the presence of voids/porosity within the rubber. A non-destructive radiometry inspection technique was used to locate steel plates position and the presence of voids/porosity in bridge bearing samples provided by the Rubber Research Institute of Malaysia (RRIM). Preliminary studies show that the mentioned defects can readily be determined by this technique. Some of the results are also presented. (author)

Genomic Signatures of Reinforcement

Directory of Open Access Journals (Sweden)

Austin G. Garner

2018-04-01

Full Text Available Reinforcement is the process by which selection against hybridization increases reproductive isolation between taxa. Much research has focused on demonstrating the existence of reinforcement, yet relatively little is known about the genetic basis of reinforcement or the evolutionary conditions under which reinforcement can occur. Inspired by reinforcement’s characteristic phenotypic pattern of reproductive trait divergence in sympatry but not in allopatry, we discuss whether reinforcement also leaves a distinct genomic pattern. First, we describe three patterns of genetic variation we expect as a consequence of reinforcement. Then, we discuss a set of alternative processes and complicating factors that may make the identification of reinforcement at the genomic level difficult. Finally, we consider how genomic analyses can be leveraged to inform if and to what extent reinforcement evolved in the face of gene flow between sympatric lineages and between allopatric and sympatric populations of the same lineage. Our major goals are to understand if genome scans for particular patterns of genetic variation could identify reinforcement, isolate the genetic basis of reinforcement, or infer the conditions under which reinforcement evolved.

Genomic Signatures of Reinforcement

Science.gov (United States)

Goulet, Benjamin E.

2018-01-01

Reinforcement is the process by which selection against hybridization increases reproductive isolation between taxa. Much research has focused on demonstrating the existence of reinforcement, yet relatively little is known about the genetic basis of reinforcement or the evolutionary conditions under which reinforcement can occur. Inspired by reinforcement’s characteristic phenotypic pattern of reproductive trait divergence in sympatry but not in allopatry, we discuss whether reinforcement also leaves a distinct genomic pattern. First, we describe three patterns of genetic variation we expect as a consequence of reinforcement. Then, we discuss a set of alternative processes and complicating factors that may make the identification of reinforcement at the genomic level difficult. Finally, we consider how genomic analyses can be leveraged to inform if and to what extent reinforcement evolved in the face of gene flow between sympatric lineages and between allopatric and sympatric populations of the same lineage. Our major goals are to understand if genome scans for particular patterns of genetic variation could identify reinforcement, isolate the genetic basis of reinforcement, or infer the conditions under which reinforcement evolved. PMID:29614048

Experience with dynamic reinforcement rates decreases resistance to extinction.

Science.gov (United States)

Craig, Andrew R; Shahan, Timothy A

2016-03-01

The ability of organisms to detect reinforcer-rate changes in choice preparations is positively related to two factors: the magnitude of the change in rate and the frequency with which rates change. Gallistel (2012) suggested similar rate-detection processes are responsible for decreases in responding during operant extinction. Although effects of magnitude of change in reinforcer rate on resistance to extinction are well known (e.g., the partial-reinforcement-extinction effect), effects of frequency of changes in rate prior to extinction are unknown. Thus, the present experiments examined whether frequency of changes in baseline reinforcer rates impacts resistance to extinction. Pigeons pecked keys for variable-interval food under conditions where reinforcer rates were stable and where they changed within and between sessions. Overall reinforcer rates between conditions were controlled. In Experiment 1, resistance to extinction was lower following exposure to dynamic reinforcement schedules than to static schedules. Experiment 2 showed that resistance to presession feeding, a disruptor that should not involve change-detection processes, was unaffected by baseline-schedule dynamics. These findings are consistent with the suggestion that change detection contributes to extinction. We discuss implications of change-detection processes for extinction of simple and discriminated operant behavior and relate these processes to the behavioral-momentum based approach to understanding extinction. © 2016 Society for the Experimental Analysis of Behavior.

Polarization Induced Deterioration of Reinforced Concrete with CFRP Anode.

Science.gov (United States)

Zhu, Ji-Hua; Wei, Liangliang; Zhu, Miaochang; Sun, Hongfang; Tang, Luping; Xing, Feng

2015-07-15

This paper investigates the deterioration of reinforced concrete with carbon fiber reinforced polymer (CFRP) anode after polarization. The steel in the concrete was first subjected to accelerated corrosion to various extents. Then, a polarization test was performed with the external attached CFRP as the anode and the steel reinforcement as the cathode. Carbon fiber reinforced mortar and conductive carbon paste as contact materials were used to adhere the CFRP anode to the concrete. Two current densities of 1244 and 2488 mA/m², corresponding to the steel reinforcements were applied for 25 days. Electrochemical parameters were monitored during the test period. The deterioration mechanism that occurred at the CFRP/contact material interface was investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The increase of feeding voltage and the failure of bonding was observed during polarization process, which might have resulted from the deterioration of the interface between the contact material and CFRP. The formation and accumulation of NaCl crystals at the contact material/CFRP interface were inferred to be the main causes of the failure at the interface.

Habituation of reinforcer effectiveness

OpenAIRE

David R Lloyd; David R Lloyd; Douglas J Medina; Larry W Hawk; Whitney D Fosco; Jerry B Richards

2014-01-01

In this paper we propose an integrative model of habituation of reinforcer effectiveness (HRE) that links behavioral and neural based explanations of reinforcement. We argue that habituation of reinforcer effectiveness (HRE) is a fundamental property of reinforcing stimuli. Most reinforcement models implicitly suggest that the effectiveness of a reinforcer is stable across repeated presentations. In contrast, an HRE approach predicts decreased effectiveness due to repeated presentation. We ar...

Structural Behavior of Concrete Beams Reinforced with Basalt Fiber Reinforced Polymer (BFRP) Bars

Science.gov (United States)

Ovitigala, Thilan

The main challenge for civil engineers is to provide sustainable, environmentally friendly and financially feasible structures to the society. Finding new materials such as fiber reinforced polymer (FRP) material that can fulfill the above requirements is a must. FRP material was expensive and it was limited to niche markets such as space shuttles and air industry in the 1960s. Over the time, it became cheaper and spread to other industries such as sporting goods in the 1980-1990, and then towards the infrastructure industry. Design and construction guidelines are available for carbon fiber reinforced polymer (CFRP), aramid fiber reinforced polymer (AFRP) and glass fiber reinforced polymer (GFRP) and they are currently used in structural applications. Since FRP is linear elastic brittle material, design guidelines for the steel reinforcement are not valid for FRP materials. Corrosion of steel reinforcement affects the durability of the concrete structures. FRP reinforcement is identified as an alternative to steel reinforcement in corrosive environments. Although basalt fiber reinforced polymer (BFRP) has many advantages over other FRP materials, but limited studies have been done. These studies didn't include larger BFRP bar diameters that are mostly used in practice. Therefore, larger beam sizes with larger BFRP reinforcement bar diameters are needed to investigate the flexural and shear behavior of BFRP reinforced concrete beams. Also, shear behavior of BFRP reinforced concrete beams was not yet studied. Experimental testing of mechanical properties and bond strength of BFRP bars and flexural and shear behavior of BFRP reinforced concrete beams are needed to include BFRP reinforcement bars in the design codes. This study mainly focuses on the use of BFRP bars as internal reinforcement. The test results of the mechanical properties of BFRP reinforcement bars, the bond strength of BFRP reinforcement bars, and the flexural and shear behavior of concrete beams

Characterization and modeling of fiber reinforced concrete for structural applications in beams and plates

DEFF Research Database (Denmark)

Paegle, Ieva

(i.e., stirrups) is investigated in detail using digital image correlation (DIC) measurement technique. The use of steel fibers to replace traditional shear reinforcement is not without precedent in current reinforced concrete design codes. However, more detailed information is provided......Fiber reinforced concrete (FRC) with discrete, short and randomly distributed fibers can be specified and designed for structural applications in flexural members. In certain cases, fibers are used as the only reinforcement, while in other cases fibers are used in combination with a reduced amount...... are considered in structural design, the work presented in this thesis analyzes in detail many commonly used test methods on three types of FRC, including Polypropylene Fiber Reinforced Concrete (PP-FRC), Polyvinyl Alcohol Fiber Reinforced Concrete called Engineered Cementitious Composite (ECC) and Steel Fiber...

VMAT techniques for lymph node-positive left sided breast cancer

Energy Technology Data Exchange (ETDEWEB)

Pasler, Marlies; Lutterbach, Johannes; Bjoernsgard, Mari; Reichmann, Ursula; Bartelt, Susanne [Lake Constance Radiation Oncology Center Singen, Friedrichshafen (Germany); Georg, Dietmar [Medical Univ. Vienna/AKH Vienna (Austria). Dept. of Radiooncology; Medical Univ. Vienna (Austria). Christian Doppler Lab. for Medical Radiation Research for Radiation Oncology

2015-09-01

To investigate the plan quality of two different volumetric modulated arc therapy (VMAT) techniques for lymph node-positive left-sided breast cancer. Two VMAT plans were generated for 10 lymph node-positive left-sided breast cancer patients: one plan using one single segment of a full rotation, typically an arc segment of 230 (1s-VMAT); and a second plan consisting of 2 small tangential arc segments of about 50 (2s-VMAT). For plan comparison, various dose and dose volume metrics (D{sub mean}, D{sub 98%}, D{sub 2%} for target volumes, D{sub 2%}, D{sub mean} and V{sub x%} for organs at risk (OAR)) were evaluated. Both techniques fulfilled both clinical target dose and OAR goals. 1s-VMAT achieved a slightly better homogeneity and better target coverage (D{sub 2%} = 54.2 ± 0.7 Gy, D{sub 98%} = 30.3 ± 1.8 Gy) compared to 2s-VMAT (D{sub 2%} = 55.0 ± 1.1 Gy, D{sub 98%} = 29.9 ± 1.7 Gy). For geometrical reasons, OAR sparing was noticeable but not significant better using 2s-VMAT, particularly heart and contralateral breast. The heart received a mean dose of 4.4 ± 0.8 Gy using 1s-VMAT and 3.3 ± 1.0 Gy using 2s-VMAT; the contralateral breast received 1.5 ± 0.3 Gy and 0.9 ± 0.3 Gy, respectively. A VMAT technique based on two small tangential arc segments enables improved OAR sparing; the differences between the two techniques in target coverage and homogeneity are minor. Patient age and -anatomy must be considered for each individual case when deciding which technique to be used.

Factors that influence the reinforcing value of foods and beverages.

Science.gov (United States)

Temple, Jennifer L

2014-09-01

Behavioral economic principles state that as the cost of a product increases, purchasing or consumption of that product will decrease. To understand the impact of behavioral economics on ingestive behavior, our laboratory utilizes an operant behavior paradigm to measure how much work an individual will engage in to get access to foods and beverages. This task provides an objective measure of the reinforcing value. We have shown that consumption of the same high fat snack food every day for two weeks reduces its reinforcing value in lean individuals, but increases its reinforcing value in a subset of obese individuals. This increase in the reinforcing value of food predicts future weight gain. Similarly, we have shown that repeated intake of caffeinated soda increases its reinforcing value in boys, but not in girls. This increase in reinforcing value is not related to usual caffeine consumption, but may be associated with positive, subjective effects of caffeine that are more likely to be reported by boys than by girls. Because food and beverage reinforcement relates to real-world consumption, it is important to determine factors that increase or decrease the reinforcing value and determine the consequences of these responses. We are especially interested in determining ways to shift the behavioral economic curve in order to develop novel strategies to decrease the reinforcing value of less healthy snack foods and beverages, such as soda, potato chips and candy and to increase the reinforcing value of healthier foods and beverages, such as water, fruits, and vegetables. Copyright © 2014 Elsevier Inc. All rights reserved.

Adapting without reinforcement.

Science.gov (United States)

Kheifets, Aaron; Gallistel, C Randy

2012-11-01

Our data rule out a broad class of behavioral models in which behavioral change is guided by differential reinforcement. To demonstrate this, we showed that the number of reinforcers missed before the subject shifted its behavior was not sufficient to drive behavioral change. What's more, many subjects shifted their behavior to a more optimal strategy even when they had not yet missed a single reinforcer. Naturally, differential reinforcement cannot be said to drive a process that shifts to accommodate to new conditions so adeptly that it doesn't miss a single reinforcer: it would have no input on which to base this shift.

Mechanical characterization of PVA hydrogel to be used as artificial joint cartilage reinforced by irradiation techniques

International Nuclear Information System (INIS)

Bavaresco, Vanessa Petrilli; Zavaglia, Cecilia A.C.; Reis, Marcelo de Carvalho

2002-01-01

Crosslinked networks of polyvinyl alcohol (PVA) produced from PVA aqueous solution and induced by radiation has been recently developed, and their mechanical properties have been studied. These materials are too fragile to be useful for artificial joint cartilage applications, unless reinforced in some way. In this work, the mechanical resistance of PVA hydrogel produced by irradiation techniques was studied. Polyvinyl alcohol films from 15 and 20% w/w aqueous solutions were acetalized by immersing it in an acetalization bath containing aqueous formaldehyde, sulfuric acid and sodium sulfate anhydrous (60:50:300 g) at 60 deg C. The acetalized samples were irradiated (Dynamitron (E = 1,5 MeV)) with 25, 50, 75, 100 kGy doses. Hydrogel samples were characterized by indentation creep test and water swelling. The results obtained in this study suggest the improving of the mechanical properties of the hydrogel by the combination of acetalization and electron beam irradiation, without decreasing in the swelling properties. (author)

Experiment and calculation of reinforced concrete at elevated temperatures

CERN Document Server

Guo, Zhenhai

2011-01-01

Concrete as a construction material goes through both physical and chemical changes under extreme elevated temperatures. As one of the most widely used building materials, it is important that both engineers and architects are able to understand and predict its behavior in under extreme heat conditions. Brief and readable, this book provides the tools and techniques to properly analysis the effects of high temperature of reinforced concrete which will lead to more stable, safer structures. Based on years of the author's research, Reinforced Concrete at Elevated Temperatures four par

Influence of Portland Cement Class on the Corrosion Rate of Steel Reinforcement in Cement Mortar Caused by Penetrating Chloride and Sulfate from the Environment

Directory of Open Access Journals (Sweden)

Bikić, F.

2013-01-01

Full Text Available The influence of portland cement class on the corrosion rate of steel reinforcement in cement mortar caused by penetrating chloride or sulfate from the environment in already hardened cement mortar is investigated in this paper. Three classes of portland cement have been used for the tests, PC 35, PC 45 and PC 55. Cylindrical samples of cement mortar with steel reinfor- cement in the middle were treated 6 months at room temperature in the following solutions: w(SO42- = 2.1 % and w(Cl- = 5 %. Two techniques have been used for testing corrosion rate of steel reinforcement in cement mortar: Tafel extrapolation technique and potentiodynamic polarization technique. Investigations were conducted by potentiostat/galvanostat Princeton Applied Research 263A-2 with the software PowerCORR®. The results of both techniques indi-cate the most active corrosion of steel reinforcement in the samples prepared from cement PC 35 in both treated solutions, while the lowest corrosion of the steel reinforcement was observed in cement samples prepared from cement PC 55. This conclusion was drawn by analyzing the results shown in Figs. 1–4. Comparing corrosion current density of samples, working electrodes, Figs. 1 and 2, Table 2, the results show the most stable corrosion of steel reinforcement in samples prepared from cement PC 55, and the most active corrosion in samples prepared from ce- ment PC 35. The most active corrosion in samples prepared from cement PC 35 is evident from the positions of the open circuit potentials whose values are less for samples prepared from cement PC 35 in both the treated solution, Figs. 1 and 2, Table 2. Comparison of the anodic polarization curves of the working electrodes in both the treated solutions, Figs. 3 and 4, also shows that the intensity of corrosion is the largest for the working electrodes prepared from cement PC 35 and the smallest for the working electrodes prepared from cement PC 55. Investigation results should be

Hydrogel-based reinforcement of 3D bioprinted constructs

NARCIS (Netherlands)

Melchels, FPW; Blokzijl, M M; Levato, R; Peiffer, Q C; de Ruijter, M; Hennink, Wim E.; Vermonden, T.; Malda, J

2016-01-01

Progress within the field of biofabrication is hindered by a lack of suitable hydrogel formulations. Here, we present a novel approach based on a hybrid printing technique to create cellularized 3D printed constructs. The hybrid bioprinting strategy combines a reinforcing gel for mechanical support

Investigations of timing during the schedule and reinforcement intervals with wheel-running reinforcement.

Science.gov (United States)

Belke, Terry W; Christie-Fougere, Melissa M

2006-11-01

Across two experiments, a peak procedure was used to assess the timing of the onset and offset of an opportunity to run as a reinforcer. The first experiment investigated the effect of reinforcer duration on temporal discrimination of the onset of the reinforcement interval. Three male Wistar rats were exposed to fixed-interval (FI) 30-s schedules of wheel-running reinforcement and the duration of the opportunity to run was varied across values of 15, 30, and 60s. Each session consisted of 50 reinforcers and 10 probe trials. Results showed that as reinforcer duration increased, the percentage of postreinforcement pauses longer than the 30-s schedule interval increased. On probe trials, peak response rates occurred near the time of reinforcer delivery and peak times varied with reinforcer duration. In a second experiment, seven female Long-Evans rats were exposed to FI 30-s schedules leading to 30-s opportunities to run. Timing of the onset and offset of the reinforcement period was assessed by probe trials during the schedule interval and during the reinforcement interval in separate conditions. The results provided evidence of timing of the onset, but not the offset of the wheel-running reinforcement period. Further research is required to assess if timing occurs during a wheel-running reinforcement period.

FRP reinforcement of timber structures

OpenAIRE

Schober, Kay-Uwe; Harte, Annette M.; Kliger, Robert; Jockwer, Robert; Xu, Qingfeng; Chen, Jian-Fei

2015-01-01

Timber engineering has advanced over recent decades to offer an alternative to traditional materials and methods. The bonding of fibre reinforced plastics (FRP) with adhesives to timber structures for repair and strengthening has many advantages. However, the lack of established design rules has strongly restrained the use of FRP strengthening in many situations, where these could be a preferable option to most traditional techniques. A significant body of research has been carried out in rec...

Enhancing corrosion resistance of reinforced concrete structures with hybrid fiber reinforced concrete

International Nuclear Information System (INIS)

Blunt, J.; Jen, G.; Ostertag, C.P.

2015-01-01

Highlights: • Reinforced concrete beams were subjected to cyclic flexural loading. • Hybrid fiber reinforced composites were effective in reducing corrosion rates. • Crack resistance due to fibers increased corrosion resistance of steel rebar. • Galvanic corrosion measurements underestimated corrosion rates. • Polarization resistance measurements predicted mass loss more accurately. - Abstract: Service loads well below the yield strength of steel reinforcing bars lead to cracking of reinforced concrete. This paper investigates whether the crack resistance of Hybrid Fiber Reinforced Concrete (HyFRC) reduces the corrosion rate of steel reinforcing bars in concrete after cyclic flexural loading. The reinforcing bars were extracted to examine their surface for corrosion and compare microcell and macrocell corrosion mass loss estimates against direct gravimetric measurements. A delay in corrosion initiation and lower active corrosion rates were observed in the HyFRC beam specimens when compared to reinforced specimens containing plain concrete matrices cycled at the same flexural load

Place preference and vocal learning rely on distinct reinforcers in songbirds.

Science.gov (United States)

Murdoch, Don; Chen, Ruidong; Goldberg, Jesse H

2018-04-30

In reinforcement learning (RL) agents are typically tasked with maximizing a single objective function such as reward. But it remains poorly understood how agents might pursue distinct objectives at once. In machines, multiobjective RL can be achieved by dividing a single agent into multiple sub-agents, each of which is shaped by agent-specific reinforcement, but it remains unknown if animals adopt this strategy. Here we use songbirds to test if navigation and singing, two behaviors with distinct objectives, can be differentially reinforced. We demonstrate that strobe flashes aversively condition place preference but not song syllables. Brief noise bursts aversively condition song syllables but positively reinforce place preference. Thus distinct behavior-generating systems, or agencies, within a single animal can be shaped by correspondingly distinct reinforcement signals. Our findings suggest that spatially segregated vocal circuits can solve a credit assignment problem associated with multiobjective learning.

Technique for Increasing Accuracy of Positioning System of Machine Tools

Directory of Open Access Journals (Sweden)

Sh. Ji

2014-01-01

Full Text Available The aim of research is to improve the accuracy of positioning and processing system using a technique for optimization of pressure diagrams of guides in machine tools. The machining quality is directly related to its accuracy, which characterizes an impact degree of various errors of machines. The accuracy of the positioning system is one of the most significant machining characteristics, which allow accuracy evaluation of processed parts.The literature describes that the working area of the machine layout is rather informative to characterize the effect of the positioning system on the macro-geometry of the part surfaces to be processed. To enhance the static accuracy of the studied machine, in principle, two groups of measures are possible. One of them points toward a decrease of the cutting force component, which overturns the slider moments. Another group of measures is related to the changing sizes of the guide facets, which may lead to their profile change.The study was based on mathematical modeling and optimization of the cutting zone coordinates. And we find the formula to determine the surface pressure of the guides. The selected parameters of optimization are vectors of the cutting force and values of slides and guides. Obtained results show that a technique for optimization of coordinates in the cutting zone was necessary to increase a processing accuracy.The research has established that to define the optimal coordinates of the cutting zone we have to change the sizes of slides, value and coordinates of applied forces, reaching the pressure equalization and improving the accuracy of positioning system of machine tools. In different points of the workspace a vector of forces is applied, pressure diagrams are found, which take into account the changes in the parameters of positioning system, and the pressure diagram equalization to provide the most accuracy of machine tools is achieved.

Effect of reinforcer magnitude on performance maintained by progressive-ratio schedules.

Science.gov (United States)

Rickard, J F; Body, S; Zhang, Z; Bradshaw, C M; Szabadi, E

2009-01-01

This experiment examined the relationship between reinforcer magnitude and quantitative measures of performance on progressive-ratio schedules. Fifteen rats were trained under a progressive-ratio schedule in seven phases of the experiment in which the volume of a 0.6-M sucrose solution reinforcer was varied within the range 6-300 microl. Overall response rates in successive ratios conformed to a bitonic equation derived from Killeen's (1994) Mathematical Principles of Reinforcement. The "specific activation" parameter, a, which is presumed to reflect the incentive value of the reinforcer, was a monotonically increasing function of reinforcer volume; the "response time" parameter, delta, which defines the minimum response time, increased as a function of reinforcer volume; the "currency" parameter, beta, which is presumed to reflect the coupling of responses to the reinforcer, declined as a function of volume. Running response rate (response rate calculated after exclusion of the postreinforcement pause) decayed monotonically as a function of ratio size; the index of curvature of this function increased as a function of reinforcer volume. Postreinforcement pause increased as a function of ratio size. Estimates of a derived from overall response rates and postreinforcement pauses showed a modest positive correlation across conditions and between animals. Implications of the results for the quantification of reinforcer value and for the use of progressive-ratio schedules in behavioral neuroscience are discussed.

CENTRAL REINFORCING EFFECTS OF ETHANOL ARE BLOCKED BY CATALASE INHIBITION

OpenAIRE

Nizhnikov, Michael Edward; Molina, Juan Carlos; Spear, Norman

2007-01-01

Recent studies have systematically indicated that newborn rats are highly sensitive to ethanol’s positive reinforcing effects. Central administrations of ethanol (25–200 mg %) associated with an olfactory conditioned stimulus (CS) promote subsequent conditioned approach to the CS as evaluated through the newborn’s response to a surrogate nipple scented with the CS. It has been shown that ethanol’s first metabolite, acetaldehyde, exerts significant reinforcing effects in the central nervous sy...

Behaviour of reinforced columns with E_Glass fiber and carbon fiber

OpenAIRE

BOUCHELAGHEM Hafida; BEZAZI Abederrezak; Benzanache Naziha; SCARPA Fabrizio

2018-01-01

Externally bonded reinforcement using Fiber Reinforced Polymer (FRP) is a good response to the concern represented by the need for rehabilitation of concrete structures. These techniques are more and more attractive because of their fast and low labour costs, very good strength to weight ratio, good fatigue properties, and non-corrosive characteristics of FRP. The present work is an experimental study investigating the mechanical behaviour under a uni-axial loading of short concrete columns r...

Corrosion detection of steel reinforced concrete using combined carbon fiber and fiber Bragg grating active thermal probe

International Nuclear Information System (INIS)

Li, Weijie; Ho, Siu Chun Michael; Song, Gangbing

2016-01-01

Steel reinforcement corrosion is one of the dominant causes for structural deterioration for reinforced concrete structures. This paper presents a novel corrosion detection technique using an active thermal probe. The technique takes advantage of the fact that corrosion products have poor thermal conductivity, which will impede heat propagation generated from the active thermal probe. At the same time, the active thermal probe records the temperature response. The presence of corrosion products can thus be detected by analyzing the temperature response after the injection of heat at the reinforcement-concrete interface. The feasibility of the proposed technique was firstly analyzed through analytical modeling and finite element simulation. The active thermal probe consisted of carbon fiber strands to generate heat and a fiber optic Bragg grating (FBG) temperature sensor. Carbon fiber strands are used due to their corrosion resistance. Wet-dry cycle accelerated corrosion experiments were performed to study the effect of corrosion products on the temperature response of the reinforced concrete sample. Results suggest a high correlation between corrosion severity and magnitude of the temperature response. The technique has the merits of high accuracy, high efficiency in measurement and excellent embeddability. (paper)

Machining and characterization of self-reinforced polymers

Science.gov (United States)

Deepa, A.; Padmanabhan, K.; Kuppan, P.

2017-11-01

This Paper focuses on obtaining the mechanical properties and the effect of the different machining techniques on self-reinforced composites sample and to derive the best machining method with remarkable properties. Each sample was tested by the Tensile and Flexural tests, fabricated using hot compaction test and those loads were calculated. These composites are machined using conventional methods because of lack of advanced machinery in most of the industries. The advanced non-conventional methods like Abrasive water jet machining were used. These machining techniques are used to get the better output for the composite materials with good mechanical properties compared to conventional methods. But the use of non-conventional methods causes the changes in the work piece, tool properties and more economical compared to the conventional methods. Finding out the best method ideal for the designing of these Self Reinforced Composites with and without defects and the use of Scanning Electron Microscope (SEM) analysis for the comparing the microstructure of the PP and PE samples concludes our process.

Integrative techniques related to positive processes in psychotherapy.

Science.gov (United States)

Cromer, Thomas D

2013-09-01

This review compiles and evaluates a number of therapist interventions that have been found to significantly contribute to positive psychotherapy processes (i.e., increased alliance, patient engagement/satisfaction, and symptomatic improvement). Four forms of intervention are presented: Affect-focused, Supportive, Exploratory, and Patient-Therapist Interaction. The intention of this review is to link specific interventions to applied practice so that integrative clinicians can potentially use these techniques to improve their clinical work. To this end, there is the inclusion of theory and empirical studies from a range of orientations including Emotionally Focused, Psychodynamic, Client-Centered, Cognitive-Behavioral, Interpersonal, Eclectic, and Motivational Interviewing. Each of the four sections will include the theoretical basis and proposed mechanism of change for the intervention, research that supports its positive impact on psychotherapy processes, and conclude with examples demonstrating its use in actual practice. Clinical implications and considerations regarding the use of these interventions will also be presented. 2013 APA, all rights reserved

Percutaneous peritoneovenous shunt positioning: technique and preliminary results

International Nuclear Information System (INIS)

Orsi, Franco; Grasso, Rosario Francesco; Bonomo, Guido; Marinucci, Irene; Monti, Cinzia; Bellomi, Massimo

2002-01-01

Nine peritoneovenous shunts were positioned by percutaneous technique in seven patients with advanced malignancy causing severe refractory ascites, and in two patients with hepatic cirrhosis (one with hepatocarcinoma). In all patients the shunts were percutaneously placed through the subclavian vein in the angiographic suite under digital fluoroscopic guide. No complications directly related to the procedure occurred. The shunt was successfully positioned in all patients in 60 min average time. No patient showed symptoms related to pulmonary overload or to disseminated intravascular coagulation. All patients had a significant improvement of the objective symptoms related to ascites such as respiratory symptoms, dyspepsia, and functional impairment to evacuation describing an improvement of their quality of life. Maximum shunt patency was 273 days. Percutaneous placement of peritoneovenous shunt is a safe, fast, and inexpensive procedure, extremely useful in resolution of refractory ascites, reducing symptoms, and allowing effective palliation, with a great improvement in quality of life. (orig.)

Percutaneous peritoneovenous shunt positioning: technique and preliminary results

Energy Technology Data Exchange (ETDEWEB)

Orsi, Franco; Grasso, Rosario Francesco; Bonomo, Guido; Marinucci, Irene [Division of Radiology, European Institute of Oncology, Milan (Italy); Monti, Cinzia [Institute of Radiology, University of Milan (Italy); Bellomi, Massimo [Division of Radiology, European Institute of Oncology, Milan (Italy); Institute of Radiology, University of Milan (Italy)

2002-05-01

Nine peritoneovenous shunts were positioned by percutaneous technique in seven patients with advanced malignancy causing severe refractory ascites, and in two patients with hepatic cirrhosis (one with hepatocarcinoma). In all patients the shunts were percutaneously placed through the subclavian vein in the angiographic suite under digital fluoroscopic guide. No complications directly related to the procedure occurred. The shunt was successfully positioned in all patients in 60 min average time. No patient showed symptoms related to pulmonary overload or to disseminated intravascular coagulation. All patients had a significant improvement of the objective symptoms related to ascites such as respiratory symptoms, dyspepsia, and functional impairment to evacuation describing an improvement of their quality of life. Maximum shunt patency was 273 days. Percutaneous placement of peritoneovenous shunt is a safe, fast, and inexpensive procedure, extremely useful in resolution of refractory ascites, reducing symptoms, and allowing effective palliation, with a great improvement in quality of life. (orig.)

Efficacy of Thermally Conditioned Sisal FRP Composite on the Shear Characteristics of Reinforced Concrete Beams

Directory of Open Access Journals (Sweden)

Tara Sen

2013-01-01

Full Text Available The development of commercially viable composites based on natural resources for a wide range of applications is on the rise. Efforts include new methods of production and the utilization of natural reinforcements to make biodegradable composites with lignocellulosic fibers, for various engineering applications. In this work, thermal conditioning of woven sisal fibre was carried out, followed by the development of woven sisal fibre reinforced polymer composite system, and its tensile and flexural behaviour was characterized. It was observed that thermal conditioning improved the tensile strength and the flexural strength of the woven sisal fibre composites, which were observed to bear superior values than those in the untreated ones. Then, the efficacy of woven sisal fibre reinforced polymer composite for shear strengthening of reinforced concrete beams was evaluated using two types of techniques: full and strip wrapping techniques. Detailed analysis of the load deflection behaviour and fracture study of reinforced concrete beams strengthened with woven sisal under shearing load were carried out, and it was concluded that woven sisal FRP strengthened beams, underwent very ductile nature of failure, without any delamination or debonding of sisal FRP, and also increased the shear strength and the first crack load of the reinforced concrete beams.

Theoretical and numerical analysis of reinforced concrete beams with confinement reinforcement

Directory of Open Access Journals (Sweden)

R. G. Delalibera

Full Text Available This paper discusses the use of confinement in over-reinforced concrete beams. This reinforcement consists of square stirrups, placed in the compression zone of the beam cross-section, in order to improve its ductility. A parametric numerical study is initially performed, using a finite element computational program that considers the material nonlinearities and the confinement effect. To investigate the influence of the transverse reinforcing ratio on the beam ductility, an experimental program was also conducted. Four over-reinforced beams were tested; three beam specimens with additional transverse reinforcement to confine the beams, and one without it. All specimens were fabricated with a concrete designed for a compressive strength of 25 MPa. The experimental results show that the post-peak ductility factor is proportional to the confining reinforcement ratio, however the same is not observed for the pre-peak ductility factor, which varied randomly with changes in the confining reinforcement ratio. It was also observed from the experiments that the confinement effect tends to be smaller close to the beam neutral axis.

Laparoscopic cholecystectomy poses physical injury risk to surgeons: analysis of hand technique and standing position.

Science.gov (United States)

Youssef, Yassar; Lee, Gyusung; Godinez, Carlos; Sutton, Erica; Klein, Rosemary V; George, Ivan M; Seagull, F Jacob; Park, Adrian

2011-07-01

This study compares surgical techniques and surgeon's standing position during laparoscopic cholecystectomy (LC), investigating each with respect to surgeons' learning, performance, and ergonomics. Little homogeneity exists in LC performance and training. Variations in standing position (side-standing technique vs. between-standing technique) and hand technique (one-handed vs. two-handed) exist. Thirty-two LC procedures performed on a virtual reality simulator were video-recorded and analyzed. Each subject performed four different procedures: one-handed/side-standing, one-handed/between-standing, two-handed/side-standing, and two-handed/between-standing. Physical ergonomics were evaluated using Rapid Upper Limb Assessment (RULA). Mental workload assessment was acquired with the National Aeronautics and Space Administration-Task Load Index (NASA-TLX). Virtual reality (VR) simulator-generated performance evaluation and a subjective survey were analyzed. RULA scores were consistently lower (indicating better ergonomics) for the between-standing technique and higher (indicating worse ergonomics) for the side-standing technique, regardless of whether one- or two-handed. Anatomical scores overall showed side-standing to have a detrimental effect on the upper arms and trunk. The NASA-TLX showed significant association between the side-standing position and high physical demand, effort, and frustration (p<0.05). The two-handed technique in the side-standing position required more effort than the one-handed (p<0.05). No difference in operative time or complication rate was demonstrated among the four procedures. The two-handed/between-standing method was chosen as the best procedure to teach and standardize. Laparoscopic cholecystectomy poses a risk of physical injury to the surgeon. As LC is currently commonly performed in the United States, the left side-standing position may lead to increased physical demand and effort, resulting in ergonomically unsound conditions for

Reinforcement of poly (vinyl alcohol films with alpha-chitin nanowhiskers

Directory of Open Access Journals (Sweden)

Hugo Lisboa

2018-03-01

Full Text Available Abstract Composites Films were produced using Poly (Vinyl Alcohol as the soft material and reinforced with Chitin Nanowhiskers(NWCH as the rigid material. The present work studies the reinforcing mechanisms of NWCH in PVA films, made through a solvent casting technique and characterized for their calorimetric, swelling and mechanical properties. DSC tests revealed a sharp increase of 45 °C in glass transition temperatures with only 1.5% NWCH, while melting temperature had a small increases suggesting an anti-plasticizing effect. Swelling tests revealed decreasing hygoscopy when NWCH volume fraction increases. Estimates for elastic tensile modulus using a model that predicts the formation of a percolating network were not consistent with the experimental data of tensile tests suggesting that contrary to the reinforcement with cellulose nanowhiskers the percolating network is not primarily responsible for the reinforcement of the films. By adjusting the Halpin-Tsai equations, modified by Nielsen it was found that the mechanical properties were mainly influenced by the packing of the NWCH.

Quality assurance patient positioning and immobilization techniques for radiotherapy

International Nuclear Information System (INIS)

Wadhawan, G.S.; Negi, P.S.; Anand, A.K.; Munjal, R.K.; Sinha, S.N.

2007-01-01

Over the last decade the ability to precisely deliver radiotherapy (RT) treatments has advanced dramatically. Imaging technology has evolved to facilitate better target delineation during treatment planning. Treatment delivery techniques have advanced to enable intensity modulated RT (IMRT) treatments that provide radiation doses, tightly conforming to the target volumes. These advancements have been driven by the dual goals of maximizing the radiation dose to the tumor volume while minimizing the radiation dose to the surrounding normal tissue. The ability to expand the use of these techniques to deliver higher doses in fewer fractions is now largely limited by changes in the tumor position from day to day and even during treatment and so the ability to precisely locate the tumor throughout the course of RT has become a topic of concern

A Preliminary Study on Cathodic Prevention in Reinforced Mortar

NARCIS (Netherlands)

Koleva, D.A.; Van Breugel, K.; Mol, J.M.C.; De Wit, J.H.W.

2010-01-01

This work presents the preliminary tests on the performance of cathodic prevention (CPre) in reinforced mortar, subjected to aggressive (10% NaCl environment). Cathodic prevention is an electrochemical technique for minimizing, actually "preventing" any eventual corrosion of the steel bars in

Mechanical properties of nanodiamond-reinforced hydroxyapatite composite coatings deposited by suspension plasma spraying

Science.gov (United States)

Chen, Xiuyong; Zhang, Botao; Gong, Yongfeng; Zhou, Ping; Li, Hua

2018-05-01

Hydroxyapatite (HA) coatings suffer from poor mechanical properties, which can be enhanced via incorporation of secondary bioinert reinforcement material. Nanodiamond (ND) possesses excellent mechanical properties to play the role as reinforcement for improving the mechanical properties of brittle HA bioceramic coatings. The major persistent challenge yet is the development of proper deposition techniques for fabricating the ND reinforced HA coatings. In this study, we present a novel deposition approach by plasma spraying the mixtures of ND suspension and micron-sized HA powder feedstock. The effect of ND reinforcement on the microstructure and the mechanical properties of the coatings such as hardness, adhesive strength and friction coefficient were examined. The results showed that the ND-reinforced HA coatings display lower porosity, fewer unmelted particles and uniform microstructure, in turn leading to significantly enhanced mechanical properties. The study presented a promising approach to fabricate ND-reinforced HA composite coatings on metal-based medical implants for potential clinical application.

Investigation of Corrosion and Cathodic Protection in Reinforced Concrete. I : Application of Electrochemical Techniques

NARCIS (Netherlands)

Koleva, D.A.; De Wit, J.H.W.; Van Breugel, K.; Lodhi, Z.F.; Van Westing, E.

2007-01-01

The electrochemical behavior of steel reinforcement in conditions of corrosion and cathodic protection was studied, using electrochemical impedance spectroscopy (EIS) and compared to reference (noncorroding) conditions. Polarization resistance (PR) method and potentiodynamic polarization (PDP) were

Secure positioning technique based on encrypted visible light map for smart indoor service

Science.gov (United States)

Lee, Yong Up; Jung, Gillyoung

2018-03-01

Indoor visible light (VL) positioning systems for smart indoor services are negatively affected by both cochannel interference from adjacent light sources and VL reception position irregularity in the three-dimensional (3-D) VL channel. A secure positioning methodology based on a two-dimensional (2-D) encrypted VL map is proposed, implemented in prototypes of the specific positioning system, and analyzed based on performance tests. The proposed positioning technique enhances the positioning performance by more than 21.7% compared to the conventional method in real VL positioning tests. Further, the pseudonoise code is found to be the optimal encryption key for secure VL positioning for this smart indoor service.

Neural mechanisms of negative reinforcement in children and adolescents with autism spectrum disorders.

Science.gov (United States)

Damiano, Cara R; Cockrell, Dillon C; Dunlap, Kaitlyn; Hanna, Eleanor K; Miller, Stephanie; Bizzell, Joshua; Kovac, Megan; Turner-Brown, Lauren; Sideris, John; Kinard, Jessica; Dichter, Gabriel S

2015-01-01

Previous research has found accumulating evidence for atypical reward processing in autism spectrum disorders (ASD), particularly in the context of social rewards. Yet, this line of research has focused largely on positive social reinforcement, while little is known about the processing of negative reinforcement in individuals with ASD. The present study examined neural responses to social negative reinforcement (a face displaying negative affect) and non-social negative reinforcement (monetary loss) in children with ASD relative to typically developing children, using functional magnetic resonance imaging (fMRI). We found that children with ASD demonstrated hypoactivation of the right caudate nucleus while anticipating non-social negative reinforcement and hypoactivation of a network of frontostriatal regions (including the nucleus accumbens, caudate nucleus, and putamen) while anticipating social negative reinforcement. In addition, activation of the right caudate nucleus during non-social negative reinforcement was associated with individual differences in social motivation. These results suggest that atypical responding to negative reinforcement in children with ASD may contribute to social motivational deficits in this population.

Carbon fiber reinforced asphalt concrete

International Nuclear Information System (INIS)

Jahromi, Saeed G.

2008-01-01

Fibers are often used in the manufacture of other materials. For many years, they have been utilized extensively in numerous applications in civil engineering. Fiber-reinforcement refers to incorporating materials with desired properties within some other materials lacking those properties. Use of fibers is not a new phenomenon, as the technique of fiber-reinforced bitumen began early as 1950. In all industrialized countries today, nearly all concretes used in construction are reinforced. A multitude of fibers and fiber materials are being introduced in the market regularly. The present paper presents characteristics and properties of carbon fiber-reinforced asphalt mixtures, which improve the performance of pavements. To evaluate the effect of fiber contents on bituminous mixtures, laboratory investigations were carried out on the samples with and without fibers. During the course of this study, various tests were undertaken, applying Marshall Test indirect tensile test, creep test and resistance to fatigue cracking by using repeated load indirect tensile test. Carbon fiber exhibited consistency in results and as such it was observed that the addition of fiber does affect the properties of bituminous mixtures, i.e. an increase in its stability and decrease in the flow value as well as an increase in voids in the mix. Results indicate that fibers have the potential to resist structural distress in pavement, in the wake of growing traffic loads and thus improve fatigue by increasing resistance to cracks or permanent deformation. On the whole, the results show that the addition of carbon fiber will improve some of the mechanical properties like fatigue and deformation in the flexible pavement. (author)

Intranasal oxytocin enhances socially-reinforced learning in rhesus monkeys

Directory of Open Access Journals (Sweden)

Lisa A Parr

2014-09-01

Full Text Available There are currently no drugs approved for the treatment of social deficits associated with autism spectrum disorders (ASD. One hypothesis for these deficits is that individuals with ASD lack the motivation to attend to social cues because those cues are not implicitly rewarding. Therefore, any drug that could enhance the rewarding quality of social stimuli could have a profound impact on the treatment of ASD, and other social disorders. Oxytocin (OT is a neuropeptide that has been effective in enhancing social cognition and social reward in humans. The present study examined the ability of OT to selectively enhance learning after social compared to nonsocial reward in rhesus monkeys, an important species for modeling the neurobiology of social behavior in humans. Monkeys were required to learn an implicit visual matching task after receiving either intranasal (IN OT or Placebo (saline. Correct trials were rewarded with the presentation of positive and negative social (play faces/threat faces or nonsocial (banana/cage locks stimuli, plus food. Incorrect trials were not rewarded. Results demonstrated a strong effect of socially-reinforced learning, monkeys’ performed significantly better when reinforced with social versus nonsocial stimuli. Additionally, socially-reinforced learning was significantly better and occurred faster after IN-OT compared to placebo treatment. Performance in the IN-OT, but not Placebo, condition was also significantly better when the reinforcement stimuli were emotionally positive compared to negative facial expressions. These data support the hypothesis that OT may function to enhance prosocial behavior in primates by increasing the rewarding quality of emotionally positive, social compared to emotionally negative or nonsocial images. These data also support the use of the rhesus monkey as a model for exploring the neurobiological basis of social behavior and its impairment.

Evaluation of the thermal properties of polypropylene reinforced with palm fibers composites

International Nuclear Information System (INIS)

Capri, M.R.; Santana, L.C.; Mulinari, D.R.

2016-01-01

The aim of this study was to characterize polypropylene reinforced with palm composites. Of this form, it was studied physical and chemical modifications of the in nature fibers, washed with hot water and mercerized. The composites of polypropylene reinforced with 5%, 10% and 20% (wt /wt) in nature fibers and mercerized were evaluated thermally. The fibers were characterized by SEM XRD and TGA / DSC techniques. Results revealed that the mercerized fibers presented higher crystallinity when compared to others, as well as increased roughness, facilitating interlacing with the reinforcement matrix. Thermal studies of the fibers showed that the mercerization caused displacement curves paragraph higher temperatures. The composites reinforced with treated fibers presented largest temperatures and enthalpies of degradation. The content of fiber influenced in enthalpy degradation and reduction in fusion temperature. (author)

Cymbopogon citratus and NaNO2 Behaviours in 3.5% NaCl-Immersed Steel-Reinforced Concrete: Implications for Eco-Friendly Corrosion Inhibitor Applications for Steel in Concrete

Directory of Open Access Journals (Sweden)

Joshua Olusegun Okeniyi

2018-01-01

Full Text Available This paper studies behaviours of Cymbopogon citratus leaf-extract and NaNO2, used as equal-mass admixture models, in 3.5% NaCl-immersed steel-reinforced concrete by nondestructive electrochemical methods and by compressive-strength improvement/reduction effects. Corrosion-rate, corrosion-current, and corrosion-potential constitute electrochemical test-techniques while compressive-strength effect investigations followed ASTM C29 and ASTM C33, in experiments using positive-controls for the electrochemical and compressive-strength studies. Analyses of the different electrochemical test-results mostly portrayed agreements on reinforcing-steel anticorrosion effects by the concentrations of natural plant and of chemical admixtures in the saline/marine simulating-environment and in the distilled H2O (electrochemical positive control of steel-reinforced concrete immersions. These indicated that little amount (0.0833% cement for concrete-mixing of Cymbopogon citratus leaf-extract was required for optimal inhibition efficiency, η = 99.35%, on reinforcing-steel corrosion, in the study. Results of compressive-strength change factor also indicated that the 0.0833% Cymbopogon citratus concentration outperformed NaNO2 admixture concentrations also in compressive-strength improvement effects on the NaCl-immersed steel-reinforced concrete. These established implications, from the study, on the suitability of the eco-friendly Cymbopogon citratus leaf-extract for replacing the also highly effective NaNO2 inhibitor of steel-in-concrete corrosion in concrete designed for the saline/marine service-environment.

Effect of reinforcement learning on coordination of multiangent systems

Science.gov (United States)

Bukkapatnam, Satish T. S.; Gao, Greg

2000-12-01

For effective coordination of distributed environments involving multiagent systems, learning ability of each agent in the environment plays a crucial role. In this paper, we develop a simple group learning method based on reinforcement, and study its effect on coordination through application to a supply chain procurement scenario involving a computer manufacturer. Here, all parties are represented by self-interested, autonomous agents, each capable of performing specific simple tasks. They negotiate with each other to perform complex tasks and thus coordinate supply chain procurement. Reinforcement learning is intended to enable each agent to reach a best negotiable price within a shortest possible time. Our simulations of the application scenario under different learning strategies reveals the positive effects of reinforcement learning on an agent's as well as the system's performance.

The effect of reinforcement percentages on properties of copper matrix composites reinforced with TiC particles

Energy Technology Data Exchange (ETDEWEB)

Bagheri, GH.A., E-mail: Gh.a.bagheri65@gmail.com

2016-08-15

In this research, copper matrix composites reinforced with different amounts of titanium carbide particles were produced by mechanical milling and in-situ formation of reinforcements. Morphology and size of milled powders were inspected by scanning electron microscopy (SEM) several times during milling process. Changes in lattice parameter, crystallite size, lattice strain, dislocation density and Gibbs free energy changes (due to increasing in dislocation densities and grain boundaries) in different samples (with different TiC particles contents) were studied by X-Ray Diffraction technique with Cu-kα radiation and using Nelson–Riley method and Williamson–Hall equation. Microstructure of samples after sintering was investigated by FESEM. Finally, densitometry, hardness, determination of electrical resistance and pin on disk wear test were performed and effect of reinforcement percentages on the physical and mechanical properties of composites was studied. Results show incredible improvement in mechanical properties with increasing in TiC value, even though, electrical conductivity dropped off considerably. - Highlights: • Microstructures, mechanical and physical properties of composites have been studied. • Stored Gibbs free energy of dislocations and grain boundaries has been calculated. • Gibbs free energy increased with increasing in titanium percent. • Higher TiC percentage led to better mechanical and unfavorable physical properties.

Flexural strength using Steel Plate, Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) on reinforced concrete beam in building technology

Science.gov (United States)

Tarigan, Johannes; Patra, Fadel Muhammad; Sitorus, Torang

2018-03-01

Reinforced concrete structures are very commonly used in buildings because they are cheaper than the steel structures. But in reality, many concrete structures are damaged, so there are several ways to overcome this problem, by providing reinforcement with Fiber Reinforced Polymer (FRP) and reinforcement with steel plates. Each type of reinforcements has its advantages and disadvantages. In this study, researchers discuss the comparison between flexural strength of reinforced concrete beam using steel plates and Fiber Reinforced Polymer (FRP). In this case, the researchers use Carbon Fiber Reinforced Polymer (CFRP) and Glass Fiber Reinforced Polymer (GFRP) as external reinforcements. The dimension of the beams is 15 x 25 cm with the length of 320 cm. Based on the analytical results, the strength of the beam with CFRP is 1.991 times its initial, GFRP is 1.877 times while with the steel plate is 1.646 times. Based on test results, the strength of the beam with CFRP is 1.444 times its initial, GFRP is 1.333 times while the steel plate is 1.167 times. Based on these test results, the authors conclude that beam with CFRP is the best choice for external reinforcement in building technology than the others.

"Notice of Violation of IEEE Publication Principles" Multiobjective Reinforcement Learning: A Comprehensive Overview.

Science.gov (United States)

Liu, Chunming; Xu, Xin; Hu, Dewen

2013-04-29

Reinforcement learning is a powerful mechanism for enabling agents to learn in an unknown environment, and most reinforcement learning algorithms aim to maximize some numerical value, which represents only one long-term objective. However, multiple long-term objectives are exhibited in many real-world decision and control problems; therefore, recently, there has been growing interest in solving multiobjective reinforcement learning (MORL) problems with multiple conflicting objectives. The aim of this paper is to present a comprehensive overview of MORL. In this paper, the basic architecture, research topics, and naive solutions of MORL are introduced at first. Then, several representative MORL approaches and some important directions of recent research are reviewed. The relationships between MORL and other related research are also discussed, which include multiobjective optimization, hierarchical reinforcement learning, and multi-agent reinforcement learning. Finally, research challenges and open problems of MORL techniques are highlighted.

An evaluation of two differential reinforcement procedures with escape extinction to treat food refusal.

Science.gov (United States)

Patel, Meeta R; Piazza, Cathleen C; Martinez, Cheryl J; Volkert, Valerie M; Christine, M Santana

2002-01-01

Consumption of solids and liquids occurs as a chain of behaviors that may include accepting, swallowing, and retaining the food or drink. In the current investigation, we evaluated the relative effectiveness of differential reinforcement of the first behavior in the chain (acceptance) versus differential reinforcement for the terminal behavior in the chain (mouth clean). Three children who had been diagnosed with a feeding disorder participated. Acceptance remained at zero when differential reinforcement contingencies were implemented for acceptance or mouth clean. Acceptance and mouth clean increased for all 3 participants once escape extinction was added to the differential reinforcement procedures, independent of whether reinforcement was provided for acceptance or for mouth clean. Maintenance was observed in 2 children when escape extinction was removed from the treatment package. The mechanism by which consumption increased is discussed in relation to positive and negative reinforcement contingencies.

Central reinforcing effects of ethanol are blocked by catalase inhibition.

Science.gov (United States)

Nizhnikov, Michael E; Molina, Juan C; Spear, Norman E

2007-11-01

Recent studies have systematically indicated that newborn rats are highly sensitive to ethanol's positive reinforcing effects. Central administrations of ethanol (25-200mg %) associated with an olfactory conditioned stimulus (CS) promote subsequent conditioned approach to the CS as evaluated through the newborn's response to a surrogate nipple scented with the CS. It has been shown that ethanol's first metabolite, acetaldehyde, exerts significant reinforcing effects in the central nervous system. A significant amount of acetaldehyde is derived from ethanol metabolism via the catalase system. In newborn rats, catalase levels are particularly high in several brain structures. The present study tested the effect of catalase inhibition on central ethanol reinforcement. In the first experiment, pups experienced lemon odor either paired or unpaired with intracisternal (IC) administrations of 100mg% ethanol. Half of the animals corresponding to each learning condition were pretreated with IC administrations of either physiological saline or a catalase inhibitor (sodium-azide). Catalase inhibition completely suppressed ethanol reinforcement in paired groups without affecting responsiveness to the CS during conditioning or responding by unpaired control groups. A second experiment tested whether these effects were specific to ethanol reinforcement or due instead to general impairment in learning and expression capabilities. Central administration of an endogenous kappa opioid receptor agonist (dynorphin A-13) was used as an alternative source of reinforcement. Inhibition of the catalase system had no effect on the reinforcing properties of dynorphin. The present results support the hypothesis that ethanol metabolism regulated by the catalase system plays a critical role in determination of ethanol reinforcement in newborn rats.

Constructive solutions for beamless capitalless floors with prestressed reinforcement

Directory of Open Access Journals (Sweden)

Bardysheva Yuliya Anatol'evna

2014-07-01

Full Text Available In the article the authors present advanced constructions of prestressed reinforced concrete flat ceiling, where high-strength ropes in elastic shell are used as stressed reinforcement. The novelty of the solution lays in diagonal arrangement of hard valves and use of high-strength ropes in a flexible shell of "Monostrand" type. This type of prestress, in our opinion, is the most acceptable from technical point of view for selective reinforcement of separate tense rods or cables. The use of pre-stressed reinforcement in the form of individual rods or cables increases the rigidity and crack resistance of concrete beamless slabs. The use of high-strength ropes in the monostrand-type shell makes it possible to prestress in frames of single cell plate or floor in general and to reduce labour input for stressing armature. The paper presents original solution with diagonal position of the valve. The authors suggest the use of prestressed diagonal valves as in all cells of the floor with the cells of the same or only slightly different size and in separate cells of the floor (for roofs with different cells. The diagonal location of stressed reinforcement proposed in the work is an efficient solution for extending the range of dimensions and loads size.

Prediction of punching shear capacities of two-way concrete slabs reinforced with FRP bars

Directory of Open Access Journals (Sweden)

Ibrahim M. Metwally

2013-08-01

Full Text Available Where corrosion of steel reinforcement is a concern, fiber-reinforced polymer (FRP reinforcing bar or grid reinforcement provides an alternative reinforcement for concrete flat slabs. The existing provisions for punching of slabs in most international design standards for reinforced concrete are based on tests of steel reinforced slabs. The elastic stiffness and bonding characteristics of FRP reinforcement are sufficiently different from those of steel to affect punching strength [1]. This paper evaluates the punching shear strength of concrete flat slabs reinforced with different types of fiber-reinforced polymer (FRP. A total of 59 full-size slabs were constructed and tested collected from the literature of FRP bars reinforced concrete slabs. The test parameters were the amount of FRP reinforcing bars, Young’s modulus of FRP bars, slab thickness, loaded areas and concrete compressive strength. The experimental punching shear strengths were compared with the available theoretical predictions, including the ACI 318 Code, BS 8110 Code, ACI 440 design guidelines, and a number of models proposed by some researchers in the literature. Two approaches for predicting the punching strength of FRP-reinforced slabs are examined. The first is an empirical new model which is considered as a modification of El-Gamal et al. [2] model. The second is a Neural Networks Technique; which has been developed to predict the punching shear capacity of FRP reinforced concrete slabs. The accuracies of both methods were evaluated against the experimental test data. They attained excellent agreement with available test results compared to the existing design formulas.

Innovative Materials and Techniques in Concrete Construction : ACES Workshop

CERN Document Server

2012-01-01

Recent years have seen enormous advances in the technology of concrete as a material, through which its strength, compactness and ductility can reach levels never dreamed of before. Thanks to these improved material properties, the strength and durability of concrete structures is greatly improved, their weight and dimensions reduced, the scope of concrete as a structural material is widened and – despite the higher material costs – overall economy is possible, with positive impacts on sustainability as well. Similar advances are underway in reinforcing materials, notably high strength steel and fibre-reinforced polymers, and in the way they are combined with concrete into high performance structures. Developments in materials and equipment, as well as new concepts, have lead to innovative construction techniques, reducing cost and construction time and making possible the application of concrete under extreme conditions of construction or environment. All these advances will be highlighted in the book by...

Strength of normal sections of NPP composite monolithic constructions with ribbed reinforced panels

International Nuclear Information System (INIS)

Klyashitskij, V.I.; Kirillov, A.P.

1980-01-01

Strength characteristics and recommendations on designing composite-monolytic structures of NPP with ribbed reinforced panels are considered. Ribbed reinforced panel consists of a system of cross ribs joined with a comparatively thin (25 mm thick) plate. The investigations were carried on using models representing columns symmetrically reinforced with reinforced panels with a low percent of reinforcing. The monolithic structures consisting of ribbed reinforced panels and cast concrete for making monoliths as well as monolithic having analogous strength characteristics of extended and compressed zones have similar strengths. It is shown that calculation of supporting power of composite-monolithic structures is performed according to techniques developed for monolithic structures. Necessity of structural transverse fittings no longer arises in case of corresponding calculational substitution of stability of compressed parts of fittings. Supporting power of a structure decreases not more than by 10% in the presence of cracks in the reinforced panels of the compressed zone. Application of composite-monolithic structures during the construction of the Kursk, Smolensk and Chernobylskaya NPPs permitted to decrease labour content and reduce periods of accomplishment of these works which saves over 6 million roubles

Foot positioning instruction, initial vertical load position and lifting technique: effects on low back loading.

Science.gov (United States)

Kingma, Idsart; Bosch, Tim; Bruins, Louis; van Dieën, Jaap H

2004-10-22

This study investigated the effects of initial load height and foot placement instruction in four lifting techniques: free, stoop (bending the back), squat (bending the knees) and a modified squat technique (bending the knees and rotating them outward). A 2D dynamic linked segment model was combined with an EMG assisted trunk muscle model to quantify kinematics and low back loading in 10 subjects performing 19 different lifting movements, using 10.5 kg boxes without handles. When lifting from a 0.05 m height with the feet behind the box, squat lifting resulted in 19.9% (SD 8.7%) higher net moments (p squat and stoop lifts, as well as the interaction with lifting height, could to a large extent be explained by changes in the horizontal L5/S1 intervertebral joint position relative to the load, the upper body acceleration, and lumbar flexion. Rotating the knees outward during squat lifts resulted in moments and compression forces that were smaller than in squat lifting but larger than in stoop lifting. Shear forces were small ( < 300 N) at the L4/L5 joint and substantial (1100 - 1400 N) but unaffected by lifting technique at the L5/S1 joint. The present results show that the effects of lifting technique on low back loading depend on the task context.

Mathematical modeling for corrosion environment estimation based on concrete resistivity measurement directly above reinforcement

International Nuclear Information System (INIS)

Lim, Young-Chul; Lee, Han-Seung; Noguchi, Takafumi

2009-01-01

This study aims to formulate a resistivity model whereby the concrete resistivity expressing the environment of steel reinforcement can be directly estimated and evaluated based on measurement immediately above reinforcement as a method of evaluating corrosion deterioration in reinforced concrete structures. It also aims to provide a theoretical ground for the feasibility of durability evaluation by electric non-destructive techniques with no need for chipping of cover concrete. This Resistivity Estimation Model (REM), which is a mathematical model using the mirror method, combines conventional four-electrode measurement of resistivity with geometric parameters including cover depth, bar diameter, and electrode intervals. This model was verified by estimation using this model at areas directly above reinforcement and resistivity measurement at areas unaffected by reinforcement in regard to the assessment of the concrete resistivity. Both results strongly correlated, proving the validity of this model. It is expected to be applicable to laboratory study and field diagnosis regarding reinforcement corrosion. (author)

Feasibility of externally activated self-repairing concrete with epoxy injection network and Cu-Al-Mn superelastic alloy reinforcing bars

International Nuclear Information System (INIS)

Pareek, Sanjay; Shrestha, Kshitij C; Araki, Yoshikazu; Suzuki, Yusuke; Omori, Toshihiro; Kainuma, Ryosuke

2014-01-01

This paper studies the effectiveness of an externally activated self-repairing technique for concrete members with epoxy injection network and Cu-Al-Mn superelastic alloy (SEA) reinforcing bars (rebars). Compared to existing crack self-repairing and self-healing techniques, the epoxy injection network has the following strengths: (1) Different from the self-repairing methods using brittle containers or tubes for adhesives, the proposed self-repair process can be performed repeatedly and is feasible for onsite concrete casting. (2) Different from the autogenic self-healing techniques, full strength recovery can be achieved in a shorter time period without the necessity of water. This paper attempts to enhance the self-repairing capability of the epoxy injection network by reducing residual cracks by using cost-effective Cu-based SEA bars. The effectiveness of the present technique is examined using concrete beam specimens reinforced by 3 types of bars. The first specimen is reinforced by steel deformed bars, the second by steel threaded bars, and finally by SEA threaded rebars. The tests were performed with a 3 point cyclic loading with increasing amplitude. From the test results, effective self-repairing was confirmed for small deformation levels irrespective of the reinforcement types. Effective self-repairing was observed in the SEA reinforced specimen even under much larger deformations. Nonlinear finite element analysis was performed to confirm the experimental findings. (paper)

A study on the fatigue strength behavior of reinforced concrete structures

International Nuclear Information System (INIS)

Chang, D.; Chae, W.K.; Kwak, K.H.

1989-01-01

Design methods for shear have been developed in these days.However, these are mainly based on the test results under static loading, and there are few information concerning the shear behavior of reinforced concrete beams under repeated dynamic loading. From this point of view, this study was performed to investigate the shear behavior of four reinforced concrete beams with web reinforcement under repeated dynamic loading. From these test results, the changes in strain of stirrups and the crack propagation procedures are found as functions of the number of repeated loading cycles. These results are compared with the existing experimental formula for predicting strain of stirrups under repeated loading and also used to find the coefficients in the empirical formula using the regression technique

Metal Matrix Composites Reinforced by Nano-Particles—A Review

Directory of Open Access Journals (Sweden)

Riccardo Casati

2014-03-01

Full Text Available Metal matrix composites reinforced by nano-particles are very promising materials, suitable for a large number of applications. These composites consist of a metal matrix filled with nano-particles featuring physical and mechanical properties very different from those of the matrix. The nano-particles can improve the base material in terms of wear resistance, damping properties and mechanical strength. Different kinds of metals, predominantly Al, Mg and Cu, have been employed for the production of composites reinforced by nano-ceramic particles such as carbides, nitrides, oxides as well as carbon nanotubes. The main issue of concern for the synthesis of these materials consists in the low wettability of the reinforcement phase by the molten metal, which does not allow the synthesis by conventional casting methods. Several alternative routes have been presented in literature for the production of nano-composites. This work is aimed at reviewing the most important manufacturing techniques used for the synthesis of bulk metal matrix nanocomposites. Moreover, the strengthening mechanisms responsible for the improvement of mechanical properties of nano-reinforced metal matrix composites have been reviewed and the main potential applications of this new class of materials are envisaged.

A novel microbond bundle pullout technique to evaluate the ...

Indian Academy of Sciences (India)

... pullout technique to evaluate the interfacial properties of fibre-reinforced plastic composites ... https://www.ias.ac.in/article/fulltext/boms/040/04/0737-0744. Keywords. Microbond bundle pullout test; carbon/epoxy; fibre-reinforced composites; ...

Experimental analysis of reinforced concrete beams strengthened in bending with carbon fiber reinforced polymer

Directory of Open Access Journals (Sweden)

M. M. VIEIRA

Full Text Available The use of carbon fiber reinforced polymer (CFRP has been widely used for the reinforcement of concrete structures due to its practicality and versatility in application, low weight, high tensile strength and corrosion resistance. Some construction companies use CFRP in flexural strengthening of reinforced concrete beams, but without anchor systems. Therefore, the aim of this study is analyze, through an experimental program, the structural behavior of reinforced concrete beams flexural strengthened by CFRP without anchor fibers, varying steel reinforcement and the amount of carbon fibers reinforcement layers. Thus, two groups of reinforced concrete beams were produced with the same geometric feature but with different steel reinforcement. Each group had five beams: one that is not reinforced with CFRP (reference and other reinforced with two, three, four and five layers of carbon fibers. Beams were designed using a computational routine developed in MAPLE software and subsequently tested in 4-point points flexural test up to collapse. Experimental tests have confirmed the effectiveness of the reinforcement, ratifying that beams collapse at higher loads and lower deformation as the amount of fibers in the reinforcing layers increased. However, the increase in the number of layers did not provide a significant increase in the performance of strengthened beams, indicating that it was not possible to take full advantage of strengthening applied due to the occurrence of premature failure mode in the strengthened beams for pullout of the cover that could have been avoided through the use of a suitable anchoring system for CFRP.

Development of Composite Made of HDPE and Fiber Reinforced Polymer Dust

International Nuclear Information System (INIS)

Muhamad Noor Izwan Ishak; Ismail Mustapha; Mohd Reusmazran Yusof; Yusof Abdullah; Nor Pai'za Mohamad Hasan; Mohamad Ridzuan Ahamad; Md Fakarudin Ab Rahman; Hafizal Yazid; Ainul Mardhiah Terry; Airwan Affandi Mahmood; Nurliyana Abdullah

2016-01-01

Full text: Composite of High Density Polyethylene and Fiber Reinforced Polymer Dust (HDPE/ FRPD) were prepared by melt mixing technique. The blend was mixed and compression molded by hydraulic press at 150 degree Celsius. Effect of blend ratio on mechanical properties of the developed composite was determined. Tensile properties of the blends found to show decreasing trend with addition of FRPD. While impact strength and hardness properties showed promising result. Reuse of ' Fiber Reinforced Polymer ' dust can be improved by the present invention. (author)

Infrared processed Cu composites reinforced with WC particles

International Nuclear Information System (INIS)

Deshpande, P.K.; Li, J.H.; Lin, R.Y.

2006-01-01

Copper matrix composites with WC particle reinforcements have been prepared with an innovative infrared infiltration technique. The volume content of the reinforcement particles in the composite is about 53%. The relative composite density of as high as 99.9% has been obtained with this process. The electric conductivity of composites prepared in this study as determined by a four-point probe method, is similar to commercially available Cu/W composites containing 52 vol% tungsten. Microhardness, microstructure and wear resistance of the composites were also determined. The microstructure of Cu/WC composite reveals excellent wetting between the two constituent phases, WC and copper. The microhardness values of all completely infiltrated Cu/WC composites were in the range of 360-370 HV which is significantly higher than the microhardness of pure copper, 65 HV. Wear resistance of the composites was determined with a pin on disk wear test technique. The wear test results show that composites prepared in this study performed much better than those commercially available Cu/W composites by more than two-fold against silicon carbide abrasive disks

Acoustic emission of fire damaged fiber reinforced concrete

Science.gov (United States)

Mpalaskas, A. C.; Matikas, T. E.; Aggelis, D. G.

2016-04-01

The mechanical behavior of a fiber-reinforced concrete after extensive thermal damage is studied in this paper. Undulated steel fibers have been used for reinforcement. After being exposed to direct fire action at the temperature of 850°C, specimens were subjected to bending and compression in order to determine the loss of strength and stiffness in comparison to intact specimens and between the two types. The fire damage was assessed using nondestructive evaluation techniques, specifically ultrasonic pulse velocity (UPV) and acoustic emission (AE). Apart from the strong, well known, correlation of UPV to strength (both bending and compressive), AE parameters based mainly on the frequency and duration of the emitted signals after cracking events showed a similar or, in certain cases, better correlation with the mechanical parameters and temperature. This demonstrates the sensitivity of AE to the fracture incidents which eventually lead to failure of the material and it is encouraging for potential in-situ use of the technique, where it could provide indices with additional characterization capability concerning the mechanical performance of concrete after it subjected to fire.

Fun While Learning and Earning. A Look Into Chattanooga Public Schools' Token Reinforcement Program.

Science.gov (United States)

Smith, William F.; Sanders, Frank J.

A token reinforcement program was used by the Piney Woods Research and Demonstration Center in Chattanooga, Tennessee. Children who were from economically deprived homes received tokens for positive behavior. The tokens were redeemable for recess privileges, ice cream, candy, and other such reinforcers. All tokens were spent on the day earned so…

Investigation of a reinforcement-based toilet training procedure for children with autism.

Science.gov (United States)

Cicero, Frank R; Pfadt, Al

2002-01-01

Independent toileting is an important developmental skill which individuals with developmental disabilities often find a challenge to master. Effective toilet training interventions have been designed which rely on a combination of basic operant principles of positive reinforcement and punishment. In the present study, the effectiveness of a reinforcement-based toilet training intervention was investigated with three children with a diagnosis of autism. Procedures included a combination of positive reinforcement, graduated guidance, scheduled practice trials and forward prompting. Results indicated that all procedures were implemented in response to urination accidents. A three participants reduced urination accidents to zero and learned to spontaneously request use of the bathroom within 7-11 days of training. Gains were maintained over 6-month and 1-year follow-ups. Findings suggest that the proposed procedure is an effective and rapid method of toilet training, which can be implemented within a structured school setting with generalization to the home environment.

Studies on mechanical, thermal and dynamic mechanical properties of untreated (raw) and treated coconut sheath fiber reinforced epoxy composites

International Nuclear Information System (INIS)

Suresh Kumar, S.M.; Duraibabu, D.; Subramanian, K.

2014-01-01

Highlights: • UTCSE and TCSE composites have been fabricated by compression molding technique. • The prepared specimens were characterized by FTIR, DMA, TGA and SEM techniques. • TCSE composite showed higher mechanical properties compared to UTCSE composite. • DMA showed that TCSE composite exhibited higher storage modulus than UTCSE composite. • TCSE composite showed higher thermal stability than UTCSE composite. - Abstract: The untreated (raw) coconut sheath fiber reinforced epoxy (UTCSE) composite and treated coconut sheath fiber reinforced epoxy (TCSE) composite have been fabricated using hand layup followed by compression molding technique. The prepared specimens were characterized by Fourier transform infrared spectroscopy (FTIR), dynamic mechanical analysis (DMA), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM) techniques. The prepared specimens are cut as per ASTM Standards to measure tensile, flexural and impact strengths by using universal testing machine and izod impact tester respectively. The treated coconut sheath fiber reinforced epoxy composite (TCSE) posses higher mechanical strength and thermal stability compared to untreated (raw) coconut sheath fiber reinforced epoxy composite (UTCSE). In the SEM fracture analysis, TCSE composite showed better fiber–matrix bonding and absence of voids compared to UTCSE composite

Positive Parenting and Challenging Children

Science.gov (United States)

Knoll, Melissa

2007-01-01

Positive parenting focuses on developing proactive ways to teach and reinforce desirable behaviors, as opposed to focusing on reacting to and attempting to decrease negative behaviors. Dr. Sheldon Braaten, Executive Director of Behavioral Institute for Children and Adolescents, offers some keys for setting up and using a positive reinforcement…

Learning to Play in a Day: Faster Deep Reinforcement Learning by Optimality Tightening

OpenAIRE

He, Frank S.; Liu, Yang; Schwing, Alexander G.; Peng, Jian

2016-01-01

We propose a novel training algorithm for reinforcement learning which combines the strength of deep Q-learning with a constrained optimization approach to tighten optimality and encourage faster reward propagation. Our novel technique makes deep reinforcement learning more practical by drastically reducing the training time. We evaluate the performance of our approach on the 49 games of the challenging Arcade Learning Environment, and report significant improvements in both training time and...

Incremental dynamic analysis of concrete moment resisting frames reinforced with shape memory composite bars

International Nuclear Information System (INIS)

Zafar, Adeel; Andrawes, Bassem

2012-01-01

Fiber reinforced polymer (FRP) reinforcing bars have been used in concrete structures as an alternative to conventional steel reinforcement, in order to overcome corrosion problems. However, due to the linear behavior of the commonly used reinforcing fibers, they are not considered in structures which require ductility and damping characteristics. The use of superelastic shape memory alloy (SMA) fibers with their nonlinear elastic behavior as reinforcement in the composite could potentially provide a solution for this problem. Small diameter SMA wires are coupled with polymer matrix to produce SMA–FRP composite, which is sought in this research as reinforcing bars. SMA–FRP bars are sought in this study to enhance the seismic performance of reinforced concrete (RC) moment resisting frames (MRFs) in terms of reducing their residual inter-story drifts while still maintaining the elastic characteristics associated with conventional FRP. Three story one bay and six story two bay RC MRF prototype structures are designed with steel, SMA–FRP and glass–FRP reinforcement. The incremental dynamic analysis technique is used to investigate the behaviors of the two frames with the three different reinforcement types under a suite of ground motion records. It is found that the frames with SMA–FRP composite reinforcement exhibit higher performance levels including lower residual inter-story drifts, high energy dissipation and thus lower damage, which are important for structures in highly seismic zones. (paper)

Suture-free and mesh reinforced small intestinal anstomoses: a feasibility study in rabbits.

Science.gov (United States)

Ulmer, T F; Stumpf, M; Rosch, R; Junge, K; Binnebösel, M; von Trotha, K T; Oettinger, A P; Neumann, U

2013-08-01

Anastomotic leakage still remains a major complication in general surgery. Beside general risk factors, the ideal method of anastomotic technique has not been found until now. The aim of the present study was to analyze wound healing in suture-free small intestine anastomoses using fibrin glue with and without mesh-reinforcement. Laparotomy and four different types of small bowel anastomoses were performed in 32 chinchilla rabbits. Standard hand-sewn anastomoses (CG), suture-free glued anastomoses (FG) with and without mesh reinforcement using two different types of meshes [Vicryl-mesh (VM) and Surgisis (SM)]. Animals were sacrificed after 5 and 21 days. Bursting pressure, collagen type I/III ratio, and matrix-metalloproteinase 2, 9, and 13 were analyzed. None of the animals died due to an anastomotic leakage. All animals in the long term group with Surgisis mesh died due to a mechanical bowel obstruction based on a distinctive stenosis of the anastomosis. The bursting pressures did significantly differed in animals with fibrin glue alone compared to animals with Vicryl-mesh reinforcement (p < 0.05). Histological examination revealed statistically significant differences (p < 0.05) in the values for MMP-2 (VM < SM), MMP-9 (VM < CG), and MMP-13 (CG < SM, VM < FG, and VM < SM). However, collagen type I/III ratios were not significantly different between groups. Our results suggest that a mesh reinforced glued anastomosis is technically feasible. Furthermore, mesh-reinforcement using VM increased the integrity and simplified the technique of suture-free anastomoses.

CT simulation technique for craniospinal irradiation in supine position

International Nuclear Information System (INIS)

Lee, Suk; Kim, Yong Bae; Chu, Sung Sil; Suh, Chang Ok; Kwon, Soo Il

2002-01-01

In order to perform craniospinal irradiation (CSI) in the supine position on patients who are unable to lie in the prone position, a new simulation technique using a CT simulator was developed and its availability was evaluated. A CT simulator and a 3-D conformal treatment planning system were used to develop CSI in the supine position. The head and neck were immobilized with a thermoplastic mask in the supine position and the entire body was immobilized with a Vac-Loc. A volumetric image was then obtained using the CT simulator. In order to improve the reproducibility of the patients' setup, datum lines and points were marked on the head and the body. Virtual fluoroscopy was performed with the removal of visual obstacles such as the treatment table or the immobilization devices. After the virtual simulation, the treatment isocenters of each field were marked on the body and the immobilization devices at the conventional simulation room. Each treatment field was confirmed by comparing the fluoroscopy images with the digitally reconstructed radiography (DRR)/digitally composite radiography (DCR) images from the virtual simulation. The port verification films from the first treatment were also compared with the DRR/DCR images for a geometrical verification. CSI in the supine position was successfully performed in 9 patients. It required less than 20 minutes to construct the immobilization device and to obtain the whole body volumetric images. This made it possible to not only reduce the patients' inconvenience, but also to eliminate the position change variables during the long conventional simulation process. In addition, by obtaining the CT volumetric image, critical organs, such as the eyeballs and spinal cord, were better defined, and the accuracy of the port designs and shielding was improved. The difference between the DRRs and the portal films were less than 3 mm in the vertebral contour. CSI in the supine position is feasible in patients who cannot lie on

CT simulation technique for craniospinal irradiation in supine position

Energy Technology Data Exchange (ETDEWEB)

Lee, Suk; Kim, Yong Bae; Chu, Sung Sil; Suh, Chang Ok [Yonsei Cancer Center, College of Medicine, Yonsei University, Seoul (Korea, Republic of); Kwon, Soo Il [Kyonggi University, Seoul (Korea, Republic of)

2002-06-15

In order to perform craniospinal irradiation (CSI) in the supine position on patients who are unable to lie in the prone position, a new simulation technique using a CT simulator was developed and its availability was evaluated. A CT simulator and a 3-D conformal treatment planning system were used to develop CSI in the supine position. The head and neck were immobilized with a thermoplastic mask in the supine position and the entire body was immobilized with a Vac-Loc. A volumetric image was then obtained using the CT simulator. In order to improve the reproducibility of the patients' setup, datum lines and points were marked on the head and the body. Virtual fluoroscopy was performed with the removal of visual obstacles such as the treatment table or the immobilization devices. After the virtual simulation, the treatment isocenters of each field were marked on the body and the immobilization devices at the conventional simulation room. Each treatment field was confirmed by comparing the fluoroscopy images with the digitally reconstructed radiography (DRR)/digitally composite radiography (DCR) images from the virtual simulation. The port verification films from the first treatment were also compared with the DRR/DCR images for a geometrical verification. CSI in the supine position was successfully performed in 9 patients. It required less than 20 minutes to construct the immobilization device and to obtain the whole body volumetric images. This made it possible to not only reduce the patients' inconvenience, but also to eliminate the position change variables during the long conventional simulation process. In addition, by obtaining the CT volumetric image, critical organs, such as the eyeballs and spinal cord, were better defined, and the accuracy of the port designs and shielding was improved. The difference between the DRRs and the portal films were less than 3 mm in the vertebral contour. CSI in the supine position is feasible in patients who cannot

An indigenous economic technique of positive pressure retrograde urethrography in female patients

Directory of Open Access Journals (Sweden)

H Singh

2001-01-01

Full Text Available Usually double balloon catheter is required forpositive pressure retrograde urethrography in females. We describe a technique of positive pressure retrograde urethrography using Foley catheter and rubber stopper, inexpensive and could be adopted in any hospital or radiological suite.

A Reinforcement Learning Model Equipped with Sensors for Generating Perception Patterns: Implementation of a Simulated Air Navigation System Using ADS-B (Automatic Dependent Surveillance-Broadcast) Technology.

Science.gov (United States)

Álvarez de Toledo, Santiago; Anguera, Aurea; Barreiro, José M; Lara, Juan A; Lizcano, David

2017-01-19

Over the last few decades, a number of reinforcement learning techniques have emerged, and different reinforcement learning-based applications have proliferated. However, such techniques tend to specialize in a particular field. This is an obstacle to their generalization and extrapolation to other areas. Besides, neither the reward-punishment (r-p) learning process nor the convergence of results is fast and efficient enough. To address these obstacles, this research proposes a general reinforcement learning model. This model is independent of input and output types and based on general bioinspired principles that help to speed up the learning process. The model is composed of a perception module based on sensors whose specific perceptions are mapped as perception patterns. In this manner, similar perceptions (even if perceived at different positions in the environment) are accounted for by the same perception pattern. Additionally, the model includes a procedure that statistically associates perception-action pattern pairs depending on the positive or negative results output by executing the respective action in response to a particular perception during the learning process. To do this, the model is fitted with a mechanism that reacts positively or negatively to particular sensory stimuli in order to rate results. The model is supplemented by an action module that can be configured depending on the maneuverability of each specific agent. The model has been applied in the air navigation domain, a field with strong safety restrictions, which led us to implement a simulated system equipped with the proposed model. Accordingly, the perception sensors were based on Automatic Dependent Surveillance-Broadcast (ADS-B) technology, which is described in this paper. The results were quite satisfactory, and it outperformed traditional methods existing in the literature with respect to learning reliability and efficiency.

Management of Reinforcement Corrosion

DEFF Research Database (Denmark)

Küter, André; Geiker, Mette Rica; Møller, Per

Reinforcement corrosion is the most important cause for deterioration of reinforced concrete structures, both with regard to costs and consequences. Thermodynamically consistent descriptions of corrosion mechanisms are expected to allow the development of innovative concepts for the management...... of reinforcement corrosion....

Effect Of Age And Concrete Cover Thickness On Steel Reinforcement Corrosion At Splash Zone In Reinforced Concrete Hydraulic Structures

Directory of Open Access Journals (Sweden)

Nada M. Al- Galawi

2015-08-01

Full Text Available Corrosion of reinforcing steel bars in reinforced concrete is considered as one of the biggest problems that face countries overlooking to the Arabian Gulf including Iraq. The research aims to study the effect of the corrosion of steel bars in concrete structures that are exposed to wetting and drying via waves. Reinforced concrete samples were exposed to marine simulated environment for 90 days using prepared system for this purpose. At the end of exposure period polarization test was implemented to measure the actual corrosion rate in each sample. After that the corrosion process was accelerated using impressed current technique by applying a constant electric current DC to the reinforcing bars. Depending on the corrosion current in natural conditions which was measured in polarization test periods of exposing samples to accelerated corrosion current so as to maintain virtual exposure ages of 5 and 25 years of exposure to natural corrosion were calculated. The results showed a remarkable increase in the corrosion current of steel bars in samples that had lower concrete cover thickness. The increase in the cover thickness from 20mm to 40 and 65 mm had a significant effect on reducing the corrosion current at the age of 90 days to about 70 of its original value in both cases. At the virtual exposure age of 5 years the reduction percentage in the corrosion current resulted from increasing cover thickness from 20mm to 40 and 65 mm were 43 and 79 respectively.

Marketing Animal-Friendly Products: Addressing the Consumer Social Dilemma with Reinforcement Positioning Strategies

Science.gov (United States)

Ingenbleek, Paul T.M.; van Trijp, Hans C.M.; van der Veen, Gerrita

2017-01-01

Simple Summary Modern production systems aimed at improving animal welfare are more costly than traditional systems. Animal-friendly products are therefore typically more expensive than mainstream products, which presents one of the main barriers to consumer animal-friendly product choice. To overcome this barrier, marketing strategies that associate animal welfare with different types of value, such as taste, healthiness or good feeling, may be useful. This article presents a theoretical framework with marketing strategies using various types of value, suitable for animal-friendly products to encourage consumers to buy animal-friendly instead of mainstream products. We also explain why some consumers, such as those with a rational or an intuitive thinking style, may be more sensitive to some strategies over others, giving directions to marketing managers on how to approach different types of consumers. Because the credibility of animal welfare claims is a critical issue in marketing animal-friendly products, we address this issue as well. Specifically, we propose that, to gain consumer trust, companies selling animal-friendly products need to take into account the impact of their overall strategy on the effectiveness of marketing strategies for individual products and that they may need to collaborate with relevant stakeholders, such as media or animal-interest organizations. Abstract This article presents a conceptual framework that aims to encourage consumer animal-friendly product choice by introducing positioning strategies for animal-friendly products. These strategies reinforce the animal welfare with different types of consumption values and can therefore reduce consumers’ social dilemma, which is a major barrier to animal-friendly consumer choices. The article suggests how animal-friendly products can use various types of consumption values (functional, sensory, emotional, social, epistemic and situational) to create an attractive position relative to

Gaudi and reinforced concrete in construction

OpenAIRE

Grima Lopez, Rosa; Aguado de Cea, Antonio; Gómez Serrano, José

2013-01-01

The first two decades of the 20th century witnessed the introduction and expansion of reinforced concrete as a building material in Spain. Few years passed between the introduction of the first patents in the most industrialized areas of the Iberian Peninsula and the subsequent generalization of the technique through scientific knowledge obtained in universities. This period coincides almost completely with the professional career of Antoni Gaudí, one of the most famous Catalan architects. Th...

An exploration of antecedents of positive affect among the elderly: a cross-sectional study

Science.gov (United States)

2016-01-01

Abstract Background: Positive affect contributes to the healthy life style, which, in turn, explains life satisfaction and psychological well-being among the elderly. Existent literature has reinforced that physical activity participation influences development of positive affect for the elderly. Because of the increased life constraints and physical problems, however, maintenance of positive affect might be challenging for elderly people. Methods : Data were drawn from a sample of the Survey of Health, Ageing and Retirement in Europe. A total sample of 3845 males and 3912 females aged between 65 and 103 years from 16 European countries was analyzed. Perception of life constraints, health problems, physical activity engagement and positive affect were measured by a structured questionnaire. Confirmatory factor analysis and a technique of structural equation modelling were employed using Amos 18 to examine the hypothesized relationships between study variables. Results: Perceived life constraints and physical problems significantly affected the acquisition of positive affect among the elderly. Physical activity was found to have a significant path coefficient towards the measure of positive attitude and emotion. Physical activity was also a significant mediator between physical problems and positive affect. Conclusions: This study extended our understanding of how the perception of life constraints and health problems influence the elderly’s daily experience. Study finding reinforced the goodness of physical activity participation to enhance positive affect among the elderly. We should administer sustainable and evidence-based physical activity including interventions and infrastructure to improve positive affect and psychological well-bing among the elderly. PMID:25829500

An exploration of antecedents of positive affect among the elderly: a cross-sectional study.

Science.gov (United States)

Lee, Sunwoo

2016-02-01

Positive affect contributes to the healthy life style, which, in turn, explains life satisfaction and psychological well-being among the elderly. Existent literature has reinforced that physical activity participation influences development of positive affect for the elderly. Because of the increased life constraints and physical problems, however, maintenance of positive affect might be challenging for elderly people. Data were drawn from a sample of the Survey of Health, Ageing and Retirement in Europe. A total sample of 3845 males and 3912 females aged between 65 and 103 years from 16 European countries was analyzed. Perception of life constraints, health problems, physical activity engagement and positive affect were measured by a structured questionnaire. Confirmatory factor analysis and a technique of structural equation modelling were employed using Amos 18 to examine the hypothesized relationships between study variables. Perceived life constraints and physical problems significantly affected the acquisition of positive affect among the elderly. Physical activity was found to have a significant path coefficient towards the measure of positive attitude and emotion. Physical activity was also a significant mediator between physical problems and positive affect. This study extended our understanding of how the perception of life constraints and health problems influence the elderly's daily experience. Study finding reinforced the goodness of physical activity participation to enhance positive affect among the elderly. We should administer sustainable and evidence-based physical activity including interventions and infrastructure to improve positive affect and psychological well-bing among the elderly. © The Author 2015. Published by Oxford University Press on behalf of the European Public Health Association. All rights reserved.

Reinforcing and discriminative stimulus properties of music in goldfish.

Science.gov (United States)

Shinozuka, Kazutaka; Ono, Haruka; Watanabe, Shigeru

2013-10-01

This paper investigated whether music has reinforcing and discriminative stimulus properties in goldfish. Experiment 1 examined the discriminative stimulus properties of music. The subjects were successfully trained to discriminate between two pieces of music--Toccata and Fugue in D minor (BWV 565) by J. S. Bach and The Rite of Spring by I. Stravinsky. Experiment 2 examined the reinforcing properties of sounds, including BWV 565 and The Rite of Spring. We developed an apparatus for measuring spontaneous sound preference in goldfish. Music or noise stimuli were presented depending on the subject's position in the aquarium, and the time spent in each area was measured. The results indicated that the goldfish did not show consistent preferences for music, although they showed significant avoidance of noise stimuli. These results suggest that music has discriminative but not reinforcing stimulus properties in goldfish. Copyright © 2013 Elsevier B.V. All rights reserved.

Numerical Limit Analysis of Reinforced Concrete Structures

DEFF Research Database (Denmark)

Larsen, Kasper Paaske

For more than half a century, limit state analysis based on the extremum principles have been used to assess the load bearing capacity of reinforced concrete structures. Extensi- ve research within the field has lead to several techniques for performing such analysis manually. While these manual...... methods provide engineers with valuable tools for limit sta- te analysis, their application becomes difficult with increased structural complexity. The main challenge is to solve the optimization problem posed by the extremum principles. This thesis is a study of how numerical methods can be used to solve...... limit state analysis problems. The work focuses on determination of the load bearing capacity of reinforced concrete structures by employing the lower bound theorem and a finite element method using equilibrium elements is developed. The recent year’s development within the field of convex optimization...

Effects of carbon nanotube content and annealing temperature on the hardness of CNT reinforced aluminum nanocomposites processed by the high pressure torsion technique

Energy Technology Data Exchange (ETDEWEB)

Phuong, Doan Dinh, E-mail: phuongdd@ims.vast.ac.vn [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Str., Cau Giay Distr., Hanoi (Viet Nam); Trinh, Pham Van; An, Nguyen Van; Luan, Nguyen Van; Minh, Phan Ngoc [Institute of Materials Science, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet Str., Cau Giay Distr., Hanoi (Viet Nam); Khisamov, Rinat Kh.; Nazarov, Konstantin S.; Zubairov, Linar R.; Mulyukov, Radik R.; Nazarov, Ayrat A. [Institute for Metals Superplasticity Problems, Russian Academy of Sciences 39, Stepan Khalturin Str., Ufa 450001 (Russian Federation)

2014-11-15

Highlights: • CNT/Al nanocomposites were consolidated by HIP and subsequently processed by the high pressure torsion technique. • High pressure torsion processing was unable to break apart or disperse the CNT agglomerates persisted in powder preparation. • HPT-processed CNT/Al nanocomposites exhibited secondary hardening during annealing at temperatures below 150 °C. - Abstract: In this paper, the microstructure and hardness of CNT reinforced aluminium (CNT/Al) nanocomposites prepared by the advanced powder metallurgy method and subsequently processed by the high pressure torsion (HPT) technique are studied. The effects of CNT content and annealing temperature on the hardness of the nanocomposites are investigated. The results show that annealing materials at temperatures below 150 °C leads to secondary hardening, while annealing at higher temperatures soften the nanocomposites. HPT-processed CNT/Al nanocomposites with 1.5 wt.% of CNTs are shown to have the highest hardness in comparison with other composites containing CNTs from 0 up to 2 wt.%. Microstructures, CNT distribution and the phase composition of CNT/Al nanocomposites are investigated by transmission and scanning electron microscopy and X-ray diffraction techniques.

Application of micro blasting technique to demolition of biological shield wall of reactor building

International Nuclear Information System (INIS)

Kontani, Osamu

2016-01-01

Although heavily reinforced concrete structures in nuclear facilities could be dismantled effectively with the controlled blasting technique, the noises and vibrations caused by blasting were matters of concern. Recently, in the building replacement at urban areas, there are increasing cases of demolition of large reinforced concrete members below ground. Instead of applying heavy weight breakers, the micro blasting technique that enables to lower noises and vibrations has developed and applied to demolition work of large reinforced concrete members in urban areas. In this report, the features of the micro blasting technique is reviewed by comparing with existing controlled blasting technique and its applicability to demolition work of nuclear facilities is investigated. The results of those study find that it is confirmed that the micro blasting technique could be applicable to large reinforced concrete structures in nuclear facilities because of the low levels of noises and vibrations. However, it is recommended to perform mock-up tests to confirm the demolition efficiency and levels of the noises and vibrations since the rebar used in nuclear facilities is larger in diameters and in rebar ratio compared with ordinary reinforced concrete structures. (author)

Nano-Aramid Fiber Reinforced Polyurethane Foam

Science.gov (United States)

Semmes, Edmund B.; Frances, Arnold

2008-01-01

Closed cell polyurethane and, particularly, polyisocyanurate foams are a large family of flexible and rigid products the result of a reactive two part process wherein a urethane based polyol is combined with a foaming or "blowing" agent to create a cellular solid at room temperature. The ratio of reactive components, the constituency of the base materials, temperature, humidity, molding, pouring, spraying and many other processing techniques vary greatly. However, there is no known process for incorporating reinforcing fibers small enough to be integrally dispersed within the cell walls resulting in superior final products. The key differentiating aspect from the current state of art resides in the many processing technologies to be fully developed from the novel concept of milled nano pulp aramid fibers and their enabling entanglement capability fully enclosed within the cell walls of these closed cell urethane foams. The authors present the results of research and development of reinforced foam processing, equipment development, strength characteristics and the evolution of its many applications.

Positioning of the patient during shoulder surgery: an inexpensive, safe and easy technique.

Science.gov (United States)

Van Tongel, Alexander; Hardeman, François; Karelse, Anne; de Wilde, Lieven

2013-01-01

The knowledge of shoulder pathology has improved tremendously in the last decades, and shoulder surgery is increasingly performed because of new treatment options and better operative results. Nowadays most surgical shoulder procedures are performed in the sitting or semi-sitting (beach chair) position. Stability of the patient and the ability to flex, extend and rotate the shoulder during surgery are crucial to improve exposure of the surgical field and lower the risk of perioperative complications. We developed an easy, safe and inexpensive surgical set-up providing a very good posterior, superior and anterior access to the shoulder in the sitting or semi-sitting position. In this technique, the patient is placed supine with the head at the foot end of the table and the body positioned slightly eccentrically with the back being supported by the leg plate contralateral to the operative side, avoiding any contact with the scapula of the operative side. A neck support is attached on an extra bar at the contralateral side and accommodated to the patient's lordosis. Next, the leg plate on the operative side is removed, and the head and the body are secured to the table with adhesive dressing. This way a stable positioning of the patient is obtained during the whole procedure, and the shoulder girdle is completely free. The set-up can accommodate patients of different stature and weight without the need to adapt the technique. This position also gives the possibility to provide an excellent radiographic view of the shoulder during operative fracture treatment. Our technique further allows a significant reduction in costs. A surgical table, extra bar, additional arm support and neck support are usually available and can be used in different settings, without the need for a specific shoulder table.

Analysis of RDSS positioning accuracy based on RNSS wide area differential technique

Science.gov (United States)

Xing, Nan; Su, RanRan; Zhou, JianHua; Hu, XiaoGong; Gong, XiuQiang; Liu, Li; He, Feng; Guo, Rui; Ren, Hui; Hu, GuangMing; Zhang, Lei

2013-10-01

The BeiDou Navigation Satellite System (BDS) provides Radio Navigation Service System (RNSS) as well as Radio Determination Service System (RDSS). RDSS users can obtain positioning by responding the Master Control Center (MCC) inquiries to signal transmitted via GEO satellite transponder. The positioning result can be calculated with elevation constraint by MCC. The primary error sources affecting the RDSS positioning accuracy are the RDSS signal transceiver delay, atmospheric trans-mission delay and GEO satellite position error. During GEO orbit maneuver, poor orbit forecast accuracy significantly impacts RDSS services. A real-time 3-D orbital correction method based on wide-area differential technique is raised to correct the orbital error. Results from the observation shows that the method can successfully improve positioning precision during orbital maneuver, independent from the RDSS reference station. This improvement can reach 50% in maximum. Accurate calibration of the RDSS signal transceiver delay precision and digital elevation map may have a critical role in high precise RDSS positioning services.

Thermographic inspection of bond defects in Fiber Reinforced Polymer applied to masonry structures

Science.gov (United States)

Masini, N.; Aiello, M. A.; Capozzoli, L.; Vasanelli, E.

2012-04-01

Nowadays, externally bonded Fiber Reinforced Polymers (FRP) are extensively used for strengthening and repairing masonry and reinforced concrete existing structures; they have had a rapid spread in the area of rehabilitation for their many advantages over other conventional repair systems, such as lightweight, excellent corrosion and fatigue resistance, high strength, etc. FRP systems applied to masonry or concrete structures are typically installed using a wet-layup technique.The method is susceptible to cause flaws or defects in the bond between the FRP system and the substrate, which may reduce the effectiveness of the reinforcing systems and the correct transfer of load from the structure to the composite. Thus it is of primary importance to detect the presence of defects and to quantify their extension in order to eventually provide correct repair measurements. The IR thermography has been cited by the several guidelines as a good mean to qualitatively evaluate the presence of installation defects and to monitor the reinforcing system with time.The method is non-destructive and does not require contact with the composite or other means except air to detect the reinforcement. Some works in the literature have been published on this topic. Most of the researches aim at using the IR thermography technique to characterize quantitatively the defects in terms of depth, extension and type in order to have an experimental database on defect typology to evaluate the long term performances of the reinforcing system. Nevertheless, most of the works in the literature concerns with FRP applied to concrete structures without considering the case of masonry structures. In the present research artificial bond defects between FRP and the masonry substrate have been reproduced in laboratory and the IR multi temporal thermography technique has been used to detect them. Thermographic analysis has been carried out on two wall samples having limited dimensions (100 x 70 cm) both

Stress-Strain Relationship of Synthetic Fiber Reinforced Concrete Columns

Directory of Open Access Journals (Sweden)

Rosidawani

2017-01-01

Full Text Available Many empirical confinement models for normal and high strength concrete have been developed. Nevertheless, reported studies in the term of confinement of fiber reinforced concrete are limited. Whereas, the use of fiber reinforced concrete in structural elements has become the subject of the research and has indicated positive experiences. Since the stress-strain relationship of concrete in compression is required for analysis of structural members, the study of the stress-strain relationship for synthetic fiber reinforced concrete is substantial. The aim of the study is to examine the capabilities of the various models available in the literature to predict the actual experimental behavior of synthetic fiber reinforced high-strength concrete columns. The experimental data used are the results of the circular column specimens with the spiral spacing and the volume fraction of synthetic fiber as the test variables. The axial stress-strain curves from the tests are then compared with the various models of confinement from the literature. The performance index of each model is measured by using the coefficient of variation (COV concept of stress and strain behavior parameter. Among the confinement models, Cusson model shows the closest valid value of the coefficient of variation.

Influence of transverse reinforcement on perforation resistance of reinforced concrete slabs under hard missile impact

International Nuclear Information System (INIS)

Orbovic, Nebojsa; Sagals, Genadijs; Blahoianu, Andrei

2015-01-01

This paper describes the work conducted by the Canadian Nuclear Safety Commission (CNSC) related to the influence of transverse reinforcement on perforation capacity of reinforced concrete (RC) slabs under “hard” missile impact (impact with negligible missile deformations). The paper presents the results of three tests on reinforced concrete slabs conducted at VTT Technical Research Centre (Finland), along with the numerical simulations as well as a discussion of the current code provisions related to impactive loading. Transverse reinforcement is widely used for improving the shear and punching strength of concrete structures. However, the effect of this reinforcement on the perforation resistance under localized missile impact is still unclear. The goal of this paper is to fill the gap in the current literature related to this topic. Based on similar tests designed by the authors with missile velocity below perforation velocity, it was expected that transverse reinforcement would improve the perforation resistance. Three slabs were tested under almost identical conditions with the only difference being the transverse reinforcement. One slab was designed without transverse reinforcement, the second one with the transverse reinforcement in form of conventional stirrups with hooks and the third one with the transverse reinforcement in form of T-headed bars. Although the transverse reinforcement reduced the overall damage of the slabs (the rear face scabbing), the conclusion from the tests is that the transverse reinforcement does not have important influence on perforation capacity of concrete slabs under rigid missile impact. The slab with T-headed bars presented a slight improvement compared to the baseline specimen without transverse reinforcement. The slab with conventional stirrups presented slightly lower perforation capacity (higher residual missile velocity) than the slab without transverse reinforcement. In conclusion, the performed tests show slightly

Effect of nanocellulose isolation techniques on the formation of reinforced poly(vinyl alcohol nanocomposite films

Directory of Open Access Journals (Sweden)

H. Y. Zhan

2012-10-01

Full Text Available Three techniques including acid hydrolysis (AH, 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO-mediated oxidation (TMO and ultrasonication (US were introduced to isolate nanocellulose from microcrystalline cellulose, in order to reinforce poly(vinyl alcohol (PVA films. Important differences were noticed in fiber quality of nanocellulose and film properties of PVA nanocomposite films. The TMO treatment was more efficient in nanocellulose isolation with higher aspect ratio, surface charge (–47 mV and yields (37%. While AH treatment resulted in higher crystallinity index (88.1% and better size dispersion. The fracture surface, thermal behavior and mechanical properties of the PVA nanocomposite films were investigated by means of scanning electron microscopy (SEM, differential scanning calorimetry (DSC, thermogravimetric analysis (TGA and tensile testing. The results showed that both the TMO-derived and AH-derived nanocellulose could be dispersed homogeneously in the PVA matrices. AH/PVA films had higher elongation at break (51.59% at 6 wt% nanocellulose loading as compared with TMO/PVA, while TMO/PVA films shown superior tensile modulus and strength with increments of 21.5% and 10.2% at 6wt% nanocellulose loading. The thermal behavior of the PVA nanocomposite films was higher improved with TMO-derived nanofibrils addition.

Positive Contrast MRI Techniques for Visualization of Iron-Loaded Hernia Mesh Implants in Patients.

Directory of Open Access Journals (Sweden)

Alexander Ciritsis

Full Text Available In MRI, implants and devices can be delineated via susceptibility artefacts. To discriminate susceptibility voids from proton-free structures, different positive contrast techniques were implemented. The purpose of this study was to evaluate a pulse sequence-based positive contrast technique (PCSI and a post-processing susceptibility gradient mapping algorithm (SGM for visualization of iron loaded mesh implants in patients.Five patients with iron-loaded MR-visible inguinal hernia mesh implants were examined at 1.5 Tesla. A gradient echo sequence (GRE; parameters: TR: 8.3ms; TE: 4.3ms; NSA:2; FA:20°; FOV:350mm² and a PCSI sequence (parameters: TR: 25ms; TE: 4.6ms; NSA:4; FA:20°; FOV:350mm² with on-resonant proton suppression were performed. SGM maps were calculated using two algorithms. Image quality and mesh delineation were independently evaluated by three radiologists.On GRE, the iron-loaded meshes generated distinct susceptibility-induced signal voids. PCSI exhibited susceptibility differences including the meshes as hyperintense signals. SGM exhibited susceptibility differences with positive contrast. Visually, the different algorithms presented no significant differences. Overall, the diagnostic value was rated best in GRE whereas PCSI and SGM were barely "sufficient".Both "positive contrast" techniques depicted implanted meshes with hyperintense signal. SGM comes without additional acquisition time and can therefore be utilized in every patient.

Studies of wheel-running reinforcement: parameters of Herrnstein's (1970) response-strength equation vary with schedule order.

Science.gov (United States)

Belke, T W

2000-05-01

Six male Wistar rats were exposed to different orders of reinforcement schedules to investigate if estimates from Herrnstein's (1970) single-operant matching law equation would vary systematically with schedule order. Reinforcement schedules were arranged in orders of increasing and decreasing reinforcement rate. Subsequently, all rats were exposed to a single reinforcement schedule within a session to determine within-session changes in responding. For each condition, the operant was lever pressing and the reinforcing consequence was the opportunity to run for 15 s. Estimates of k and R(O) were higher when reinforcement schedules were arranged in order of increasing reinforcement rate. Within a session on a single reinforcement schedule, response rates increased between the beginning and the end of a session. A positive correlation between the difference in parameters between schedule orders and the difference in response rates within a session suggests that the within-session change in response rates may be related to the difference in the asymptotes. These results call into question the validity of parameter estimates from Herrnstein's (1970) equation when reinforcer efficacy changes within a session.

Breast radiotherapy in the lateral decubitus position: A technique to prevent lung and heart irradiation

International Nuclear Information System (INIS)

Campana, Francois; Kirova, Youlia M.; Rosenwald, Jean-Claude; Dendale, Remi; Vilcoq, Jacques R.; Dreyfus, Helene; Fourquet, Alain

2005-01-01

Purpose: To present an original technique for breast radiotherapy, with the aim of limiting lung and heart irradiation, satisfying quality assurance criteria. Methods and Material: An original radiotherapy technique for breast irradiation has been developed at the Institute Curie in January 1996. It consists of isocentric breast irradiation in the lateral decubitus position (isocentric lateral decubitus [ILD]). This technique is indicated for voluminous or pendulous breasts needing breast irradiation only. Thin carbon fiber supports and special patient positioning devices have been developed especially for this technique. In vivo measurements were performed to check the dose distribution before the routine use of the technique. Results: ILD has been successfully implemented in routine practice, and 500 patients have been already treated. Breast radiotherapy is performed using a dose of 50 Gy at ICRU point in 25 fractions. ILD shows good homogeneity of the dose in breast treatment volume, treatment fields are perpendicular to the skin ensuring its protection, and extremely low dose is delivered to the underlying lung and heart. Conclusion: In cases of voluminous breasts or patients with a history of lung and heart disease, our technique provides several advantages over the conventional technique with opposing tangential fields. This technique improves the dose homogeneity according to the ICRU recommendations

Finite element modelling of concrete beams reinforced with hybrid fiber reinforced bars

Science.gov (United States)

Smring, Santa binti; Salleh, Norhafizah; Hamid, NoorAzlina Abdul; Majid, Masni A.

2017-11-01

Concrete is a heterogeneous composite material made up of cement, sand, coarse aggregate and water mixed in a desired proportion to obtain the required strength. Plain concrete does not with stand tension as compared to compression. In order to compensate this drawback steel reinforcement are provided in concrete. Now a day, for improving the properties of concrete and also to take up tension combination of steel and glass fibre-reinforced polymer (GFRP) bars promises favourable strength, serviceability, and durability. To verify its promise and support design concrete structures with hybrid type of reinforcement, this study have investigated the load-deflection behaviour of concrete beams reinforced with hybrid GFRP and steel bars by using ATENA software. Fourteen beams, including six control beams reinforced with only steel or only GFRP bars, were analysed. The ratio and the ordinate of GFRP to steel were the main parameters investigated. The behaviour of these beams was investigated via the load-deflection characteristics, cracking behaviour and mode of failure. Hybrid GFRP-Steel reinforced concrete beam showed the improvement in both ultimate capacity and deflection concomitant to the steel reinforced concrete beam. On the other hand, finite element (FE) modelling which is ATENA were validated with previous experiment and promising the good result to be used for further analyses and development in the field of present study.

Preparation of Ti-aluminide reinforced in situ aluminium matrix composites by reactive hot pressing

International Nuclear Information System (INIS)

Roy, D.; Ghosh, S.; Basumallick, A.; Basu, B.

2007-01-01

Aluminium based metal matrix composites reinforced with in situ Ti-aluminide and alumina particles were prepared by reactive hot pressing a powder mix of aluminium and nanosized TiO 2 powders. The reinforcements were formed in situ by exothermal reaction between the TiO 2 nano crystalline powder and aluminium. The thermal characteristics of the in situ reaction were studied with the aid of Differential scanning calorimetry (DSC). X-ray diffraction (XRD), Energy dispersive spectroscopy (EDS) and Scanning electron microscopy (SEM) techniques were employed to study the microstructural architecture of the composites as a function of hot pressing temperature and volume percent reinforcement. Microhardness measurements on the as prepared in situ aluminium matrix composites exhibit significant increase in hardness with increase in hot pressing temperature and volume fraction of reinforcement

Development of textile-reinforced carbon fibre aluminium composites manufactured with gas pressure infiltration methods

OpenAIRE

W. Hufenbach; M. Gude; A. Czulak; J. Śleziona; A. Dolata-Grosz; M. Dyzia

2009-01-01

Purpose: The aim of his paper is to show potential of textile-reinforced carbon fibre aluminium composite with advantage of the lightweight construction of structural components subjected to thermo-mechanical stress.Design/methodology/approach: The manufacture of specimens of the carbon fibre-reinforced aluminium was realised with the aid of an advanced differential gas pressure infiltration technique, which was developed at ILK, TU Dresden.Findings: The gas pressure infiltration technology e...

Fabrication and mechanical properties of self-reinforced poly(ethylene terephthalate composites

Directory of Open Access Journals (Sweden)

2011-03-01

Full Text Available Self-reinforced poly(ethylene terephthalate (PET composites prepared by using a modified film-stacking technique were examined in this study. The starting materials included a high tenacity PET yarn (reinforcement and a low melting temperature biodegradable polyester resin (matrix, both of which differ in their melting temperatures with a value of 56°C. This experiment produced composite sheets at three consolidation temperatures (Tc: 215, 225, and 235°C at a constant holding time (th: 6.5 min, and three holding times (3, 6.5 and 10 min at a constant consolidation temperature of 225°C. This study observed a significant improvement in the mechanical properties obtained in self-reinforced PET composites compared to the pure polyester resin. The results of tensile, flexural, and Izod impact tests proved that optimal conditions are low consolidation temperature and short holding time. The absorbed impact energy of the best self-reinforced PET composite material was 854.0 J/m, which is 63 times that of pure polyester resin.

Tensile Mechanical Property of Oil Palm Empty Fruit Bunch Fiber Reinforced Epoxy Composites

Science.gov (United States)

Ghazilan, A. L. Ahmad; Mokhtar, H.; Shaik Dawood, M. S. I.; Aminanda, Y.; Ali, J. S. Mohamed

2017-03-01

Natural, short, untreated and randomly oriented oil palm empty fruit bunch fiber reinforced epoxy composites were manufactured using vacuum bagging technique with 20% fiber volume composition. The performance of the composite was evaluated as an alternative to synthetic or conventional reinforced composites. Tensile properties such as tensile strength, modulus of elasticity and Poisson’s ratio were compared to the tensile properties of pure epoxy obtained via tensile tests as per ASTM D 638 specifications using Universal Testing Machine INSTRON 5582. The tensile properties of oil palm empty fruit bunch fiber reinforced epoxy composites were lower compared to plain epoxy structure with the decrement in performances of 38% for modulus of elasticity and 61% for tensile strength.

Applying reinforcement learning to the weapon assignment problem in air defence

CSIR Research Space (South Africa)

Mouton, H

2011-12-01

Full Text Available . The techniques investigated in this article were two methods from the machine-learning subfield of reinforcement learning (RL), namely a Monte Carlo (MC) control algorithm with exploring starts (MCES), and an off-policy temporal-difference (TD) learning...

Potential of Carbon Nanotube Reinforced Cement Composites as Concrete Repair Material

Directory of Open Access Journals (Sweden)

Tanvir Manzur

2016-01-01

Full Text Available Carbon nanotubes (CNTs are a virtually ideal reinforcing agent due to extremely high aspect ratios and ultra high strengths. It is evident from contemporary research that utilization of CNT in producing new cement-based composite materials has a great potential. Consequently, possible practical application of CNT reinforced cementitious composites has immense prospect in the field of applied nanotechnology within construction industry. Several repair, retrofit, and strengthening techniques are currently available to enhance the integrity and durability of concrete structures with cracks and spalling, but applicability and/or reliability is/are often limited. Therefore, there is always a need for innovative high performing concrete repair materials with good mechanical, rheological, and durability properties. Considering the mechanical properties of carbon nanotubes (CNTs and the test results of CNT reinforced cement composites, it is apparent that such composites could be used conveniently as concrete repair material. With this end in view, the applicability of multiwalled carbon nanotube (MWNT reinforced cement composites as concrete repair material has been evaluated in this study in terms of setting time, bleeding, and bonding strength (slant shear tests. It has been found that MWNT reinforced cement mortar has good prospective as concrete repair material since such composites exhibited desirable behavior in setting time, bleeding, and slant shear.

Influence of fibre orientation on the performance of steel fibre-reinforced concrete

OpenAIRE

Grünewald, Steffen; Laranjeira de Oliveira, Filipe; Walraven, Joost; Aguado de Cea, Antonio; Molins i Borrell, Climent

2012-01-01

The performance of fibre-reinforced materials in the hardened state depends on the material behaviour, the production method and influences related to the structure. The position and the orientation of fibres in a structure can differ from the homogenous distribution and the random orientation in a mixer. Due to the flow of the concrete, fibres are able to orient which makes the prediction of the structural behaviour of fibre-reinforced concrete more complex, but it also offers the potential ...

Experiments with Online Reinforcement Learning in Real-Time Strategy Games

DEFF Research Database (Denmark)

Toftgaard Andersen, Kresten; Zeng, Yifeng; Dahl Christensen, Dennis

2009-01-01

Real-time strategy (RTS) games provide a challenging platform to implement online reinforcement learning (RL) techniques in a real application. Computer, as one game player, monitors opponents' (human or other computers) strategies and then updates its own policy using RL methods. In this article......, we first examine the suitability of applying the online RL in various computer games. Reinforcement learning application depends on both RL complexity and the game features. We then propose a multi-layer framework for implementing online RL in an RTS game. The framework significantly reduces RL...... the effectiveness of our proposed framework and shed light on relevant issues in using online RL in RTS games....

Computational modelling of fibre-reinforced cementitious composites : An analysis of discrete and mesh-independent techniques

NARCIS (Netherlands)

Radtke, F.K.F.

2012-01-01

Failure patterns and mechanical behaviour of high performance fibre-reinforced cementitious composites depend to a large extent on the distribution of fibres within a specimen. A discrete treatment of fibres enables us to study the influence of various fibre distributions on the mechanical

Technology and Development of Self-Reinforced Polymer Composites

Science.gov (United States)

Alcock, Ben; Peijs, Ton

In recent years there has been an increasing amount of interest, both commercially and scientifically, in the emerging field of "self-reinforced polymer composites". These materials, which are sometimes also referred to as "single polymer composites", or "all-polymer composites", were first conceived in the 1970s, and are now beginning to appear in a range of commercial products. While high mechanical performance polymer fibres or tapes are an obvious precursor for composite development, various different technologies have been developed to consolidate these into two- or three-dimensional structures. This paper presents a review of the various processing techniques that have been reported in the literature for the manufacture of self-reinforced polymer composites from fibres or tapes of different polymers, and so exploit the fibre or tape performance in a commercial material or product.

Methods for producing reinforced carbon nanotubes

Science.gov (United States)

Ren, Zhifen [Newton, MA; Wen, Jian Guo [Newton, MA; Lao, Jing Y [Chestnut Hill, MA; Li, Wenzhi [Brookline, MA

2008-10-28

Methods for producing reinforced carbon nanotubes having a plurality of microparticulate carbide or oxide materials formed substantially on the surface of such reinforced carbon nanotubes composite materials are disclosed. In particular, the present invention provides reinforced carbon nanotubes (CNTs) having a plurality of boron carbide nanolumps formed substantially on a surface of the reinforced CNTs that provide a reinforcing effect on CNTs, enabling their use as effective reinforcing fillers for matrix materials to give high-strength composites. The present invention also provides methods for producing such carbide reinforced CNTs.

Monitoring device for reinforced concrete

International Nuclear Information System (INIS)

Matsuzaki, Tetsuo; Saito, Koichi; Furukawa, Hideyasu.

1994-01-01

A reactor container made of reinforced concretes is monitored for the temperature at each of portions upon placing concretes under construction of a plant, upon pressure-proof test and during plant operation. That is, optical fibers are uniformly laid spirally throughout the inside of the concretes. Pulses are injected from one end of the optical fibers, and the temperature at a reflection point can be measured by measuring specific rays (Raman scattering rays) among lights reflected after a predetermined period of time. According to the present invention, measurement for an optional position within a range where one fiber cable is laid can be conducted. Accordingly, it is possible to conduct temperature control upon concrete placing and apply temperature compensation for the measurement for stresses of the concretes and the reinforcing steels upon container pressure-proof. Further, during plant operation, if the temperature of the concretes rises due to thermal conduction of the temperature in the container, integrity of the concretes can be ensured by a countermeasures such as air conditioning. (I.S.)

Proposed satellite position determination systems and techniques for Geostationary Synthetic Aperture Radar

OpenAIRE

Martin Fuster, Roger; Fernández Usón, Marc; Casado Blanco, David; Broquetas Ibars, Antoni

2016-01-01

This paper proposes two different calibration techniques for Geostationary Synthetic Aperture Radar (GEOSAR) missions requiring a high precision positioning, based on Active Radar Calibrators and Ground Based Interferometry. The research is enclosed in the preparation studies of a future GEOSAR mission providing continuous monitoring at continental scale. Peer Reviewed

Satellite and terrestrial radio positioning techniques a signal processing perspective

CERN Document Server

Dardari, Davide; Falletti, Emanuela

2014-01-01

* The first book to combine satellite and terrestrial positioning techniques - vital for the understanding and development of new technologies * Written and edited by leading experts in the field, with contributors belonging to the European Commission's FP7 Network of Excellence NEWCOM++ Applications to a wide range of fields, including sensor networks, emergency services, military use, location-based billing, location-based advertising, intelligent transportation, and leisure Location-aware personal devices and location-based services have become ever more prominent in the past few years

Carbon Fiber Reinforced Polymer Grids for Shear and End Zone Reinforcement in Bridge Beams

Science.gov (United States)

2018-01-01

Corrosion of reinforcing steel reduces life spans of bridges throughout the United States; therefore, using non-corroding carbon fiber reinforced polymer (CFRP) reinforcement is seen as a way to increase service life. The use of CFRP as the flexural ...

Use of Fiber-Reinforced Cements in Masonry Construction and Structural Rehabilitation

Directory of Open Access Journals (Sweden)

Ece Erdogmus

2015-02-01

Full Text Available The use of fiber reinforcement in traditional concrete mixes has been extensively studied and has been slowly finding its regular use in practice. In contrast, opportunities for the use of fibers in masonry applications and structural rehabilitation projects (masonry and concrete structures have not been as deeply investigated, where the base matrix may be a weaker cementitious mixture. This paper will summarize the findings of the author’s research over the past 10 years in these particular applications of fiber reinforced cements (FRC. For masonry, considering both mortar and mortar-unit bond characteristics, a 0.5% volume fraction of micro fibers in type N Portland cement lime mortar appear to be a viable recipe for most masonry joint applications both for clay and concrete units. In general, clay units perform better with high water content fiber reinforced mortar (FRM while concrete masonry units (CMUs perform better with drier mixtures, so 130% and 110% flow rates should be targeted, respectively. For earth block masonry applications, fibers’ benefits are observed in improving local damage and water pressure resistance. The FRC retrofit technique proposed for the rehabilitation of reinforced concrete two-way slabs has exceeded expectations in terms of capacity increase for a relatively low cost in comparison to the common but expensive fiber reinforced polymer applications. For all of these applications of fiber-reinforced cements, further research with larger data pools would lead to further optimization of fiber type, size, and amount.

The potential of dielectric analysis as an on-line cure monitoring technique in the manufacture of advanced fibre reinforced composites

International Nuclear Information System (INIS)

McIlhagger, A.T.

2002-02-01

Composite manufacturing processes such as RTM, are being developed in the aerospace industry in order to promote and reduce the cost of advanced fibre reinforced composites. The aerospace industry has identified the need for a cure monitoring system to be utilised in this production, to improve the efficiency and reliability of processing. The system must be able to determine through-thickness properties of the composite, on-line and without affecting the integrity of the finished component. Literature has shown that a number of techniques are available but these do not address all of the requirements of industry. The most important process parameters in RTM are the resin flow, point of minimum viscosity, gelation and subsequent completion of cure. These 'key cure parameters' are often difficult to control accurately in the manufacturing environment. Although dielectric analysis has been around for many years, literature identified an urgent requirement for research on the interpretation of dielectric sensor data relating to these main process parameters. A dielectric laboratory instrument, operated in the parallel plate sensor configuration was utilised to simulate a standard RTM cure cycle. The important transitions in the resin, namely minimum viscosity, gelation, vitrification and completion of cure, were identified. The parallel plate dielectric technique was applied to composites containing conductive and non-conductive reinforcement fibres. The appropriate dielectric signals and frequency were determined based on the sensor configuration, insulating layer and resin/fabric type. Correlations have been demonstrated between dielectric results and other established thermal (DSC and. DMA) and mechanical test techniques (tensile, flexural and interlaminar shear). Test methods were designed and investigated to provide information to compare with dielectric data. The parallel plate configuration was used to investigate the effect of composite thickness variation on

Mechanical improvement of metal reinforcement rings for a finite ring-shaped superconducting bulk

Science.gov (United States)

Huang, Chen-Guang; Zhou, You-He

2018-03-01

As a key technique, reinforcement of type-II superconducting bulks with metal rings can efficiently improve their mechanical properties to enhance the maximum trapped field. In this paper, we study the magnetostrictive and fracture behaviors of a finite superconducting ring bulk reinforced by three typical reinforcing structures composed of metal rings during the magnetizing process by means of the minimization of magnetic energy and the finite element method. After a field-dependent critical current density is adopted, the magnetostriction, pinning-induced stress, and crack tip stress intensity factor are calculated considering the demagnetization effects. The results show that the mechanical properties of the ring bulk are strongly dependent on the reinforcing structure and the material and geometrical parameters of the metal rings. Introducing the metal ring can significantly reduce the hoop stress, and the reduction effect by internal reinforcement is much improved relative to external reinforcement. By comparison, bilateral reinforcement seems to be the best candidate structure. Only when the metal rings have particular Young's modulus and radial thickness will they contribute to improve the mechanical properties the most. In addition, if an edge crack is pre-existing in the ring bulk, the presence of metal rings can effectively avoid crack propagation since it reduces the crack tip stress intensity factor by nearly one order of magnitude.

Radiographic evaluation of coxofemoral joint laxity in dogs part I: New stress-radiographic positioning techniques

International Nuclear Information System (INIS)

Phiwipha Kamonrat; Duangdaun Kaenkangploo

2002-01-01

Two new stress-radiographic positioning techniques, namely 60 deg and 90 deg stress techniques, were introduced for quantifying hip joint laxity in dogs. The comparative characteristics and efficiency of these new techniques with angled hindlimbs were evaluated relative to the standard hip-extended radiographic technique. Forty, healthy, mongrel dogs with normal hip joint conformation were anesthetized and placed in dorsal recumbency before 3 radiograhps of the standard, 60 deg , and 90 deg stress techniques were taken. For the 60 deg stress technique, hindlimbs were extended in parallel to each other at 60 deg angled to the table top and stifles were slightly rotated inward, femoral heads were manually pushed in a craniodorsal direction during exposure. For the 90 deg stress technique, femurs were positioned perpendicular to the table top, stifles were 90 deg flexed and adducted and femoral heads were manually pushed in a craniodorsal direction during exposure. The subluxation index (SI) and dorsolateral subluxation score (DLS score) were calculated from 3 radiographic views for both hip joints to quantitate the relative degree of joint laxity. Results of the study indicated that the 60 deg (SI = 0.20+-0.045, DLS score = 62.5+-7.96 percent) and 90 deg (SI = 0.23+-0.044, DLS score = 61.2+-9.47 percent) stress-radiographs yielded significantly (p0.001) higher degree of hip joint laxity than the standard technique (SI)

The construction features of the deformation and force model of concrete and reinforced concrete resistance

Directory of Open Access Journals (Sweden)

Romashko Vasyl

2017-01-01

Full Text Available The main features of the deformation and force model of deformation of reinforced concrete elements and structures based on generalized diagrams of their state are considered in the article. Particular attention is focused on the basic methodological problems and shortcomings of modern "deformation" models. It is shown that in the most cases these problems can be solved by the generalized diagrams of reinforced concrete elements and structures real state. Thanks to these diagrams, the developed method: provides a single methodological approach to the calculation of reinforced concrete elements and structures normal sections for limit states; allows to reveal the internal static indeterminacy of heterogeneously deformable elements and structures in their ultimate limit state calculation; justifies the application of the basic and derived criteria of reinforced concrete elements and structures bearing capacity exhaustion; retains the essence of the physical processes of concrete and reinforced concrete structures deformation. The defining positions of the generalized (universal methodology for calculating reinforced concrete elements and structures are stated.

Adaptive Load Balancing of Parallel Applications with Multi-Agent Reinforcement Learning on Heterogeneous Systems

Directory of Open Access Journals (Sweden)

Johan Parent

2004-01-01

Full Text Available We report on the improvements that can be achieved by applying machine learning techniques, in particular reinforcement learning, for the dynamic load balancing of parallel applications. The applications being considered in this paper are coarse grain data intensive applications. Such applications put high pressure on the interconnect of the hardware. Synchronization and load balancing in complex, heterogeneous networks need fast, flexible, adaptive load balancing algorithms. Viewing a parallel application as a one-state coordination game in the framework of multi-agent reinforcement learning, and by using a recently introduced multi-agent exploration technique, we are able to improve upon the classic job farming approach. The improvements are achieved with limited computation and communication overhead.

High and low temperatures have unequal reinforcing properties in Drosophila spatial learning.

Science.gov (United States)

Zars, Melissa; Zars, Troy

2006-07-01

Small insects regulate their body temperature solely through behavior. Thus, sensing environmental temperature and implementing an appropriate behavioral strategy can be critical for survival. The fly Drosophila melanogaster prefers 24 degrees C, avoiding higher and lower temperatures when tested on a temperature gradient. Furthermore, temperatures above 24 degrees C have negative reinforcing properties. In contrast, we found that flies have a preference in operant learning experiments for a low-temperature-associated position rather than the 24 degrees C alternative in the heat-box. Two additional differences between high- and low-temperature reinforcement, i.e., temperatures above and below 24 degrees C, were found. Temperatures equally above and below 24 degrees C did not reinforce equally and only high temperatures supported increased memory performance with reversal conditioning. Finally, low- and high-temperature reinforced memories are similarly sensitive to two genetic mutations. Together these results indicate the qualitative meaning of temperatures below 24 degrees C depends on the dynamics of the temperatures encountered and that the reinforcing effects of these temperatures depend on at least some common genetic components. Conceptualizing these results using the Wolf-Heisenberg model of operant conditioning, we propose the maximum difference in experienced temperatures determines the magnitude of the reinforcement input to a conditioning circuit.

Earthquake behavior of steel cushion-implemented reinforced concrete frames

Science.gov (United States)

Özkaynak, Hasan

2018-04-01

The earthquake performance of vulnerable structures can be increased by the implementation of supplementary energy-dissipative metallic elements. The main aim of this paper is to describe the earthquake behavior of steel cushion-implemented reinforced concrete frames (SCI-RCFR) in terms of displacement demands and energy components. Several quasi-static experiments were performed on steel cushions (SC) installed in reinforced concrete (RC) frames. The test results served as the basis of the analytical models of SCs and a bare reinforced concrete frame (B-RCFR). These models were integrated in order to obtain the resulting analytical model of the SCI-RCFR. Nonlinear-time history analyses (NTHA) were performed on the SCI-RCFR under the effects of the selected earthquake data set. According to the NTHA, SC application is an effective technique for increasing the seismic performance of RC structures. The main portion of the earthquake input energy was dissipated through SCs. SCs succeeded in decreasing the plastic energy demand on structural elements by almost 50% at distinct drift levels.

Predictable Technique to Register Retruded Contact Position (RCP) Using a Disposable Jaw Relation Recording Device.

Science.gov (United States)

Daher, Tony; Lobel, William A; Massad, Joseph; Ahuja, Swati; Danilov, Zarko Jack

2015-05-01

The dental literature presents various definitions and techniques to describe and register centric relation (CR) or centric occlusion (CO). Briefly reviewing the literature in relation to CR, this article proposes the use of the term retruded contact position (RCP), clinically defined as retruded, unstrained, repeatable position and where the mandibular movements start when a Gothic arch tracing is used. With this clinical definition, a technique can be easily selected that meets all the requirements of such position. The article discusses the use of a jaw recorder that is an intraorally graphic recording device that results in a tracing of mandibular movements in one plane, with the apex of the tracing indicating the retruded, unstrained, and repeatable relationship. The intersection of the arcs produced by the right and left working movement form the apex of the Gothic arch tracing. Several clinical situations using the jaw recorder are described. Clinicians can now quickly and accurately record RCP, balance complete, partial, or implant dentures, and orthopedically reposition the mandible. The technique achieves highly reliable and reproducible results.

Study of flax hybrid preforms reinforced epoxy composites

International Nuclear Information System (INIS)

Muralidhar, B. A

2013-01-01

Highlights: • We examine the thermal, viscoelastic and mechanical behaviour of flax preform hybrid composites. • The thermal stability of the matrix decrease with increasing volume fraction of flax preforms. • The effect of number of preform layers and the lay-up architecture were studied.. • Morphological study on the fractured surface of the composite laminate is carried out. - Abstracts: This study investigates the thermal, mechanical and thermomechanical properties of flax hybrid preform reinforced epoxy composites. Flax plain weave fabric and 1 × 1 weft rib knitted structures were together used as reinforcements and the composites were produced using hand lay-up technique. Specimen preparation and testing were carried out as per ASTM standards. Thermogravimetric analysis (TGA) indicates a decrease in thermal stability of the matrix polymer with the incorporation of flax hybrid preform. The dynamic mechanical analysis revealed a shift in the T g with the addition of flax hybrid preforms. Mechanical data obtained showed that tensile strength and stiffness is a product of the fibre/matrix synergy, whereas the compressive strength and stiffness are contributed by the reinforcing matrix. Additionally, investigation show that laminate with knitted preform as skin layer exhibits superior mechanical properties. However, improved tensile properties at lower fibre volume fraction, reinforces the opinion that hybrid preform composites can offer significant benefits in terms of performance, weight and overall cost. The failure mechanism was analysed, by scanning electron microscope (SEM)

Motion sickness: a negative reinforcement model.

Science.gov (United States)

Bowins, Brad

2010-01-15

Theories pertaining to the "why" of motion sickness are in short supply relative to those detailing the "how." Considering the profoundly disturbing and dysfunctional symptoms of motion sickness, it is difficult to conceive of why this condition is so strongly biologically based in humans and most other mammalian and primate species. It is posited that motion sickness evolved as a potent negative reinforcement system designed to terminate motion involving sensory conflict or postural instability. During our evolution and that of many other species, motion of this type would have impaired evolutionary fitness via injury and/or signaling weakness and vulnerability to predators. The symptoms of motion sickness strongly motivate the individual to terminate the offending motion by early avoidance, cessation of movement, or removal of oneself from the source. The motion sickness negative reinforcement mechanism functions much like pain to strongly motivate evolutionary fitness preserving behavior. Alternative why theories focusing on the elimination of neurotoxins and the discouragement of motion programs yielding vestibular conflict suffer from several problems, foremost that neither can account for the rarity of motion sickness in infants and toddlers. The negative reinforcement model proposed here readily accounts for the absence of motion sickness in infants and toddlers, in that providing strong motivation to terminate aberrant motion does not make sense until a child is old enough to act on this motivation.

Influence of Steel Reinforcement on In-Situ Stress Evaluation in Concrete Structures by the Core-Drilling Method

International Nuclear Information System (INIS)

McGinnis, M. J.; Pessiki, S.

2006-01-01

The core-drilling method is an emerging technique for evaluating in-situ stress in a concrete structure. A small hole is drilled into the structure, and the deformations in the vicinity of the hole are measured and related via elasticity theory to the stress. The method is similar to the ASTM hole-drilling strain-gauge method excepting that displacements rather than strains are the measured quantities. The technique may be considered nondestructive since the ability of the structure to perform its function is unaffected, and the hole is easily repaired. Displacement measurements in the current work are performed using 3D digital image correlation and industrial photogrammetry. The current paper addresses perturbations in the method caused by steel reinforcement within the concrete. The reinforcement is significantly stiffer than the surrounding concrete, altering the expected displacement field. A numerical investigation performed indicates an under-prediction of stress by as much as 18 percent in a heavily reinforced structure, although the effect is significantly smaller for more common amounts of reinforcement

Influence of Steel Reinforcement on In-Situ Stress Evaluation in Concrete Structures by the Core-Drilling Method

Science.gov (United States)

McGinnis, M. J.; Pessiki, S.

2006-03-01

The core-drilling method is an emerging technique for evaluating in-situ stress in a concrete structure. A small hole is drilled into the structure, and the deformations in the vicinity of the hole are measured and related via elasticity theory to the stress. The method is similar to the ASTM hole-drilling strain-gauge method excepting that displacements rather than strains are the measured quantities. The technique may be considered nondestructive since the ability of the structure to perform its function is unaffected, and the hole is easily repaired. Displacement measurements in the current work are performed using 3D digital image correlation and industrial photogrammetry. The current paper addresses perturbations in the method caused by steel reinforcement within the concrete. The reinforcement is significantly stiffer than the surrounding concrete, altering the expected displacement field. A numerical investigation performed indicates an under-prediction of stress by as much as 18 percent in a heavily reinforced structure, although the effect is significantly smaller for more common amounts of reinforcement.

Combining noncontingent reinforcement and differential reinforcement schedules as treatment for aberrant behavior.

OpenAIRE

Marcus, B A; Vollmer, T R

1996-01-01

Research has shown that noncontingent reinforcement (NCR) can be an effective behavior-reduction procedure when based on a functional analysis. The effects of NCR may be a result of elimination of the contingency between aberrant behavior and reinforcing consequences (extinction) or frequent and free access to reinforcers that may reduce the participant's motivation to engage in aberrant behaviors or mands. If motivation is momentarily reduced, behavior such as mands may not be sensitive to p...

Operant Reinforcement with Structural Family Therapy in Treating Anorexia Nervosa

Science.gov (United States)

Perlman, Lawrence M.; Bender, Sheila S.

1975-01-01

The authors successfully treated two families in which the index patients were anorectic adolescent girls by combining structural family therapy with behavioral modification techniques. Phases which appear to be typical of the treatment are described. A discussion of the value of the operant reinforcement procedure in family therapy follows.…

A novel technique of anesthesia induction in supine position with impaled knife in the back

Directory of Open Access Journals (Sweden)

Ajay Kumar

2015-01-01

Full Text Available Current technique of airway management for impaled knife in the back includes putting the patient in lateral position and intubation. We present here a novel technique of anesthesia induction (intubation and central line insertion in a patient with impaled knife in the back which is simple and easily reproducible. This technique can be used for single lung ventilation using double lumen tube or bronchial blocker also if desired.

Degradation of Waterfront Reinforced Concrete Structures

African Journals Online (AJOL)

Key words: Degradation, reinforced concrete, Dar es Salaam port. Abstract—One of the ... especially corrosion of the reinforcement. ... Corrosion of steel reinforcement contributes .... cracks along the line of reinforcement bars and most of the ...

Learning alternative movement coordination patterns using reinforcement feedback.

Science.gov (United States)

Lin, Tzu-Hsiang; Denomme, Amber; Ranganathan, Rajiv

2018-05-01

One of the characteristic features of the human motor system is redundancy-i.e., the ability to achieve a given task outcome using multiple coordination patterns. However, once participants settle on using a specific coordination pattern, the process of learning to use a new alternative coordination pattern to perform the same task is still poorly understood. Here, using two experiments, we examined this process of how participants shift from one coordination pattern to another using different reinforcement schedules. Participants performed a virtual reaching task, where they moved a cursor to different targets positioned on the screen. Our goal was to make participants use a coordination pattern with greater trunk motion, and to this end, we provided reinforcement by making the cursor disappear if the trunk motion during the reach did not cross a specified threshold value. In Experiment 1, we compared two reinforcement schedules in two groups of participants-an abrupt group, where the threshold was introduced immediately at the beginning of practice; and a gradual group, where the threshold was introduced gradually with practice. Results showed that both abrupt and gradual groups were effective in shifting their coordination patterns to involve greater trunk motion, but the abrupt group showed greater retention when the reinforcement was removed. In Experiment 2, we examined the basis of this advantage in the abrupt group using two additional control groups. Results showed that the advantage of the abrupt group was because of a greater number of practice trials with the desired coordination pattern. Overall, these results show that reinforcement can be successfully used to shift coordination patterns, which has potential in the rehabilitation of movement disorders.

A Micro-Computed Tomography Technique to Study the Quality of Fibre Optics Embedded in Composite Materials

Directory of Open Access Journals (Sweden)

Gabriele Chiesura

2015-05-01

Full Text Available Quality of embedment of optical fibre sensors in carbon fibre-reinforced polymers plays an important role in the resultant properties of the composite, as well as for the correct monitoring of the structure. Therefore, availability of a tool able to check the optical fibre sensor-composite interaction becomes essential. High-resolution 3D X-ray Micro-Computed Tomography, or Micro-CT, is a relatively new non-destructive inspection technique which enables investigations of the internal structure of a sample without actually compromising its integrity. In this work the feasibility of inspecting the position, the orientation and, more generally, the quality of the embedment of an optical fibre sensor in a carbon fibre reinforced laminate at unit cell level have been proven.

Confinement of Reinforced-Concrete Columns with Non-Code Compliant Confining Reinforcement plus Supplemental Pen-Binder

Directory of Open Access Journals (Sweden)

Anang Kristianto

2012-11-01

Full Text Available One of the important requirements for earthquake resistant building related to confinement is the use of seismic hooks in the hoop or confining reinforcement of reinforced-concrete column elements. However, installation of a confining reinforcement with a 135-degree hook is not easy. Therefore, in practice, many construction workers apply a confining reinforcement with a 90-degreehook (non-code compliant. Based on research and records of recent earthquakes in Indonesia, the use of a non-code compliant confining reinforcement for concrete columns produces structures with poor seismic performance. This paper presents a study that introduces an additional element that is expected to improve the effectiveness of concrete columns confined with a non-code compliant confining reinforcement. The additional element, named a pen-binder, is used to keep the non-code compliant confining reinforcement in place. The effectiveness of this element under pure axial concentric loading was investigatedcomprehensively.The specimens tested in this study were 18 concrete columns,with a cross-section of 170 mm x 170 mm and a height of 480 mm. The main test variables were the material type of the pen-binder, the angle of the hook, and the confining reinforcement configuration.The test results indicate that adding pen-binders can effectively improve the strength and ductility of the column specimens confined with a non-code compliant confining reinforcement

Repairing reinforced concrete slabs using composite layers

International Nuclear Information System (INIS)

Naghibdehi, M. Ghasemi; Sharbatdar, M.K.; Mastali, M.

2014-01-01

There are several strengthening methods for rehabilitation of RC structural elements. The efficiency of these methods has been demonstrated by many researchers. Due to their mechanical properties, using fibrous materials in rehabilitation applications is growing fast. Therefore, this study presents rehabilitation of slabs in such a way that plain concrete layers on top, on bottom, on the entire cross section are replaced by reinforced concrete layers. In order to reinforce the concrete, Polypropylene (PP) and steel fibers were used by 0.5%, 1% and 2% fiber volume fractions. Nineteen slabs were studied under flexural loadings and fibrous material effects on the initial crack force, the maximum loading carrying capacity, absorbed energy and ductility were investigated. The obtained results demonstrated that increasing the fiber volume fraction or using reinforced concrete layer on top, bottom, or at the entire cross section of the slabs not only always leads to improvement in the slab performance, but also sometimes debilitates the slab performance. Hence, this study will propose the best positioning of reinforced concrete layer, fiber volume fraction and fiber type to achieve the best flexural performance of slabs. - Highlights: • Using PP fibers at the bottom layer led to the best slab performance in bending. • Using steel fiber at the top layer and entire cross-section led to the best slab performance. • Maximum increase in the initial crack force and loading were obtained at 2% steel fiber. • Maximum increase in the initial crack force and loading were obtained at 1% PP fiber

Influence of reinforcement's corrosion into hyperstatic reinforced concrete beams: a probabilistic failure scenarios analysis

Directory of Open Access Journals (Sweden)

G. P. PELLIZZER

Full Text Available AbstractThis work aims to study the mechanical effects of reinforcement's corrosion in hyperstatic reinforced concrete beams. The focus is the probabilistic determination of individual failure scenarios change as well as global failure change along time. The limit state functions assumed describe analytically bending and shear resistance of reinforced concrete rectangular cross sections as a function of steel and concrete resistance and section dimensions. It was incorporated empirical laws that penalize the steel yield stress and the reinforcement's area along time in addition to Fick's law, which models the chloride penetration into concrete pores. The reliability theory was applied based on Monte Carlo simulation method, which assesses each individual probability of failure. The probability of global structural failure was determined based in the concept of failure tree. The results of a hyperstatic reinforced concrete beam showed that reinforcements corrosion make change into the failure scenarios modes. Therefore, unimportant failure modes in design phase become important after corrosion start.

TiB2/Al2O3 ceramic particle reinforced aluminum fabricated by spray deposition

International Nuclear Information System (INIS)

Chen Xing; Yang Chengxiao; Guan Leding; Yan Biao

2008-01-01

Aluminum matrix ceramic particle reinforced composites (AMCs) is a kind of composite with great importance. Aluminum matrix composite reinforced with TiB 2 /Al 2 O 3 ceramic particles was successfully in situ synthesized in Al-TiO 2 -B 2 O 3 system in this paper, using spray deposition with hot-press treatment technique. Five groups of composites with different reinforcement volume contents were prepared and the comparisons of porosity, ultimate tensile strength (UTS), elongation and Brinell hardness (BH) between the composites with and without hot-press treating were carried out. The composite with 21.0% reinforcement volume content was analyzed by X-ray diffraction (XRD), Environmental Scanning Electron Microscope (ESEM), Transmission Electron Microscope (TEM) and Energy Disperse Spectroscopy (EDS). The results revealed the formation and uniform distribution of fine reinforcements in the matrix after hot-press treating, while a new intermetallic phase Al 3 Ti was found besides TiB 2 /Al 2 O 3 ceramic phase

In situ carbon nanotube reinforcements in a plasma-sprayed aluminum oxide nanocomposite coating

International Nuclear Information System (INIS)

Balani, K.; Zhang, T.; Karakoti, A.; Li, W.Z.; Seal, S.; Agarwal, A.

2008-01-01

Carbon nanotubes (CNT) are potential reinforcements for toughening the ceramic matrix. The critical issue of avoiding CNT agglomeration and introducing CNT-matrix anchoring has challenged many researchers to improve the mechanical properties of the CNT reinforced nanocomposite. In the current work, dispersed CNTs are grown on Al 2 O 3 powder particles in situ by the catalytic chemical vapor deposition (CCVD) technique. Consequently, 0.5 wt.% CNT-reinforced Al 2 O 3 particles were successfully plasma sprayed to obtain a 400 μm thick coating on the steel substrate. In situ CNTs grown on Al 2 O 3 shows a promising enhancement in hardness and fracture toughness of the plasma-sprayed coating attributed to the existence of strong metallurgical bonding between Al 2 O 3 particles and CNTs. In addition, CNT tentacles have imparted multi-directional reinforcement in securing the Al 2 O 3 splats. High-resolution transmission electron microscopy shows interfacial fusion between Al 2 O 3 and CNT and the formation of Y-junction nanotubes

Development of carbon nanotubes reinforced hydroxyapatite composite coatings on titanium by electrodeposition method

International Nuclear Information System (INIS)

Gopi, D.; Shinyjoy, E.; Sekar, M.; Surendiran, M.; Kavitha, L.; Sampath Kumar, T.S.

2013-01-01

Highlights: •Successful development of CNTs reinforced HAP coating on Ti by electrodeposition. •CNTs as a reinforcing material imparts strength and toughness to HAP. •Incorporating CNTs improves crystallinity, morphology, biological properties of HAP. •CNTs–HAP coating on Ti is bioresistive, better candidate for implant applications. -- Abstract: Carbon nanotubes (CNTs) are outstanding reinforcement material for imparting strength and toughness to brittle hydroxyapatite (HAP). This work reports the electrodeposition of CNTs reinforced HAP on titanium substrate at −1.4 V vs. SCE during 30 min with the functionalised CNTs concentration ranging from 0 to 2 wt.%. Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) equipped with energy dispersive X-ray analysis (EDX), high resolution transmission electron microscopy (HRTEM), mechanical and biological studies were used to characterise the coatings. Also, the corrosion resistance of the coatings was evaluated by electrochemical techniques in simulated body fluid (SBF) solution

Seawater infiltration effect on thermal degradation of fiber reinforced epoxy composites

Science.gov (United States)

Ibrahim, Mohd Haziq Izzuddin bin; Hassan, Mohamad Zaki bin; Ibrahim, Ikhwan; Rashidi, Ahmad Hadi Mohamed; Nor, Siti Fadzilah M.; Daud, Mohd Yusof Md

2018-05-01

Seawater salinity has been associated with the reduction of polymer structure durability. The aim of this study is to investigate the change in thermal degradation of fiber reinforced epoxy composite due to the presence of seawater. Carbon fiber, carbon/kevlar, fiberglass, and jute that reinforced with epoxy resin was laminated through hand-layup technique. Initially, these specimen was sectioned to 5×5 mm dimension, then immersed in seawater and distilled water at room temperature until it has thoroughly saturated. Following, the thermal degradation analysis using Differential Scanning Calorimetry (DSC), the thermic changes due to seawater infiltration was defined. The finding shows that moisture absorption reduces the glass transition temperature (Tg) of fiber reinforced epoxy composite. However, the glass transition temperature (Tg) of seawater infiltrated laminate composite is compareable with distilled water infiltrated laminate composite. The carbon fiber reinfored epoxy has the highest glass transition temperature out of all specimen.

Effect of nanoclay on durability and mechanical properties of flax fabric reinforced geopolymer composites

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H. Assaedi

2017-03-01

Full Text Available The main concern of using natural fibres as reinforcement in geopolymer composites is the durability of the fibres. Geopolymers are alkaline in nature because of the alkaline solution that is required for activating the geopolymer reaction. The alkalinity of the matrix, however, is the key reason of the degradation of natural fibres. The purpose of this study is to determine the effect of nanoclay (NC loading on the mechanical properties and durability of flax fabric (FF reinforced geopolymer composites. The durability of composites after 4 and 32 weeks at ambient temperature is presented. The microstructure of geopolymer matrices was investigated using X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and scanning electron microscopy (SEM. The results showed that the incorporation of NC has a positive impact on the physical properties, mechanical performance, and durability of FF reinforced geopolymer composites. The presence of NC has a positive impact through accelerating the geopolymerization, reducing the alkalinity of the system and increasing the geopolymer gel.

Degradation of normal portland and slag cement concrete under load, due to reinforcement corrosion

International Nuclear Information System (INIS)

Philipose, K.E.; Beaudoin, J.J.; Feldman, R.F.

1992-08-01

The corrosion of reinforcement is one of the major degradation mechanisms of reinforced concrete elements. The majority of studies published on concrete-steel corrosion have been conducted on unstressed specimens. Structural concrete, however, is subjected to substantial strain near the steel reinforcing bars that resist tensile loads, which results in a system of microcracks. This report presents the initial results of an investigation to determine the effect of applied load and microcracking on the rate of ingress of chloride ion and corrosion of steel in concrete. Simply-supported concrete beam specimens were loaded to give a maximum strain of about 600 με on the tension face. Chloride ion ingress on cores taken from loaded specimens was monitored using energy-dispersive X-ray analysis techniques. Corrosion current and rate measurements using linear polarization electrochemical techniques were also obtained on the same loaded specimens. Variables investigated included two concrete types, two steel cover-depths, three applied load levels, bonded and unbonded rebars and the exposure of tension and compression beam faces to chloride solution. One concrete mixture was made with type 10 Portland cement, the other with 75% blast furnace slag, 22% type 50 cement and 3% silica fume. The rate of chloride ion ingress into reinforced concrete, and hence the time for chloride ion to reach the reinforcing steel, is shown to be dependent on applied load and the concrete quality. The dependence of corrosion process descriptors - passive layer formation, initiation period and propagation period - on the level of applied load is discussed. (Author) (6 refs., 3 tabs., 10 figs.)

ECAP – New consolidation method for production of aluminium matrix composites with ceramic reinforcement

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Mateja Šnajdar Musa

2013-06-01

Full Text Available Aluminium based metal matrix composites are rapidly developing group of materials due to their unique combination of properties that include low weight, elevated strength, improved wear and corrosion resistance and relatively good ductility. This combination of properties is a result of mixing two groups of materials with rather different properties with aluminium as ductile matrix and different oxides and carbides added as reinforcement. Al2O3, SiC and ZrO2 are the most popular choices of reinforcement material. One of the most common methods for producing this type of metal matrix composites is powder metallurgy since it has many variations and also is relatively low-cost method. Many different techniques of compacting aluminium and ceramic powders have been previously investigated. Among those techniques equal channel angular pressing (ECAP stands out due to its beneficial influence on the main problem that arises during powder compaction and that is a non-uniform distribution of reinforcement particles. This paper gives an overview on ECAP method principles, advantages and produced powder composite properties.

Mechanical Behavior of Stainless Steel Fiber-Reinforced Composites Exposed to Accelerated Corrosion

Science.gov (United States)

O’Brien, Caitlin; McBride, Amanda; E. Zaghi, Arash; Burke, Kelly A.; Hill, Alex

2017-01-01

Recent advancements in metal fibers have introduced a promising new type of stainless steel fiber with high stiffness, high failure strain, and a thickness corrosion. The main goal of this study is to compare the impact of corrosion on the mechanical properties of steel fiber-reinforced composites with those of conventional types of stainless steel. By providing experimental evidences, this study may promote the application of steel fiber-reinforced composite as a viable alternative to conventional metals. Samples of steel fiber-reinforced polymer and four different types of stainless steel were subjected to 144 and 288 h of corrosion in ferric chloride solution to simulate accelerated corrosion conditions. The weight losses due to corrosion were recorded. The corroded and control samples were tested under monotonic tensile loading to measure the ultimate stresses and strains. The effect of corrosion on the mechanical properties of the different materials was evaluated. The digital image correlation (DIC) technique was used to investigate the failure mechanism of the corrosion-damaged specimens. Overall, steel fiber-reinforced composites had the greatest corrosion resistance. PMID:28773132

Experimental and Empirical Time to Corrosion of Reinforced Concrete Structures under Different Curing Conditions

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Ahmed A. Abouhussien

2014-01-01

Full Text Available Reinforced concrete structures, especially those in marine environments, are commonly subjected to high concentrations of chlorides, which eventually leads to corrosion of the embedded reinforcing steel. The total time to corrosion of such structures may be divided into three stages: corrosion initiation, cracking, and damage periods. This paper evaluates, both empirically and experimentally, the expected time to corrosion of reinforced concrete structures. The tested reinforced concrete samples were subjected to ten alternative curing techniques, including hot, cold, and normal temperatures, prior to testing. The corrosion initiation, cracking, and damage periods in this investigation were experimentally monitored by an accelerated corrosion test performed on reinforced concrete samples. Alternatively, the corrosion initiation time for counterpart samples was empirically predicted using Fick’s second law of diffusion for comparison. The results showed that the corrosion initiation periods obtained experimentally were comparable to those obtained empirically. The corrosion initiation was found to occur at the first jump of the current measurement in the accelerated corrosion test which matched the half-cell potential reading of around −350 mV.

Modeling the Structural Response of Reinforced Glass Beams using an SLA Scheme

NARCIS (Netherlands)

Louter, P.C.; Graaf, van de Anne; Rots, J.G.; Bos, Freek; Louter, Pieter Christiaan; Veer, Fred

2010-01-01

This paper investigates whether a novel computational sequentially linear analysis (SLA) technique, which is especially developed for modeling brittle material response, is applicable for modeling the structural response of metal reinforced glass beams. To do so, computational SLA results are

Finite element modeling of reinforced concrete beams with a hybrid combination of steel and aramid reinforcement

International Nuclear Information System (INIS)

Hawileh, R.A.

2015-01-01

Highlights: • Modeling of concrete beams reinforced steel and FRP bars. • Developed finite element models achieved good results. • The models are validated via comparison with experimental results. • Parametric studies are performed. - Abstract: Corrosion of steel bars has an adverse effect on the life-span of reinforced concrete (RC) members and is usually associated with crack development in RC beams. Fiber reinforced polymer (FRP) bars have been recently used to reinforce concrete members in flexure due to their high tensile strength and superior corrosion resistance properties. However, FRP materials are brittle in nature, thus RC beams reinforced with such materials would exhibit a less ductile behavior when compared to similar members reinforced with conventional steel reinforcement. Recently, researchers investigated the performance of concrete beams reinforced with a hybrid combination of steel and Aramid Fiber Reinforced Polymer (AFRP) reinforcement to maintain a reasonable level of ductility in such members. The function of the AFRP bars is to increase the load-carrying capacity, while the function of the steel bars is to ensure ductility of the flexural member upon yielding in tension. This paper presents a three-dimensional (3D) finite element (FE) model that predicted the load versus mid-span deflection response of tested RC beams conducted by other researchers with a hybrid combination of steel and AFRP bars. The developed FE models account for the constituent material nonlinearities and bond–slip behavior between the reinforcing bars and adjacent concrete surfaces. It was concluded that the developed models can accurately capture the behavior and predicts the load-carrying capacity of such RC members. In addition, a parametric study is conducted using the validated models to investigate the effect of AFRP bar size, FRP material type, bond–slip action, and concrete compressive strength on the performance of concrete beams when reinforced

Health monitoring of precast bridge deck panels reinforced with glass fiber reinforced polymer (GFRP) bars.

Science.gov (United States)

2012-03-01

The present research project investigates monitoring concrete precast panels for bridge decks that are reinforced with Glass Fiber Reinforced Polymer (GFRP) bars. Due to the lack of long term research on concrete members reinforced with GFRP bars, lo...

Modified precision lingual bonding technique: A step-wise approach with torque angulation device-bracket positioning device

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Rosaline Tina Paul

2017-01-01

Full Text Available Objectives: Contemporary preadjusted edgewise appliance is all about the precision in bracket design, prescription and positioning in addition to the orthodontist's skill and training. However, achieving it is a bigger challenge as the anatomy of the lingual surface of a tooth is uneven, dissimilar, and moreover the tooth alignment on the lingual surface is variant. Thus, the need for an accurate method of bracket positioning with predetermined torque and angulation incorporated in the brackets according to the patients' need is of key importance. Materials and Methods: A TAD-BPD machine used to enhance the accuracy of bracket positioning and bioplast accurate tray transfer technique was used. Results: A step-wise procedures in bracket positioning and fabricating an indirect bonding tray for lingual orthodontics using the torque angulation device-bracket positioning device. Conclusions: This technique facilitated unhindered bonding even in severely crowded cases and easy rebonding during mid-treatment stages.

Prior methylphenidate self-administration alters the subsequent reinforcing effects of methamphetamine in rats.

Science.gov (United States)

Baladi, Michelle G; Nielsen, Shannon M; Umpierre, Anthony; Hanson, Glen R; Fleckenstein, Annette E

2014-12-01

Methylphenidate (MPD) is clinically effective in treating the symptoms of attention-deficit hyperactivity disorder; however, its relatively widespread availability has raised public health concerns on nonmedical use of MPD among certain adult populations. Most preclinical studies investigate whether presumed therapeutically relevant doses of MPD alter sensitivity to the reinforcing effects of other drugs, but it remains unclear whether doses of MPD likely exceeding therapeutic relevance impact the subsequent reinforcing effects of drugs. To begin to address this question, the effect of prior MPD self-administration (0.56 mg/kg/infusion) on the subsequent reinforcing effects of methamphetamine (METH, 0.032 or 0.1 mg/kg/infusion) was investigated in male Sprague-Dawley rats. For comparison, it was also determined whether prior experimenter-administered MPD, injected daily at a presumed therapeutically relevant dose (2 mg/kg), altered the subsequent reinforcing effects of METH. Results indicated that, under the current conditions, only a history of MPD self-administration increased sensitivity to the subsequent reinforcing effects of METH. Furthermore, MPD did not impact food-maintained responding, suggesting that the effect of MPD might be specific to drug reinforcers. These data suggest that short-term, nonmedical use of MPD might alter the positive reinforcing effects of METH in a manner relevant to vulnerability to drug use in humans.

Strength resistance of reinforced concrete elements of high-rise buildings under dynamic loads

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Berlinov Mikhail

2018-01-01

Full Text Available A new method for calculating reinforced concrete constructions of high-rise buildings under dynamic loads from wind, seismic, transport and equipment based on the initial assumptions of the modern phenomenological theory of a nonlinearly deformable elastic-creeping body is proposed. In the article examined the influence of reinforcement on the work of concrete in the conditions of triaxial stress-strain state, based on the compatibility of the deformation of concrete and reinforcement. Mathematical phenomenological equations have been obtained that make it possible to calculate the reinforced concrete elements working without and with cracks. A method for linearizing of these equations based on integral estimates is proposed, which provides the fixation of the vibro-creep processes in the considered period of time. Application of such a technique using the finite-difference method, step method and successive approximations will allow to find a numerical solution of the problem. Such an approach in the design of reinforced concrete constructions will allow not only more fully to take into account the real conditions of their work, revealing additional reserves of load capacity, but also to open additional opportunities for analysis and forecasting their functioning at various stages of operation.

Strength resistance of reinforced concrete elements of high-rise buildings under dynamic loads

Science.gov (United States)

Berlinov, Mikhail

2018-03-01

A new method for calculating reinforced concrete constructions of high-rise buildings under dynamic loads from wind, seismic, transport and equipment based on the initial assumptions of the modern phenomenological theory of a nonlinearly deformable elastic-creeping body is proposed. In the article examined the influence of reinforcement on the work of concrete in the conditions of triaxial stress-strain state, based on the compatibility of the deformation of concrete and reinforcement. Mathematical phenomenological equations have been obtained that make it possible to calculate the reinforced concrete elements working without and with cracks. A method for linearizing of these equations based on integral estimates is proposed, which provides the fixation of the vibro-creep processes in the considered period of time. Application of such a technique using the finite-difference method, step method and successive approximations will allow to find a numerical solution of the problem. Such an approach in the design of reinforced concrete constructions will allow not only more fully to take into account the real conditions of their work, revealing additional reserves of load capacity, but also to open additional opportunities for analysis and forecasting their functioning at various stages of operation.

Robustness Area Technique Developing Guidelines for Power System Restoration

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Paulo Murinelli Pesoti

2017-01-01

Full Text Available This paper proposes a novel energy based technique called the Robustness Area (RA technique that measures power system robustness levels, as a helper for planning Power System Restorations (PSRs. The motivation is on account of the latest blackouts in Brazil, where the local Independent System Operator (ISO encountered difficulties related to circuit disconnections during the restoration. The technique identifies vulnerable and robust buses, pointing out system areas that should be firstly reinforced during PSR, in order to enhance system stability. A Brazilian power system restoration area is used to compare the guidelines adopted by the ISO with a more suitable new plan indicated by the RA tool. Active power and reactive power load margin and standing phase angle show the method efficiency as a result of a well balanced system configuration, enhancing the restoration performance. Time domain simulations for loop closures and severe events also show the positive impact that the proposed tool brings to PSRs.

Elastomeric Polymers for Retrofitting of Reinforced Concrete Structures against the Explosive Effects of Blast

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S. N. Raman

2012-01-01

Full Text Available The main distinction of blast load from other types of dynamic loadings is its impulsive nature, where the loads usually act for a very short duration but transmit very high impulsive pressures. This paper presents an overview of the present retrofitting techniques in use to enhance the capacity of structural elements to withstand the effects of blast loads, and introduces an alternative retrofitting approach by utilizing polymer coatings. The authors have demonstrated the positive effects of this approach by conducting a numerical investigation on the behavior of an unretrofitted reinforced concrete panel subjected to the blast load from a 2 kg charge at 1.6 m stand-off distance, and subsequently comparing its performance with several polymer coated panels. The analysis was performed by using an explicit nonlinear finite element (FE code. The results demonstrate the contributions of this technique in terms of panel displacement control and energy dissipation. Considering that the polymer coating can also act as a protective layer in improving the durability of structural materials, this technique can also be optimized favorably to enhance the overall sustainability of structures.

Distal Oblique Bundle Reinforcement for Treatment of DRUJ Instability.

Science.gov (United States)

Brink, Peter R G; Hannemann, Pascal F W

2015-08-01

Background Chronic, dynamic bidirectional instability in the distal radioulnar joint (DRUJ) is diagnosed clinically, based on the patient's complaints and the finding of abnormal laxity in the vicinity of the distal ulna. In cases where malunion is ruled out or treated and there are no signs of osteoarthritis, stabilization of the DRUJ may offer relief. To this end, several different techniques have been investigated over the past 90 years. Materials and Methods In this article we outline the procedure for a new technique using a tendon graft to reinforce the distal edge of the interosseous membrane. Description of Technique A percutaneous technique is used to harvest the palmaris longus tendon and to create a tunnel, just proximal to the sigmoid notch, through the ulna and radius in an oblique direction. By overdrilling the radial cortex, the knotted tendon can be pulled through the radius and ulna and the knot blocked at the second radial cortex, creating a strong connection between the radius and ulna at the site of the distal oblique bundle (DOB). The tendon is fixed in the ulna with a small interference screw in full supination, preventing subluxation of the ulna out of the sigmoid notch during rotation. Results Fourteen patients were treated with this novel technique between 2011 and October 2013. The QuickDASH score at 25 months postoperatively (range 16-38 months) showed an improvement of 32 points. Similarly, an improvement of 33 points (67-34 months) was found on the PRWHE. Only one recurrence of chronic, dynamic bidirectional instability in the DRUJ was observed. Conclusion This simple percutaneous tenodesis technique between radius and ulna at the position of the distal edge of the interosseous membrane shows promise in terms of both restoring stability and relieving complaints related to chronic subluxation in the DRUJ.

A study on the crushing behavior of basalt fiber reinforced composite structures

Science.gov (United States)

Pandian, A.; Veerasimman, A. P.; Vairavan, M.; Francisco, C.; Sultan, M. T. H.

2016-10-01

The crushing behavior and energy absorption capacity of basalt fiber reinforced hollow square structure composites are studied under axial compression. Using the hand layup technique, basalt fiber reinforced composites were fabricated using general purpose (GP) polyester resin with the help of wooden square shaped mould of varying height (100 mm, 150 mm and 200 mm). For comparison, similar specimens of glass fiber reinforced polymer composites were also fabricated and tested. Axial compression load is applied over the top end of the specimen with cross head speed as 2 mm/min using Universal Testing Machine (UTM). From the experimental results, the load-deformation characteristics of both glass fiber and basalt fiber composites were investigated. Crashworthiness and mode of collapse for the composites were determined from load-deformation curve, and they were then compared to each other in terms of their crushing behaviors.

Review on preparation techniques of particle reinforced metal matrix composites

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HAO Bin

2006-02-01

Full Text Available This paper reviews the investigation status of the techniques for preparation of metal matrix composites and the research outcomes achieved recently. The mechanisms, characteristics, application ranges and levels of development of these preparation techniques are analyzed. The advantages and the disadvantages of each technique are synthetically evaluated. Lastly, the future directions of research and the prospects for the preparation techniques of metal matrix composites are forecasted.

Effects of reinforcer magnitude on responding under differential-reinforcement-of-low-rate schedules of rats and pigeons.

Science.gov (United States)

Doughty, Adam H; Richards, Jerry B

2002-07-01

Experiment I investigated the effects of reinforcer magnitude on differential-reinforcement-of-low-rate (DRL) schedule performance in three phases. In Phase 1, two groups of rats (n = 6 and 5) responded under a DRI. 72-s schedule with reinforcer magnitudes of either 30 or 300 microl of water. After acquisition, the water amounts were reversed for each rat. In Phase 2, the effects of the same reinforcer magnitudes on DRL 18-s schedule performance were examined across conditions. In Phase 3, each rat responded unider a DR1. 18-s schedule in which the water amotnts alternated between 30 and 300 microl daily. Throughout each phase of Experiment 1, the larger reinforcer magnitude resulted in higher response rates and lower reinforcement rates. The peak of the interresponse-time distributions was at a lower value tinder the larger reinforcer magnitude. In Experiment 2, 3 pigeons responded under a DRL 20-s schedule in which reinforcer magnitude (1-s or 6-s access to grain) varied iron session to session. Higher response rates and lower reinforcement rates occurred tinder the longer hopper duration. These results demonstrate that larger reinforcer magnitudes engender less efficient DRL schedule performance in both rats and pigeons, and when reinforcer magnitude was held constant between sessions or was varied daily. The present results are consistent with previous research demonstrating a decrease in efficiency as a function of increased reinforcer magnituide tinder procedures that require a period of time without a specified response. These findings also support the claim that DRI. schedule performance is not governed solely by a timing process.

Multi-Objective Patch Optimization with Integrated Kinematic Draping Simulation for Continuous–Discontinuous Fiber-Reinforced Composite Structures

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Benedikt Fengler

2018-03-01

Full Text Available Discontinuous fiber-reinforced polymers (DiCoFRP in combination with local continuous fiber reinforced polymers (CoFRP provide both a high design freedom and high weight-specific mechanical properties. For the optimization of CoFRP patches on complexly shaped DiCoFRP structures, an optimization strategy is needed which considers manufacturing constraints during the optimization procedure. Therefore, a genetic algorithm is combined with a kinematic draping simulation. To determine the optimal patch position with regard to structural performance and overall material consumption, a multi-objective optimization strategy is used. The resulting Pareto front and a corresponding heat-map of the patch position are useful tools for the design engineer to choose the right amount of reinforcement. The proposed patch optimization procedure is applied to two example structures and the effect of different optimization setups is demonstrated.

Metallic Glasses as Potential Reinforcements in Al and Mg Matrices: A Review

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S. Jayalakshmi

2018-04-01

Full Text Available Development of metal matrix composites (MMCs with metallic glass/amorphous alloy reinforcements is an emerging research field. As reinforcements, metallic glasses with their high strength (up to ~2 GPa and high elastic strain limit (~2% can provide superior mechanical properties. Being metallic in nature, the glassy alloys can ensure better interfacial properties when compared to conventional ceramic reinforcements. Given the metastable nature of metallic glasses, lightweight materials such as aluminum (Al and magnesium (Mg with relatively lower melting points are suitable matrix materials. Synthesis of these advanced composites is a challenge as selection of processing method and appropriate reinforcement type (which does not allow devitrification of the metallic glass during processing is important. Non-conventional techniques such as high frequency induction sintering, bidirectional microwave sintering, friction stir processing, accumulative roll-bonding, and spark plasma sintering are being explored to produce these novel materials. In this paper, an overview on the synthesis and properties of aluminum and magnesium based composites with glassy reinforcement produced by various unconventional methods is presented. Evaluation of properties of the produced composites indicate: (i retention of amorphous state of the reinforcement after processing; (ii significant improvement in hardness and strength; (iii improvement/retention of ductility; and (iv high wear resistance and low coefficient of friction. Further, a comparative understanding of the properties highlights that the selection of the processing method is important in producing high performance composites.

Experimental Exploration of Metal Cable as Reinforcement in 3D Printed Concrete.

Science.gov (United States)

Bos, Freek P; Ahmed, Zeeshan Y; Jutinov, Evgeniy R; Salet, Theo A M

2017-11-16

The Material Deposition Method (MDM) is enjoying increasing attention as an additive method to create concrete mortar structures characterised by a high degree of form-freedom, a lack of geometrical repetition, and automated construction. Several small-scale structures have been realised around the world, or are under preparation. However, the nature of this construction method is unsuitable for conventional reinforcement methods to achieve ductile failure behaviour. Sometimes, this is solved by combining printing with conventional casting and reinforcing techniques. This study, however, explores an alternative strategy, namely to directly entrain a metal cable in the concrete filament during printing to serve as reinforcement. A device is introduced to apply the reinforcement. Several options for online reinforcement media are compared for printability. Considerations specific to the manufacturing process are discussed. Subsequently, pull-out tests on cast and printed specimens provide an initial characterisation of bond behaviour. Bending tests furthermore show the potential of this reinforcement method. The bond stress of cables in printed concrete was comparable to values reported for smooth rebar but lower than that of the same cables in cast concrete. The scatter in experimental results was high. When sufficient bond length is available, ductile failure behaviour for tension parallel to the filament direction can be achieved, even though cable slip occurs. Further improvements to the process should pave the way to achieve better post-crack resistance, as the concept in itself is feasible.

The Impact Resistance of Fiber-Reinforced Polymer Composites: A Review

Directory of Open Access Journals (Sweden)

Mahmood Mehrdad Shokrieh

2012-12-01

Full Text Available Fiber reinforced composites are widely used instead of traditional materials in various technological applications. Therefore, by considering the extensive applications of these materials, a proper knowledge of their impact behavior (from low- to high-velocity as well as their static behavior is necessary. In order to study the effects of strain rates on the behavior of these materials, special testing machines are needed. Most of the research efforts in this feld are focused on application of real loading and gripping boundary conditions on the testing specimens. In this paper, a detailed review of different types of impact testing techniques and the strain rate dependence of mechanical and strength properties of polymer composite materials  are presented. In this respect, an attempt is made to present and summarize the methods of impact tests and the strain rate effects on the tensile, compressive, shear and bending properties of the fber-reinforced polymer composite materials. Moreover, a classifcation of the state-of-the-art of the testing techniques to characterize composite material properties in a wide range of strain rates are also given.

Reinforcement of cement-based matrices with graphite nanomaterials

Science.gov (United States)

Sadiq, Muhammad Maqbool

Cement-based materials offer a desirable balance of compressive strength, moisture resistance, durability, economy and energy-efficiency; their tensile strength, fracture energy and durability in aggressive environments, however, could benefit from further improvements. An option for realizing some of these improvements involves introduction of discrete fibers into concrete. When compared with today's micro-scale (steel, polypropylene, glass, etc.) fibers, graphite nanomaterials (carbon nanotube, nanofiber and graphite nanoplatelet) offer superior geometric, mechanical and physical characteristics. Graphite nanomaterials would realize their reinforcement potential as far as they are thoroughly dispersed within cement-based matrices, and effectively bond to cement hydrates. The research reported herein developed non-covalent and covalent surface modification techniques to improve the dispersion and interfacial interactions of graphite nanomaterials in cement-based matrices with a dense and well graded micro-structure. The most successful approach involved polymer wrapping of nanomaterials for increasing the density of hydrophilic groups on the nanomaterial surface without causing any damage to the their structure. The nanomaterials were characterized using various spectrometry techniques, and SEM (Scanning Electron Microscopy). The graphite nanomaterials were dispersed via selected sonication procedures in the mixing water of the cement-based matrix; conventional mixing and sample preparation techniques were then employed to prepare the cement-based nanocomposite samples, which were subjected to steam curing. Comprehensive engineering and durability characteristics of cement-based nanocomposites were determined and their chemical composition, microstructure and failure mechanisms were also assessed through various spectrometry, thermogravimetry, electron microscopy and elemental analyses. Both functionalized and non-functionalized nanomaterials as well as different

Basalt fiber reinforced polymer composites: Processing and properties

Science.gov (United States)

Liu, Qiang

A high efficiency rig was designed and built for in-plane permeability measurement of fabric materials. A new data derivation procedure to acquire the flow fluid pattern in the experiment was developed. The measurement results of the in-plane permeability for basalt twill 31 fabric material showed that a high correlation exists between the two principal permeability values for this fabric at 35% fiber volume fraction. This may be the most important scientific contribution made in this thesis. The results from radial measurements corresponded quite well with those from Unidirectional (UD) measurements, which is a well-established technique. No significant differences in mechanical properties were found between basalt fabric reinforced polymer composites and glass composites reinforced by a fabric of similar weave pattern. Aging results indicate that the interfacial region in basalt composites may be more vulnerable to environmental damage than that in glass composites. However, the basalt/epoxy interface may have been more durable than the glass/epoxy interface in tension-tension fatigue because the basalt composites have significantly longer fatigue life. In this thesis, chapter I reviews the literature on fiber reinforced polymer composites, with concentration on permeability measurement, mechanical properties and durability. Chapter II discusses the design of the new rig for in-plane permeability measurement, the new derivation procedure for monitoring of the fluid flow pattern, and the permeability measurement results. Chapter III compares the mechanical properties and durability between basalt fiber and glass fiber reinforced polymer composites. Lastly, chapter IV gives some suggestions and recommendations for future work.

The usage of carbon fiber reinforcement polymer and glass fiber reinforcement polymer for retrofit technology building

Science.gov (United States)

Tarigan, Johannes; Meka, Randi; Nursyamsi

2018-03-01

Fiber Reinforcement Polymer has been used as a material technology since the 1970s in Europe. Fiber Reinforcement Polymer can reinforce the structure externally, and used in many types of buildings like beams, columns, and slabs. It has high tensile strength. Fiber Reinforcement Polymer also has high rigidity and strength. The profile of Fiber Reinforcement Polymer is thin and light, installation is simple to conduct. One of Fiber Reinforcement Polymer material is Carbon Fiber Reinforcement Polymer and Glass Fiber Reinforcement Polymer. These materials is tested when it is installed on concrete cylinders, to obtain the comparison of compressive strength CFRP and GFRP. The dimension of concrete is diameter of 15 cm and height of 30 cm. It is amounted to 15 and divided into three groups. The test is performed until it collapsed to obtain maximum load. The results of research using CFRP and GFRP have shown the significant enhancement in compressive strength. CFRP can increase the compressive strength of 26.89%, and GFRP of 14.89%. For the comparison of two materials, CFRP is more strengthening than GFRP regarding increasing compressive strength. The usage of CFRP and GFRP can increase the loading capacity.

Titanium reinforced boron-polyimide composite

Science.gov (United States)

Clark, G. A.; Clayton, K. I.

1969-01-01

Processing techniques for boron polyimide prepreg were developed whereby composites could be molded under vacuum bag pressure only. A post-cure cycle was developed which resulted in no loss in room temperature mechanical properties of the composite at any time during up to 16 hours at 650 F. A design utilizing laminated titanium foil was developed to achieve a smooth transition of load from the titanium attachment points into the boron-reinforced body of the structure. The box beam test article was subjected to combined bending and torsional loads while exposed to 650 F. Loads were applied incrementally until failure occurred at 83% design limit load.

Application of ceramic short fiber reinforced Al alloy matrix composite on piston for internal combustion engines

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Wu Shenqing

2010-11-01

Full Text Available The preparation and properties of ceramic short fiber reinforced Al-Si alloy matrix composite and it’s application on the piston for internal combustion engines are presented. Alumina or aluminosilicate fibers reinforced Al-Si alloy matrix composite has more excellent synthetical properties at elevated temperature than the matrix alloys. A partially reinforced Al-Si alloy matrix composite piston produced by squeeze casting technique has a firm interface between reinforced and unreinforced areas, low reject rate and good technical tolerance. As a new kind of piston material, it has been used for mass production of about 400,000 pieces of automobile engines piston. China has become one of a few countries in which aluminum alloy matrix composite materials have been used in automobile industry and attained industrialization.

Numerical Study Of The Effects Of Preloading, Axial Loading And Concrete Shrinkage On Reinforced Concrete Elements Strengthened By Concrete Layers And Jackets

International Nuclear Information System (INIS)

Lampropoulos, A. P.; Dritsos, S. E.

2008-01-01

In this study, the technique of seismic strengthening existing reinforced concrete columns and beams using additional concrete layers and jackets is examined. The finite element method and the finite element program ATENA is used in this investigation. When a reinforced jacket or layer is being constructed around a column it is already preloaded due to existing service loads. This effect has been examined for different values of the axial load normalized to the strengthened column. The techniques of strengthening with a concrete jacket or a reinforced concrete layer on the compressive side of the column are examined. Another phenomenon that is examined in this study is the shrinkage of the new concrete of an additional layer used to strengthen an existing member. For this investigation, a simply supported beam with an additional reinforced concrete layer on the tensile side is examined. The results demonstrate that the effect of preloading is important when a reinforced concrete layer is being used with shear connectors between the old and the new reinforcement. It was also found that the shrinkage of the new concrete reduces the strength of the strengthened beam and induces an initial sliding between the old and the new concrete

Report on aging of nuclear power plant reinforced concrete structures

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

1996-03-01

The Structural Aging Program provides the US Nuclear Regulatory Commission with potential structural safety issues and acceptance criteria for use in continued service assessments of nuclear power plant safety-related concrete structures. The program was organized under four task areas: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technology, and Quantitative Methodology for Continued Service Determinations. Under these tasks, over 90 papers and reports were prepared addressing pertinent aspects associated with aging management of nuclear power plant reinforced concrete structures. Contained in this report is a summary of program results in the form of information related to longevity of nuclear power plant reinforced concrete structures, a Structural Materials Information Center presenting data and information on the time variation of concrete materials under the influence of environmental stressors and aging factors, in-service inspection and condition assessments techniques, repair materials and methods, evaluation of nuclear power plant reinforced concrete structures, and a reliability-based methodology for current and future condition assessments. Recommendations for future activities are also provided. 308 refs., 61 figs., 50 tabs

Report on aging of nuclear power plant reinforced concrete structures

Energy Technology Data Exchange (ETDEWEB)

Naus, D.J.; Oland, C.B. [Oak Ridge National Lab., TN (United States); Ellingwood, B.R. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering

1996-03-01

The Structural Aging Program provides the US Nuclear Regulatory Commission with potential structural safety issues and acceptance criteria for use in continued service assessments of nuclear power plant safety-related concrete structures. The program was organized under four task areas: Program Management, Materials Property Data Base, Structural Component Assessment/Repair Technology, and Quantitative Methodology for Continued Service Determinations. Under these tasks, over 90 papers and reports were prepared addressing pertinent aspects associated with aging management of nuclear power plant reinforced concrete structures. Contained in this report is a summary of program results in the form of information related to longevity of nuclear power plant reinforced concrete structures, a Structural Materials Information Center presenting data and information on the time variation of concrete materials under the influence of environmental stressors and aging factors, in-service inspection and condition assessments techniques, repair materials and methods, evaluation of nuclear power plant reinforced concrete structures, and a reliability-based methodology for current and future condition assessments. Recommendations for future activities are also provided. 308 refs., 61 figs., 50 tabs.

Adversarial Reinforcement Learning in a Cyber Security Simulation}

OpenAIRE

Elderman, Richard; Pater, Leon; Thie, Albert; Drugan, Madalina; Wiering, Marco

2017-01-01

This paper focuses on cyber-security simulations in networks modeled as a Markov game with incomplete information and stochastic elements. The resulting game is an adversarial sequential decision making problem played with two agents, the attacker and defender. The two agents pit one reinforcement learning technique, like neural networks, Monte Carlo learning and Q-learning, against each other and examine their effectiveness against learning opponents. The results showed that Monte Carlo lear...

Improving the corrosion resistance of AZ91D magnesium alloy through reinforcement with titanium carbides and borides

Directory of Open Access Journals (Sweden)

Mohamed Gobara

2015-06-01

Full Text Available A composite consisting of magnesium matrix reinforced with a network of TiC–Ti2AlC–TiB2 particulates has been fabricated using a practical in-situ reactive infiltration technique. The microstructural and phase composition of the magnesium matrix composite (R-Mg was investigated using SEM/EDS and XRD. The analyses revealed the complete formation of TiC, Ti2AlC and TiB2 particles in the magnesium matrix. Comparative compression tests of R-Mg and AZ91D alloy showed that the reinforcing particles improve the mechanical properties of Mg alloy. EIS and potentiodynamic polarization results indicated that the reinforcing particles significantly improve the corrosion resistance of the reinforced alloy in 3.5% NaCl solution.

Vibration technique for non-destructive testing of carbon fiber reinforced plastic structures

International Nuclear Information System (INIS)

Miller, W.G.

1982-01-01

For nondestructive testing of structures of KFK (carbon fiber reinforced plastics) Adams and a group at the English University of Bristol, Department of Mechanical Engineering have developed a vibrational testing method. It is based on the fact that the decreasing self-oscillations of a structure can be measured in connection with a dynamical analysis at only one particular location of that structure. This way a damage can be localized and be quantized rawly. The mathematical model is simple and for every tested structure only one analysis is needed. Many kinds of damages in structures can be determined and reproduced especially in structures that represent typical cases of application of KFK in air and aerospace industry. (orig.) [de

Reliability analysis of reinforced concrete grids with nonlinear material behavior

Energy Technology Data Exchange (ETDEWEB)

Neves, Rodrigo A [EESC-USP, Av. Trabalhador Sao Carlense, 400, 13566-590 Sao Carlos (Brazil); Chateauneuf, Alaa [LaMI-UBP and IFMA, Campus de Clermont-Fd, Les Cezeaux, BP 265, 63175 Aubiere cedex (France)]. E-mail: alaa.chateauneuf@ifma.fr; Venturini, Wilson S [EESC-USP, Av. Trabalhador Sao Carlense, 400, 13566-590 Sao Carlos (Brazil)]. E-mail: venturin@sc.usp.br; Lemaire, Maurice [LaMI-UBP and IFMA, Campus de Clermont-Fd, Les Cezeaux, BP 265, 63175 Aubiere cedex (France)

2006-06-15

Reinforced concrete grids are usually used to support large floor slabs. These grids are characterized by a great number of critical cross-sections, where the overall failure is usually sudden. However, nonlinear behavior of concrete leads to the redistribution of internal forces and accurate reliability assessment becomes mandatory. This paper presents a reliability study on reinforced concrete (RC) grids based on coupling Monte Carlo simulations with the response surface techniques. This approach allows us to analyze real RC grids with large number of failure components. The response surface is used to evaluate the structural safety by using first order reliability methods. The application to simple grids shows the interest of the proposed method and the role of moment redistribution in the reliability assessment.

Prediction of reinforcement corrosion using corrosion induced cracks width in corroded reinforced concrete beams

International Nuclear Information System (INIS)

Khan, Inamullah; François, Raoul; Castel, Arnaud

2014-01-01

This paper studies the evolution of reinforcement corrosion in comparison to corrosion crack width in a highly corroded reinforced concrete beam. Cracking and corrosion maps of the beam were drawn and steel reinforcement was recovered from the beam to observe the corrosion pattern and to measure the loss of mass of steel reinforcement. Maximum steel cross-section loss of the main reinforcement and average steel cross-section loss between stirrups were plotted against the crack width. The experimental results were compared with existing models proposed by Rodriguez et al., Vidal et al. and Zhang et al. Time prediction models for a given opening threshold are also compared to experimental results. Steel cross-section loss for stirrups was also measured and was plotted against the crack width. It was observed that steel cross-section loss in the stirrups had no relationship with the crack width of longitudinal corrosion cracks. -- Highlights: •Relationship between crack and corrosion of reinforcement was investigated. •Corrosion results of natural process and then corresponds to in-situ conditions. •Comparison with time predicting model is provided. •Prediction of load-bearing capacity from crack pattern was studied

Study of the internal confinement of concrete reinforced (in civil engineering) with woven reinforcement

Science.gov (United States)

Dalal, M.; Goumairi, O.; El Malik, A.

2017-10-01

Concrete is generally the most used material in the field of construction. Despite its extensive use in structures, it represents some drawbacks related to its properties including its low tensile strength and low ductility. To solve this problem, the use of steel reinforcement in concrete structures is possible. Another possibility is the introduction of different types of continuous fibre / staple in the concrete, such as steel fibres or synthetic fibres, to obtain ″Concretes bundles″. Many types of fibre concrete, which have been developed and for many of them, the gain provided by the fibre was rather low and no significant improvement in tensile strength was really reaching. By cons, the ductility was higher than that of ordinary concrete. The objective of this study is to examine concrete reinforcement by inserting reinforcements woven polyester. These are either woven bidirectional (2D) or three-dimensional woven (3D). So we will report the properties of each type of reinforcement and the influence of the method of weaving on the strength reinforcements and on the strength of concrete in which they are incorporated. Such influence should contribute to improving the sustainability and enhancement of reinforcement

Flexural Behaviour of Reinforced Fibrous Concrete Beams: Experiments and Analytical Modelling

International Nuclear Information System (INIS)

Hameed, R.; Sellier, A.; Turatsinze, A.; Duprat, F.

2013-01-01

Flexural behaviour of reinforced fibrous concrete beams was investigated in this research study. Two types of metallic fibers were studied: amorphous metallic fibers (FibraFlex fibers), and carbon steel hooked-end fibers (Dramix fibers). Four types of reinforced concretes were made: one control (without fibers) and three fibrous. Among three reinforced fibrous concretes, two contained fibers in mono form and one contained fibers in hybrid form. The total quantity of fibers in mono and hybrid forms was 20 kg/m3 and 40 kg/m3, respectively. Three point bending tests were performed according to European standards NF EN 14651 on beams of 150 x 150 mm cross section and length of 550 mm. The results showed that due to positive synergetic interaction between the two metallic fibers used, reinforced fibrous concret (RFC) beams containing fibers in hybrid form exhibited better response at all loading stages. Analytical model to predict ultimate moment capacity of the RFC beam of rectangular section was developed and is presented in this paper. Analytical results for ultimate moment were found to be in good agreement with experimental results. (author)

A new approach to assess gambling-like behavior in laboratory rats: using intracranial self-stimulation as a positive reinforcer

Directory of Open Access Journals (Sweden)

Stephanie E Tedford

2014-06-01

Full Text Available Pathological gambling is one manifestation of impulse control disorders. The biological underpinnings of these disorders remain elusive and treatment is far from ideal. Animal models of impulse control disorders are a critical research tool for understanding this condition and for medication development. Modeling such complex behaviors is daunting, but by its deconstruction, scientists have recapitulated in animals critical aspects of gambling. One aspect of gambling is cost/benefit decision-making wherein one weighs the anticipated costs and expected benefits of a course of action. Risk/reward, delay-based and effort-based decision-making all represent cost/benefit choices. These features are studied in humans and have been translated to animal protocols to measure decision-making processes. Traditionally, the positive reinforcer used in animal studies is food. Here, we describe how intracranial self-stimulation can be used for cost/benefit decision-making tasks and overview our recent studies showing how pharmacological therapies alter these behaviors in laboratory rats. We propose that these models may have value in screening new compounds for the ability to promote and prevent aspects of gambling behavior.

Reinforcement Enhances Vigilance Among Children With ADHD: Comparisons to Typically Developing Children and to the Effects of Methylphenidate

Science.gov (United States)

Bubnik, Michelle G.; Hawk, Larry W.; Pelham, William E.; Waxmonsky, James G.; Rosch, Keri S.

2014-01-01

Sustained attention and reinforcement are posited as causal mechanisms in Attention-Deficit/Hyperactivity Disorder (ADHD), but their interaction has received little empirical study. In two studies, we examined the impact of performance-based reinforcement on sustained attention over time, or vigilance, among 9- to 12-year-old children. Study 1 demonstrated the expected vigilance deficit among children with ADHD (n=25; 12% female) compared to typically developing (TD) controls (n=33; 22% female) on a standard continuous performance task (CPT). During a subsequent visit, reinforcement improved attention more among children with ADHD than controls. Study 2 examined the separate and combined effects of reinforcement and acute methylphenidate (MPH) on CPT performance in children with ADHD (n=19; 21% female). Both reinforcement and MPH enhanced overall target detection and attenuated the vigilance decrement that occurred in no-reinforcement, placebo condition. Cross-study comparisons suggested that the combination of MPH and reinforcement eliminated the vigilance deficit in children with ADHD, normalizing sustained attention. This work highlights the clinically and theoretically interesting intersection of reinforcement and sustained attention. PMID:24931776

Structural Effects of Reinforced Concrete Beam Due to Corrosion

Science.gov (United States)

Noh, Hamidun Mohd; Idris, Nur'ain; Noor, Nurazuwa Md; Sarpin, Norliana; Zainal, Rozlin; Kasim, Narimah

2018-03-01

Corrosion of steel in reinforced concrete is one of the main issues among construction stakeholders. The main consequences of steel corrosion include loss of cross section of steel area, generation of expansive pressure which caused cracking of concrete, spalling and delaminating of the concrete cover. Thus, it reduces the bond strength between the steel reinforcing bar and concrete, and deteriorating the strength of the structure. The objective of this study is to investigate the structural effects of corrosion damage on the performance of reinforced concrete beam. A series of corroded reinforced concrete beam with a corrosion rate of 0%, 20% and 40% of rebar corrosion is used in parametric study to assess the influence of different level of corrosion rate to the structural performance. As a result, the used of interface element in the finite element modelling predicted the worst case of corrosion analysis since cracks is induced and generate at this surface. On the other hand, a positive linear relationship was sketched between the increase of expansive pressure and the corrosion rate. Meanwhile, the gradient of the graph is decreased with the increase of steel bar diameter. Furthermore, the analysis shows that there is a significant effect on the load bearing capacity of the structure where the higher corrosion rate generates a higher stress concentration at the mid span of the beam. This study could predict the residual strength of reinforced concrete beam under the corrosion using the finite element analysis. The experimental validation is needed on the next stage to investigate the quantitative relation between the corrosion rate and its influence on the mechanical properties.

The Reinforcing Event (RE) Menu

Science.gov (United States)

Addison, Roger M.; Homme, Lloyd E.

1973-01-01

A motivational system, the Contingency Management System, uses contracts in which some amount of defined task behavior is demanded for some interval of reinforcing event. The Reinforcing Event Menu, a list of high probability reinforcing behaviors, is used in the system as a prompting device for the learner and as an aid for the administrator in…

Systematic Review of Differential Reinforcement of Alternative Behavior Without Extinction for Individuals With Autism.

Science.gov (United States)

MacNaul, Hannah L; Neely, Leslie C

2018-05-01

The purpose of this article is to review the literature on differential reinforcement of alternative behavior procedures without extinction for individuals with autism. Using predetermined inclusion criteria, a total of 10 studies were included and summarized in terms of the following: (a) participant characteristics (e.g., sex, age, and diagnosis), (b) treatment setting, (c) problem behavior, (d) function, (e) alternative behavior, (f) intervention, (g) outcomes, and (h) conclusiveness of evidence. Of the 10 studies, nine demonstrated positive effects and one mixed effects. Five studies successfully reduced problem behavior by manipulating different reinforcement parameters (magnitude, immediacy, and quality) and four manipulated the schedule of reinforcement. One study had mixed results with two of the three participants requiring extinction. The findings of this review suggest that variations of differential reinforcement of alternative behavior interventions without an extinction component may be considered promising practices for the treatment of challenging behavior in individuals with autism.

High rate loading tests and impact tests of concrete and reinforcement

International Nuclear Information System (INIS)

Takeda, J.I.; Tachikawa, H.; Fujimoto, K.

1982-01-01

The responses of reinforced concrete structural members and structures subjected to impact or impulsive loadings are affected by the behavior of constituent concrete and reinforcement which are the synthesis of the rate effects and the contribution of propagating stress waves of them. The rate effects and the contribution of stress waves do not have the same tendency in the variation of magnitude of them with speed of impact or impulsive loadings. Therefore the rate effects, mentioned above, should be obtained by the tests minimized the effect of stress waves (high rate loading test). This paper deals with the testing techniques with high rate loadings and impact, and also reports the main results of these tests. (orig.) [de

Reinforcement function design and bias for efficient learning in mobile robots

International Nuclear Information System (INIS)

Touzet, C.; Santos, J.M.

1998-01-01

The main paradigm in sub-symbolic learning robot domain is the reinforcement learning method. Various techniques have been developed to deal with the memorization/generalization problem, demonstrating the superior ability of artificial neural network implementations. In this paper, the authors address the issue of designing the reinforcement so as to optimize the exploration part of the learning. They also present and summarize works relative to the use of bias intended to achieve the effective synthesis of the desired behavior. Demonstrative experiments involving a self-organizing map implementation of the Q-learning and real mobile robots (Nomad 200 and Khepera) in a task of obstacle avoidance behavior synthesis are described. 3 figs., 5 tabs

Steel fiber reinforced concrete

International Nuclear Information System (INIS)

Baloch, S.U.

2005-01-01

Steel-Fiber Reinforced Concrete is constructed by adding short fibers of small cross-sectional size .to the fresh concrete. These fibers reinforce the concrete in all directions, as they are randomly oriented. The improved mechanical properties of concrete include ductility, impact-resistance, compressive, tensile and flexural strength and abrasion-resistance. These uniqlte properties of the fiber- reinforcement can be exploited to great advantage in concrete structural members containing both conventional bar-reinforcement and steel fibers. The improvements in mechanical properties of cementitious materials resulting from steel-fiber reinforcement depend on the type, geometry, volume fraction and material-properties of fibers, the matrix mix proportions and the fiber-matrix interfacial bond characteristics. Effects of steel fibers on the mechanical properties of concrete have been investigated in this paper through a comprehensive testing-programme, by varying the fiber volume fraction and the aspect-ratio (Lid) of fibers. Significant improvements are observed in compressive, tensile, flexural strength and impact-resistance of concrete, accompanied by marked improvement in ductility. optimum fiber-volume fraction and aspect-ratio of steel fibers is identified. Test results are analyzed in details and relevant conclusions drawn. The research is finally concluded with future research needs. (author)

A Robust Cooperated Control Method with Reinforcement Learning and Adaptive H∞ Control

Science.gov (United States)

Obayashi, Masanao; Uchiyama, Shogo; Kuremoto, Takashi; Kobayashi, Kunikazu

This study proposes a robust cooperated control method combining reinforcement learning with robust control to control the system. A remarkable characteristic of the reinforcement learning is that it doesn't require model formula, however, it doesn't guarantee the stability of the system. On the other hand, robust control system guarantees stability and robustness, however, it requires model formula. We employ both the actor-critic method which is a kind of reinforcement learning with minimal amount of computation to control continuous valued actions and the traditional robust control, that is, H∞ control. The proposed system was compared method with the conventional control method, that is, the actor-critic only used, through the computer simulation of controlling the angle and the position of a crane system, and the simulation result showed the effectiveness of the proposed method.

Corrosion of reinforcement bars in steel ibre reinforced concrete structures

DEFF Research Database (Denmark)

Solgaard, Anders Ole Stubbe

and the influence of steel fibres on initiation and propagation of cracks in concrete. Moreover, the impact of fibres on corrosion-induced cover cracking was covered. The impact of steel fibres on propagation of reinforcement corrosion was investigated through studies of their impact on the electrical resistivity...... of concrete, which is known to affect the corrosion process of embedded reinforcement. The work concerning the impact of steel fibres on initiation and propagation of cracks was linked to corrosion initiation and propagation of embedded reinforcement bars via additional studies. Cracks in the concrete cover...... are known to alter the ingress rate of depassivating substances and thereby influence the corrosion process. The Ph.D. study covered numerical as well as experimental studies. Electrochemically passive steel fibres are electrically isolating thus not changing the electrical resistivity of concrete, whereas...

Advance on Al2O3 Particulates Reinforced Aluminum Metal Matrix Composites (Al-MMCs Manufactured by the Power Metallurgy(PM Methods- Improved PM Techniques

Directory of Open Access Journals (Sweden)

Xu Lina

2016-01-01

Full Text Available Aluminum metal matrix composites (Al-MMCs with Al2O3 particulates as reinforcement fabricated by the power metallurgy (PM methods have gained much attention due to their unique characteristics of the wide range of Al2O3 particles addition, easy-operating process and effectiveness. The improved PM techniques, such as the high energy ball milling, powder extruder and high pressure torsion were applied to further strengthening the properties or/and diminishing the agglomeration of strength particles. The formation of liquid phase assisted densification of compacts to promote the sintering of composites. Complex design of Al2O3 particles with other particles was another efficient method to tailor the properties of Al-MMCs.

Quartz crystal reinforced quartz glass by spark plasma sintering

International Nuclear Information System (INIS)

Torikai, D.; Barazani, B.; Ono, E.; Santos, M.F.M.; Suzuki, C.K.

2011-01-01

The Spark Plasma Sintering presents fast processing time when compared to conventional sintering techniques. This allows to control the grain growth during sintering as well as the diffusion rate of a multi-material compounds, and make possible obtainment of functionally graded materials and nanostructured compounds. Powders of high purity silica glass and crystalline silica were sintered in a SPS equipment at temperatures around 1350° C, i.e., above the softening temperature of silica glass and below the melting temperature of quartz crystal. As a result, glass ceramics with pure silica glass matrix reinforced with crystalline alpha-quartz grains were fabricated at almost any desired range of composition, as well as controlled size of the crystalline reinforcement. X-ray diffraction and density measurements showed the possibility to manufacture a well controlled density and crystallinity glass-ceramic materials. (author)

Effect of STOP technique on safety climate in a construction company.

Science.gov (United States)

Darvishi, Ebrahim; Maleki, Afshin; Dehestaniathar, Saeed; Ebrahemzadih, Mehrzad

2015-01-01

Safety programs are a core part of safety management in workplaces that can reduce incidents and injuries. The aim of this study was to investigate the influence of Safety Training Observation Program (STOP) technique as a behavior modification program on safety climate in a construction company. This cross-sectional study was carried out on workers of the Petrochemical Construction Company, western Iran. In order to improve safety climate, an unsafe behavior modification program entitled STOP was launched among workers of project during 12 months from April 2013 and April 2014. The STOP technique effectiveness in creating a positive safety climate was evaluated using the Safety Climate Assessment Toolkit. 76.78% of total behaviors were unsafe. 54.76% of total unsafe acts/ at-risk behaviors were related to the fall hazard. The most cause of unsafe behaviors was associated with habit and unavailability of safety equipment. After 12 month of continuous implementation the STOP technique, 55.8% of unsafe behaviors reduced among workers. The average score of safety climate evaluated using of the Toolkit, before and after the implementation of the STOP technique was 5.77 and 7.24, respectively. The STOP technique can be considered as effective approach for eliminating at-risk behavior, reinforcing safe work practices, and creating a positive safety climate in order to reduction incidents/injuries.

Algorithms for Reinforcement Learning

CERN Document Server

Szepesvari, Csaba

2010-01-01

Reinforcement learning is a learning paradigm concerned with learning to control a system so as to maximize a numerical performance measure that expresses a long-term objective. What distinguishes reinforcement learning from supervised learning is that only partial feedback is given to the learner about the learner's predictions. Further, the predictions may have long term effects through influencing the future state of the controlled system. Thus, time plays a special role. The goal in reinforcement learning is to develop efficient learning algorithms, as well as to understand the algorithms'

IMPROVEMENT OF FATIGUE STRENGTH OF TIN BABBITT BY REINFORCING WITH NANO ILMENITE

Directory of Open Access Journals (Sweden)

M. V. S. BABU

2017-08-01

Full Text Available Tin Babbitt is an idle journal bearing material, its fatigue strength limits and its usage. To enhance its fatigue strength, in this paper a Tin Babbitt metal matrix is reinforced with nano Ilmenite. The metal matrix nanocomposite was fabricated by using ultrasonic assisted stir casting technique. ASTM standards in statistical planning for fatigue testing were employed in planning the fatigue tests. Fatigue tests were conducted at three stress levels, i.e., 0.9 UTS, 0.7 UTS and 0.5 UTS. Tests were conducted on a rotating-beam type fatigue testing machine. It was observed that the nano Ilmenite reinforcement enhanced the fatigue strength of Tin Babbitt.

Nondestructive evaluation of defects in carbon fiber reinforced polymer (CFRP) composites

Science.gov (United States)

Ngo, Andrew C. Y.; Goh, Henry K. H.; Lin, Karen K.; Liew, W. H.

2017-04-01

Carbon fiber reinforced polymer (CFRP) composites are increasingly used in aerospace applications due to its superior mechanical properties and reduced weight. Adhesive bonding is commonly used to join the composite parts since it is capable of joining incompatible or dissimilar components. However, insufficient adhesive or contamination in the adhesive bonds might occur and pose as threats to the integrity of the plane during service. It is thus important to look for suitable nondestructive testing (NDT) techniques to detect and characterize the sub-surface defects within the CFRP composites. Some of the common NDT techniques include ultrasonic techniques and thermography. In this work, we report the use of the abovementioned techniques for improved interpretation of the results.

Modelling of stiffness and damping change in reinforced concrete structures under seismic actions

International Nuclear Information System (INIS)

Koenig, G.; Oetes, A.

1985-01-01

Restoring force and energy dissipation properties of ductile reinforced concrete structures during seismic excitation are investigated. Interpreting the results of earthquake simulation experiments with large scale reinforced concrete structural members mainly subjected to cyclic bending the various types of the force-deflection response and energy dissipation capability will be identified. Two alternative concepts are suggested for modelling: A rigorous model which considers the numerous deformation and dissipation mechanisms using a step by step algorithm for analysis and a simplified practical model which employs a modified spectrum analysis technique and a simple updating procedure for changing stiffness and damping properties of the members. (orig.)

Beyond the Positive Reinforcement of Aggression: Peers' Acceptance of Aggression Promotes Aggression via External Control Beliefs

Science.gov (United States)

Jung, Janis; Krahé, Barbara; Busching, Robert

2018-01-01

Being surrounded by peers who are accepting of aggression is a significant predictor of the development and persistence of aggression in childhood and adolescence. Whereas past research has focused on social reinforcement mechanisms as the underlying processes, the present longitudinal study analysed the role of external control beliefs as an…

Surface treated polypropylene (PP) fibres for reinforced concrete

Energy Technology Data Exchange (ETDEWEB)

López-Buendía, Angel M., E-mail: buendia@uv.es [AIDICO Technological Institute of Construction, Benjamin Franklin 17, 46380 Paterna, Valencia (Spain); Romero-Sánchez, María Dolores [AIDICO Technological Institute of Construction, Marble Technical Unit, Camí de Castella 4, 03660 Novelda. Alicante (Spain); Climent, Verónica [Lafarge Cementos, Polígono Sepes, Isaac Newton s/n, 46500 Sagunto, Valencia (Spain); Guillem, Celia [AIDICO Technological Institute of Construction, Marble Technical Unit, Camí de Castella 4, 03660 Novelda. Alicante (Spain)

2013-12-15

Surface treatments on a polypropylene (PP) fibre have contributed to the improvement of fibre/concrete adhesion in fibre-reinforced concrete. The treatments to the PP fibre were characterized by contact angle measurements, ATR-IR and XPS to analyse chemical alterations. The surface topography and fibre/concrete interaction were analysed by several microscopic techniques, namely optical petrographic, and scanning electron microscopy. Treatment modified the surface chemistry and topography of the fibre by introducing sodium moieties and created additional fibre surface roughness. Modifications in the fibre surface led to an increase in the adhesion properties between the treated fibres and concrete and an improvement in the mechanical properties of the fibre-reinforced concrete composite as compared to the concrete containing untreated PP fibres. Compatibility with the concrete and increased roughness and mineral surface was also improved by nucleated portlandite and ettringite mineral association anchored on the alkaline PP fibre surface, which is induced during treatment.

Better Care Teams: A Stepwise Skill Reinforcement Model.

Science.gov (United States)

Christopher, Beth-Anne; Grantner, Mary; Coke, Lola A; Wideman, Marilyn; Kwakwa, Francis

2016-06-01

The Building Healthy Urban Communities initiative presents a path for organizations partnering to improve patient outcomes with continuing education (CE) as a key component. Components of the CE initiative included traditional CE delivery formats with an essential element of adaptability and new methods, with rigorous evaluation over time that included evaluation prior to the course, immediately following the CE session, 6 to 8 weeks after the CE session, and then subsequent monthly "testlets." Outcome measures were designed to allow for ongoing adaptation of content, reinforcement of key learning objectives, and use of innovative concordant testing and retrieval practice techniques. The results after 1 year of programming suggest the stepwise skill reinforcement model is effective for learning and is an efficient use of financial and human resources. More important, its design is one that could be adopted at low cost by organizations willing to work in close partnership. J Contin Educ Nurs. 2016;47(6):283-288. Copyright 2016, SLACK Incorporated.

A wireless embedded passive sensor for monitoring the corrosion potential of reinforcing steel

International Nuclear Information System (INIS)

Bhadra, Sharmistha; Thomson, Douglas J; Bridges, Greg E

2013-01-01

Corrosion of reinforcing steel, which results in premature deterioration of reinforced concrete structures, is a worldwide problem. Most corrosion sensing techniques require some type of wired connection between the sensor and monitoring electronics. This causes significant problems in their installation and long-term use. In this paper we describe a new type of passive embeddable wireless sensor that is based on an LC coil resonator where the resonant frequency is changed by the corrosion potential of the reinforcing steel. The resonant frequency can be monitored remotely by an interrogator coil inductively coupled to the sensor coil. The sensor unit comprises an inductive coil connected in parallel with a voltage dependent capacitor (varactor) and a pair of corrosion electrodes consisting of a reinforcing steel sensing electrode and a stainless steel reference electrode. Change of potential difference between the electrodes due to variation of the corrosion potential of the reinforcing steel changes the capacitance of the varactor and shifts the resonant frequency of the sensor. A time-domain gating method was used for the interrogation of the inductively coupled corrosion sensor. Results of an accelerated corrosion test using the sensor indicate that the corrosion potential can be monitored with a resolution of less than 10 mV. The sensor is simple in design and requires no power source, making it an inexpensive option for long-term remote monitoring of the corrosion state of reinforcing steel. (paper)

Just Rewards: Positive Discipline Can Teach Students Self-Respect and Empathy.

Science.gov (United States)

Shandler, Nina

1996-01-01

Describes a teacher's approach to classroom management through positive discipline, using positive reinforcements to teach children positive behaviors. Students who feel affirmed can begin to believe in themselves and begin to take responsibility and build successful relationships. Five steps to positive discipline are outlined. (SLD)

Effect of Sodium bicarbonate on Fire behaviour of tilled E- Glass Reinforced Epoxy Composites

Science.gov (United States)

Girish, S.; Devendra, K.; Bharath, K. N.

2016-09-01

Composites such as fibre reinforced polymers give us the good mechanical properties, but their fire behaviour is not appreciable and needs to be improved. In this work, E- glass fiber is used as a reinforcement material and Epoxy resin is used as a matrix with particulate sodium bi-carbonate (NaHCO3) is used as additive. The hand lay-up technique is adopted for the development of composites by varying percentage of additive. All the tests were conducted according to ASTM standards to study the Fire behaviour of the developed composites. The different fire properties like Ignition time, mass loss rate and flame propagation rate of Fiber Reinforced Polymers (FRP) with NaHCO3 are compared with neat FRPs. It is found that the ignition time increases as the percentage of additive is increased.

Long-fibre reinforced thermoplastics. Applications and limitations of a new type of material

Energy Technology Data Exchange (ETDEWEB)

Neise, E.

1986-06-01

New processing possibilities are offered by long-fibre reinforced thermoplastics, because - contrary to thermoset processing - no chemical reaction occurs and thermoforming and welding of prepregs is possible. Processing techniques like filament winding, tape laying or pultrusion are in development at different institutes.

Linking human factors to corporate strategy with cognitive mapping techniques.

Science.gov (United States)

Village, Judy; Greig, Michael; Salustri, Filippo A; Neumann, W Patrick

2012-01-01

For human factors (HF) to avoid being considered of "side-car" status, it needs to be positioned within the organization in such a way that it affects business strategies and their implementation. Tools are needed to support this effort. This paper explores the feasibility of applying a technique from operational research called cognitive mapping to link HF to corporate strategy. Using a single case study, a cognitive map is drawn to reveal the complex relationships between human factors and achieving an organization's strategic goals. Analysis of the map for central concepts and reinforcing loops enhances understanding that can lead to discrete initiatives to facilitate integration of HF. It is recommended that this technique be used with senior managers to understand the organizations` strategic goals and enhance understanding of the potential for HF to contribute to the strategic goals.

Reinforced concrete behavior due to missile impact

International Nuclear Information System (INIS)

Alderson, M.A.H.G.; Bartley, R.; O'Brien, T.P.

1977-01-01

The assessment of the safety of nuclear reactors has necessitated the study of the effect of missiles on reinforced concrete containment structures. Two simple theoretical calculational methods have been developed to provide basic information. The first is based on a crude energy balance approach in which that part of the kinetic energy of the missile which is transferred into the containment structure, is absorbed only as bending strain energy. To determine the energy transferred into the structure it is assumed that during the loading the target does not respond. The energy input to the structure is thus equal to the kinetic energy it will possess immediately the impulse has been removed. The boundary of the responding zone is defined by the distance travelled by the shear stress wave during the time in which the impact force increases to the load at which the shear capacity reaches the ultimate shear resistance. The second method is based on the equation of motion for an equivalent one-degree-of-freedom system assuming that only the peak value of deflection is important and that damping can be ignored. The spring stiffness of the equivalent system has been based upon the stiffness of the actual disc configuration responding in the flexural mode only. The boundaries of the disc have been defined by using the elastic plate formulae and equating those positive and negative moments which will produce a specified yield line pattern which may be inferred from plastic plate formulae. The equation of motion is solved to indicate how the quantity of reinforcement included in the structure may modify the peak deflection. By limiting the ductility ratio of the reinforcement to some prescribed level it is possible to indicate the quantity of reinforcement w

Modelling reinforcement corrosion in concrete

DEFF Research Database (Denmark)

Michel, Alexander; Geiker, Mette Rica; Stang, Henrik

2012-01-01

A physio-chemical model for the simulation of reinforcement corrosion in concrete struc-tures was developed. The model allows for simulation of initiation and subsequent propaga-tion of reinforcement corrosion. Corrosion is assumed to be initiated once a defined critical chloride threshold......, a numerical example is pre-sented, that illustrates the formation of corrosion cells as well as propagation of corrosion in a reinforced concrete structure....

The Reinforcement Learning Competition 2014

OpenAIRE

Dimitrakakis, Christos; Li, Guangliang; Tziortziotis, Nikoalos

2014-01-01

Reinforcement learning is one of the most general problems in artificial intelligence. It has been used to model problems in automated experiment design, control, economics, game playing, scheduling and telecommunications. The aim of the reinforcement learning competition is to encourage the development of very general learning agents for arbitrary reinforcement learning problems and to provide a test-bed for the unbiased evaluation of algorithms.

Fibre reinforcement in a structurally compromised endodontically treated molar: a case report

Directory of Open Access Journals (Sweden)

Renita Soares

2016-05-01

Full Text Available The reconstruction of structurally compromised posterior teeth is a rather challenging procedure. The tendency of endodontically treated teeth (ETT to fracture is considerably higher than vital teeth. Although posts and core build-ups followed by conventional crowns have been generally employed for the purpose of reconstruction, this procedure entails sacrificing a considerable amount of residual sound enamel and dentin. This has drawn the attention of researchers to fibre reinforcement. Fibre-reinforced composite (FRC, designed to replace dentin, enables the biomimetic restoration of teeth. Besides improving the strength of the restoration, the incorporation of glass fibres into composite resins leads to favorable fracture patterns because the fibre layer acts as a stress breaker and stops crack propagation. The following case report presents a technique for reinforcing a badly broken-down ETT with biomimetic materials and FRC. The proper utilization of FRC in structurally compromised teeth can be considered to be an economical and practical measure that may obviate the use of extensive prosthetic treatment.

Evaluation of mechanical properties of hybrid fiber (hemp, jute, kevlar) reinforced composites

Science.gov (United States)

Suresha, K. V.; Shivanand, H. K.; Amith, A.; Vidyasagar, H. N.

2018-04-01

In today's world composites play wide role in all the engineering fields. The reinforcement of composites decides the properties of the material. Natural fiber composites compared to synthetic fiber possesses poor mechanical properties. The solution for this problem is to use combination of natural fiber and synthetic fiber. Hybridization helps to improve the overall mechanical properties of the material. In this study, hybrid reinforced composites of Hemp fabric/Kevlar fabric/Epoxy and Jute fabric/ Kevlar fabric/Epoxy composites are fabricated using Simple hand layup technique followed by Vacuum bagging process. Appropriate test methods as per standards and guidelines are followed to analyze mechanical behavior of the composites. The mechanical characteristics like tensile, compression and flexural properties of the hybrid reinforced composites are tested as per the ASTM standards by series of tensile test; compression test and three point bending tests were conducted on the hybrid composites. A quantitative relationship between the Hemp fabric/Kevlar fabric/Epoxy and Jute/ Kevlar fabric/Epoxy has been established with constant thickness.

Effect of sintering temperatures on titanium matrix composites reinforced by ceramic particles

Energy Technology Data Exchange (ETDEWEB)

Romero, F.; Amigo, V.; Busquets, D.; Klyatskina, E. [Mechanical and Materials Engineering Department. Polytechnical University of Valencia, Valencia (Spain)

2005-07-01

Titanium and titanium composites have a potential use in aerospace and biotechnology industries, and nowadays in others like sports and fashion ones. In this work composite materials, based on titanium matrix reinforced with ceramic particles, have been developed. PM route is used to obtain compact and sintered samples. TiN and TiAl powders, are milled with Ti powder in different volumetric percentages in a ball mill. These mixtures are pressed in a uniaxial press and sintered in a vacuum furnace at different temperatures between 1180 to 1220 deg. C. Porosity of samples is analysed, before and after the sintering process, by Archimedes technique and by image analysis. Mechanical properties and the reinforcement particles influence in the titanium matrix are studied by flexion test in green and sintered states, and by hardness and microhardness tests. Complimentarily, a microstructural analysis is carried out by optical and electron microscopy, and the reactivity between the reinforce particles and titanium matrix are studied. (authors)

Nonlinear earthquake analysis of reinforced concrete frames with fiber and Bernoulli-Euler beam-column element.

Science.gov (United States)

Karaton, Muhammet

2014-01-01

A beam-column element based on the Euler-Bernoulli beam theory is researched for nonlinear dynamic analysis of reinforced concrete (RC) structural element. Stiffness matrix of this element is obtained by using rigidity method. A solution technique that included nonlinear dynamic substructure procedure is developed for dynamic analyses of RC frames. A predicted-corrected form of the Bossak-α method is applied for dynamic integration scheme. A comparison of experimental data of a RC column element with numerical results, obtained from proposed solution technique, is studied for verification the numerical solutions. Furthermore, nonlinear cyclic analysis results of a portal reinforced concrete frame are achieved for comparing the proposed solution technique with Fibre element, based on flexibility method. However, seismic damage analyses of an 8-story RC frame structure with soft-story are investigated for cases of lumped/distributed mass and load. Damage region, propagation, and intensities according to both approaches are researched.

Steel fiber reinforced concrete pipes: part 1: technological analysis of the mechanical behavior

Directory of Open Access Journals (Sweden)

A. D. de Figueiredo

Full Text Available This paper is the first part of an extensive work focusing the technological development of steel fiber reinforced concrete pipes (FRCP. Here is presented and discussed the experimental campaign focusing the test procedure and the mechanical behavior obtained for each of the dosages of fiber used. In the second part ("Steel fiber reinforced concrete pipes. Part 2: Numerical model to simulate the crushing test", the aspects of FRCP numerical modeling are presented and analyzed using the same experimental results in order to be validated. This study was carried out trying to reduce some uncertainties related to FRCP performance and provide a better condition to the use of these components. In this respect, an experimental study was carried out using sewage concrete pipes in full scale as specimens. The diameter of the specimens was 600 mm, and they had a length of 2500 mm. The pipes were reinforced with traditional bars and different contents of steel fibers in order to compare their performance through the crushing test. Two test procedures were used in that sense. In the 1st Series, the diameter displacement was monitored by the use of two LVDTs positioned at both extremities of the pipes. In the 2nd Series, just one LVDT is positioned at the spigot. The results shown a more rigidity response of the pipe during tests when the displacements were measured at the enlarged section of the socket. The fiber reinforcement was very effective, especially when low level of displacement was imposed to the FRCP. At this condition, the steel fibers showed an equivalent performance to superior class pipes made with traditional reinforced. The fiber content of 40 kg/m3 provided a hardening behavior for the FRCP, and could be considered as equivalent to the critical volume in this condition.

Procrastination in the pigeon: Can conditioned reinforcement increase the likelihood of human procrastination?

Science.gov (United States)

Zentall, Thomas R; Case, Jacob P; Andrews, Danielle M

2017-11-29

Procrastination is the tendency to put off initiation or completion of a task. Although people are typically known to procrastinate, recent research suggests that they sometimes "pre-crastinate" by initiating a task sooner than they need to (Rosenbaum et al. in Psychological Science, 25(7), 1487-1496, 2014). A similar finding of precrastination was reported by Wasserman and Brzykcy (Psychonomic Bulletin & Review, 22, 1130-1134, 2015) with pigeons using a somewhat different procedure. In the present experiment, we used a procedure with pigeons that was more similar to the procedure used by Rosenbaum et al. Pigeons were given a choice between two sequences of events (concurrent chains). Choice of the procrastination chain resulted in color A, which 15-s later would change to color B and 5-s later resulted in reinforcement. Choice of the precrastination chain resulted in color C, which 5-s later would change to color D and 15-s later resulted in reinforcement. Thus, both chains led to reinforcement after 20 s. Results indicated that the pigeons procrastinated. That is, they preferred the 15-5 chain over the 5-15 chain. The results are consistent with Fantino's (Journal of the Experimental Analysis of Behavior, 12, 723-730, 1969) delay reduction theory, which posits that stimuli that signal a reduction in the delay to reinforcement, such as the 5-s stimulus that occurred immediately prior to reinforcement, serve as strong conditioned reinforcers and should be preferred. In support of this theory, the pigeons pecked most at the 5-s stimulus that led immediately to reinforcement, indicating that it had become a strong conditioned reinforcer. The results suggest that delay reduction theory, a theory that emphasizes the attraction to stimuli that predict reinforcement with a short delay, also may contribute to human procrastination behavior because when task completion comes just before the deadline, it may become a stronger conditioned reinforcer than if task completion

Calculation of load-bearing capacity of prestressed reinforced concrete trusses by the finite element method

Science.gov (United States)

Agapov, Vladimir; Golovanov, Roman; Aidemirov, Kurban

2017-10-01

The technique of calculation of prestressed reinforced concrete trusses with taking into account geometrical and physical nonlinearity is considered. As a tool for solving the problem, the finite element method has been chosen. Basic design equations and methods for their solution are given. It is assumed that there are both a prestressed and nonprestressed reinforcement in the bars of the trusses. The prestress is modeled by setting the temperature effect on the reinforcement. The ways of taking into account the physical and geometrical nonlinearity for bars of reinforced concrete trusses are considered. An example of the analysis of a flat truss is given and the behavior of the truss on various stages of its loading up to destruction is analyzed. A program for the analysis of flat and spatial concrete trusses taking into account the nonlinear deformation is developed. The program is adapted to the computational complex PRINS. As a part of this complex it is available to a wide range of engineering, scientific and technical workers

Piezosurgery for the Lingual Split Technique in Lingual Positioned Impacted Mandibular Third Molar Removal

Science.gov (United States)

Ge, Jing; Yang, Chi; Zheng, Jiawei; Qian, Wentao

2016-01-01

Abstract The aim of this study was to evaluate the effect and safety of lingual split technique using piezosurgery for the extraction of lingual positioned impacted mandibular 3rd molars with the goal of proposing a more minimally invasive choice for this common surgery. Eighty-nine consecutive patients with 110 lingual positioned impacted mandibular 3rd molars requiring extraction were performed the lingual split technique using piezosurgery. One sagittal osteotomy line and 2 transverse osteotomy line were designed for lingual and occlusal bone removal. The success rate, operative time, postoperative outcome, and major complications (including nerve injury, mandible fracture, severe hematoma or edema, and severe pyogenic infection) were documented and analyzed. All impacted mandibular 3rd molars were successfully removed (110/110). The average time of operation was 14.6 minutes (ranged from 7 to 28 minutes). One hundred and seven extraction sites (97.3%) were primary healing. Pain, mouth opening, swelling, and PoSSe scores on postoperative 7-day were 0.34 ± 0.63, 3.88 ± 0.66(cm), 2.4 ± 0.2(cm), and 23.7 ± 5.9, respectively. There were 6 cases (5.5%) had lingual nerve disturbance and 3 cases (2.7%) developed inferior alveolar nerve impairment, and achieved full recovery within 2 months by neurotrophic drug treatment. Our study suggested piezosurgery for lingual split technique provided an effective way for the extraction of lingual positioned and deeply impacted mandibular 3rd molar. PMID:27015214

An asymptotic homogenization model for smart 3D grid-reinforced composite structures with generally orthotropic constituents

International Nuclear Information System (INIS)

Hassan, E M; Kalamkarov, A L; Georgiades, A V; Challagulla, K S

2009-01-01

A comprehensive micromechanical model for smart 3D composite structures reinforced with a periodic grid of generally orthotropic cylindrical reinforcements that also exhibit piezoelectric behavior is developed. The original boundary value problem characterizing the piezothermoelastic behavior of these structures is decoupled into a set of three simpler unit cell problems dealing, separately, with the elastic, piezoelectric and thermal expansion characteristics of the smart composite. The technique used is that of asymptotic homogenization and the solution of the unit cell problems permits determination of the effective elastic, piezoelectric and thermal expansion coefficients. The general orthotropy of the constituent materials is very important from the practical viewpoint and makes the analysis much more complicated. Several examples of practical interest are used to illustrate the work including smart 3D composites with cubic and conical embedded grids as well as diagonally reinforced smart structures. It is also shown in this work that in the limiting particular case of 2D grid-reinforced structures with isotropic reinforcements our results converge to earlier published results

Fracture Behavior and Properties of Functionally Graded Fiber-Reinforced Concrete

International Nuclear Information System (INIS)

Roesler, Jeffery; Bordelon, Amanda; Gaedicke, Cristian; Park, Kyoungsoo; Paulino, Glaucio

2008-01-01

In concrete pavements, a single concrete mixture design is selected to resist mechanical loading without attempting to adversely affect the concrete pavement shrinkage, ride quality, or noise attenuation. An alternative approach is to design distinct layers within the concrete pavement surface which have specific functions thus achieving higher performance at a lower cost. The objective of this research was to address the structural benefits of functionally graded concrete materials (FGCM) for rigid pavements by testing and modeling the fracture behavior of different combinations of layered plain and synthetic fiber-reinforced concrete materials. Fracture parameters and the post-peak softening behavior were obtained for each FGCM beam configuration by the three point bending beam test. The peak loads and initial fracture energy between the plain, fiber-reinforced, and FGCM signified similar crack initiation. The total fracture energy indicated improvements in fracture behavior of FGCM relative to full-depth plain concrete. The fracture behavior of FGCM depended on the position of the fiber-reinforced layer relative to the starter notch. The fracture parameters of both fiber-reinforced and plain concrete were embedded into a finite element-based cohesive zone model. The model successfully captured the experimental behavior of the FGCMs and predicted the fracture behavior of proposed FGCM configurations and structures. This integrated approach (testing and modeling) demonstrates the viability of FGCM for designing layered concrete pavements system

Assessing appetitive, aversive, and negative ethanol-mediated reinforcement through an immature rat model.

Science.gov (United States)

Pautassi, Ricardo M; Nizhnikov, Michael E; Spear, Norman E

2009-06-01

The motivational effects of drugs play a key role during the transition from casual use to abuse and dependence. Ethanol reinforcement has been successfully studied through Pavlovian and operant conditioning in adult rats and mice genetically selected for their ready acceptance of ethanol. Another model for studying ethanol reinforcement is the immature (preweanling) rat, which consumes ethanol and exhibits the capacity to process tactile, odor and taste cues and transfer information between different sensorial modalities. This review describes the motivational effects of ethanol in preweanling, heterogeneous non-selected rats. Preweanlings exhibit ethanol-mediated conditioned taste avoidance and conditioned place aversion. Ethanol's appetitive effects, however, are evident when using first- and second-order conditioning and operant procedures. Ethanol also devalues the motivational representation of aversive stimuli, suggesting early negative reinforcement. It seems that preweanlings are highly sensitive not only to the aversive motivational effects of ethanol but also to its positive and negative (anti-anxiety) reinforcement potential. The review underscores the advantages of using a developing rat to evaluate alcohol's motivational effects.

Mate call as reward: Acoustic communication signals can acquire positive reinforcing values during adulthood in female zebra finches (Taeniopygia guttata).

Science.gov (United States)

Hernandez, Alexandra M; Perez, Emilie C; Mulard, Hervé; Mathevon, Nicolas; Vignal, Clémentine

2016-02-01

Social stimuli can have rewarding properties and promote learning. In birds, conspecific vocalizations like song can act as a reinforcer, and specific song variants can acquire particular rewarding values during early life exposure. Here we ask if, during adulthood, an acoustic signal simpler and shorter than song can become a reward for a female songbird because of its particular social value. Using an operant choice apparatus, we showed that female zebra finches display a preferential response toward their mate's calls. This reinforcing value of mate's calls could be involved in the maintenance of the monogamous pair-bond of the zebra finch. (c) 2016 APA, all rights reserved).

Effect of hybrid fiber reinforcement on the cracking process in fiber reinforced cementitious composites

DEFF Research Database (Denmark)

Pereira, Eduardo B.; Fischer, Gregor; Barros, Joaquim A.O.

2012-01-01

The simultaneous use of different types of fibers as reinforcement in cementitious matrix composites is typically motivated by the underlying principle of a multi-scale nature of the cracking processes in fiber reinforced cementitious composites. It has been hypothesized that while undergoing...... tensile deformations in the composite, the fibers with different geometrical and mechanical properties restrain the propagation and further development of cracking at different scales from the micro- to the macro-scale. The optimized design of the fiber reinforcing systems requires the objective...... materials is carried out by assessing directly their tensile stress-crack opening behavior. The efficiency of hybrid fiber reinforcements and the multi-scale nature of cracking processes are discussed based on the experimental results obtained, as well as the micro-mechanisms underlying the contribution...

The impact of reinforcement contingencies on AD/HD: a review and theoretical appraisal.

Science.gov (United States)

Luman, Marjolein; Oosterlaan, Jaap; Sergeant, Joseph A

2005-02-01

One of the core deficits in attention deficit/hyperactivity disorder (AD/HD) is thought to be an aberrant sensitivity to reinforcement, such as reward and response cost. Twenty-two studies (N=1181 children) employing AD/HD and reinforcement contingencies are reviewed from vantage points: task performance, motivation, and psychophysiology. Results indicate that reinforcement contingencies have a positive impact on task performance and levels of motivation for both children with AD/HD and normal controls. There is evidence that the effect related to task performance is somewhat more prominent in AD/HD. There is some evidence that a high intensity of reinforcement is highly effective in AD/HD. Children with AD/HD prefer immediate over delayed reward. From a psychophysiological point of view, children with AD/HD seem less sensitive to reinforcement compared to controls. While comorbid disorders are suggested to be confounders of the dependent variables, many studies do not examine the effect of oppositional defiant disorder (ODD) and conduct disorder (CD). We discuss the implications of the findings for five theoretical frameworks, including the model by, the cognitive-energetic model (CEM), the dual-pathway model and the BIS/BAS model. Results show a discrepancy between the theoretical models and the behavioural findings.

Natural tooth pontic with splinting of periodontally weakened teeth using fiber-reinforced composite resin

Directory of Open Access Journals (Sweden)

Gauri Srinidhi

2014-01-01

Full Text Available Replacement of missing anterior teeth due to periodontal reasons is challenging due to the poor support of abutment teeth. This prevents the use of fixed partial dentures (FPDs. Fiber-reinforced splinting provides a viable alternative to the dentist while choosing a treatment plan in replacing missing anterior teeth in periodontally compromised patients as opposed to conventional modalities like FPDs or removable partial dentures. Replacing missing teeth using either patient′s own tooth or a denture tooth as pontic can be done by splinting adjacent teeth with fiber reinforced composite. The splinting has an additional advantage of stabilizing adjacent mobile teeth. This case report details the case selection, procedure with follow-up of a case where the natural extracted tooth of the patient was used as pontic to replace a missing anterior tooth. The splinting was done with fiber reinforced composite resin. Fiber-reinforced composite resin splinting of patient′s extracted natural tooth is economical, fast, and easy to use chairside technique with the added benefit of periodontal stabilization.

Evaluating the mechanical properties of E-Glass fiber/carbon fiber reinforced interpenetrating polymer networks

Directory of Open Access Journals (Sweden)

G. Suresh

2015-02-01

Full Text Available A series of vinyl ester and polyurethane interpenetrating polymer networks were prepared by changing the component ratios of VER (Vinyl ester and PU (Polyurethane and the polymerization process was confirmed with Fourier Transform infrared spectroscopy. IPN (Inter Penetrating Polymer Network - VER/PU reinforced Glass and carbon fiber composite laminates were made using the Hand lay up technique. The Mechanical properties of the E-glass and carbon fiber specimens were compared from tests including Tensile, Compressive, Flexural, ILSS (Inter Laminar Shear Strength, Impact & Head Deflection Test (HDT. The IPN Reinforced Carbon fiber specimen showed better results in all the tests than E-Glass fibre reinforced IPN laminate with same thickness of the specimen, according to ASTM standards. It was found that the combination of 60%VER and 40%PU IPN exhibits better impact strength and maximum elongation at break, but at the slight expense of mechanical properties such as tensile, compressive, flexural, ILSS properties. The morphology of the unreinforced and reinforced composites was analyzed with help of scanning electron microscopy.

Process monitoring of fibre reinforced composites using optical fibre sensors

Energy Technology Data Exchange (ETDEWEB)

Fernando, G.F.; Degamber, B.

2006-04-15

The deployment of optical fibre based sensor systems for process monitoring of advanced fibre reinforced organic matrix composites is reviewed. The focus is on thermosetting resins and the various optical and spectroscopy-based techniques that can be used to monitor the processing of these materials. Following brief consideration of the manufacturing methods commonly used in the production of thermoset based composites, a discussion is presented on sensor systems that can be used to facilitate real-time chemical process monitoring. Although the focus is on thermosets, the techniques described can be adapted for chemical monitoring of organic species in general. (author)

Reinforcing mechanism of anchors in slopes: a numerical comparison of results of LEM and FEM

Science.gov (United States)

Cai, Fei; Ugai, Keizo

2003-06-01

This paper reports the limitation of the conventional Bishop's simplified method to calculate the safety factor of slopes stabilized with anchors, and proposes a new approach to considering the reinforcing effect of anchors on the safety factor. The reinforcing effect of anchors can be explained using an additional shearing resistance on the slip surface. A three-dimensional shear strength reduction finite element method (SSRFEM), where soil-anchor interactions were simulated by three-dimensional zero-thickness elasto-plastic interface elements, was used to calculate the safety factor of slopes stabilized with anchors to verify the reinforcing mechanism of anchors. The results of SSRFEM were compared with those of the conventional and proposed approaches for Bishop's simplified method for various orientations, positions, and spacings of anchors, and shear strengths of soil-grouted body interfaces. For the safety factor, the proposed approach compared better with SSRFEM than the conventional approach. The additional shearing resistance can explain the influence of the orientation, position, and spacing of anchors, and the shear strength of soil-grouted body interfaces on the safety factor of slopes stabilized with anchors.

Teaching Positioning and Handling Techniques to Public School Personnel through Inservice Training. Brief Report.

Science.gov (United States)

Inge, Katherine J.; Snell, Martha E.

1985-01-01

Two teachers were taught positioning and handling techniques using written task analyses, demonstrations by an occupational therapist, verbal and modeling prompts, corrective feedback, and praise. Training took place in the natural school environment, during school hours, and with students that the teachers taught. A functional relationship…

A Brief Research Review for Improvement Methods the Wettability between Ceramic Reinforcement Particulate and Aluminium Matrix Composites

Science.gov (United States)

Razzaq, Alaa Mohammed; Majid, Dayang Laila Abang Abdul; Ishak, M. R.; B, Uday M.

2017-05-01

The development of new methods for addition fine ceramic powders to Al aluminium alloy melts, which would lead to more uniform distribution and effective incorporation of the reinforcement particles into the aluminium matrix alloy. Recently the materials engineering research has moved to composite materials from monolithic, adapting to the global need for lightweight, low cost, quality, and high performance advanced materials. Among the different methods, stir casting is one of the simplest ways of making aluminium matrix composites. However, it suffers from poor distribution and combination of the reinforcement ceramic particles in the metal matrix. These problems become significantly effect to reduce reinforcement size, more agglomeration and tendency with less wettability for the ceramic particles in the melt process. Many researchers have carried out different studies on the wettability between the metal matrix and dispersion phase, which includes added wettability agents, fluxes, preheating the reinforcement particles, coating the reinforcement particles, and use composting techniques. The enhancement of wettability of ceramic particles by the molten matrix alloy and the reinforcement particles distribution improvement in the solidified matrix is the main objective for many studies that will be discussed in this paper.

Sex differences in snack food reinforcement in response to increasing dietary protein

Science.gov (United States)

BRACKGROUND: Protein is posited to play a dynamic role in energy balance and reward-driven eating behavior. However, little is known about the effect of increasing protein intake on snack food reinforcement. OBJECTIVE: We sought to determine the extent to which increasing dietary protein changes th...

The effect of processing on the mechanical properties of self-reinforced composites

Science.gov (United States)

Hassani, Farzaneh; Martin, Peter J.; Falzon, Brian G.

2018-05-01

Hot-compaction is one of the most common manufacturing methods for creating recyclable all thermoplastic composites. The current work investigates the compaction of highly oriented self-reinforced fabrics with three processing methods to study the effect of pressure and temperature in the tensile mechanical properties of the consolidated laminates. Hot-press, calender roller and vacuum bag technique were adopted to consolidate bi-component polypropylene woven fabrics in a range of pressures and compaction temperatures. Hot-pressed samples exhibited the highest quality of compaction. The modulus of the hot-pressed samples increased with compaction temperature initially due to the improved interlayer bonding and decreased after a maximum at 150°C because of partial melting of the reinforcement phase. The calender roller technique exhibited to have smaller processing temperature window as the pressure is only applied for a short time and the fabrics start to shrink with increasing the processing temperature. The need for constraining the fabrics through the process is therefore found to be paramount. The Vacuum bag results showed this technique to be the least efficient method because of the low compaction pressure. Microscopic images and void content measurement of the consolidated samples further validate the results from tensile testing.

Mechanical characterization of glass fiber (woven roving/chopped strand mat E-glass fiber) reinforced polyester composites

Science.gov (United States)

Bhaskar, V. Vijaya; Srinivas, Kolla

2017-07-01

Polymer reinforced composites have been replacing most of the engineering material and their applications become more and more day by day. Polymer composites have been analyzing from past thirty five years for their betterment for adapting more applications. This paper aims at the mechanical properties of polyester reinforced with glass fiber composites. The glass fiber is reinforced with polyester in two forms viz Woven Rovings (WRG) and Chopped Strand Mat (CSMG) E-glass fibers. The composites are fabricated by hand lay-up technique and the composites are cut as per ASTM Standard sizes for corresponding tests like flexural, compression and impact tests, so that flexural strength, compression strength, impact strength and inter laminar shear stress(ILSS) of polymer matrix composites are analyzed. From the tests and further calculations, the polyester composites reinforced with Chopped Strand Mat glass fiber have shown better performance against flexural load, compression load and impact load than that of Woven Roving glass fiber.

Reinforcement and recovery of timber structures

Directory of Open Access Journals (Sweden)

Antonio Alves Dias

2006-02-01

Full Text Available Preservation of timber structures is a reason for constant concern because their deterioration often involves compromising the historical patrimony, besides endangering the safety of the structure, and consequently, of their users. Many are the examples of churches, residences or other constructions where this manifestation is a fact. The technique of reinforcing structurally endangered pieces with the addition of natural or synthetic fibers, is an alternative that has been researched. In the group of synthetic fibers, fiberglass, carbon and aramid ones are included. On the other hand, it has been frequent in the restoration of old buildings, especially in Europe, the employment of materials that were not available in the past, aiming to achieve structural, acoustic and aesthetic benefits. On an existing timber structure floor, a concrete slab has been carried out, with an appropriate connection system among the parts, constituting the composite timber-concrete structures. This alternative has been considered as extraordinarily viable, because it gathers a series of convenience related with the durability and it presents better mechanic performance than conventional timber structures. In this work, the state-of-the-art of the use of fibers as structural reinforcement and of the timber-concrete composite structures, is presented.

FOAM CONCRETE REINFORCEMENT BY BASALT FIBRES

Directory of Open Access Journals (Sweden)

Zhukov Aleksey Dmitrievich

2012-10-01

Full Text Available The authors demonstrate that the foam concrete performance can be improved by dispersed reinforcement, including methods that involve basalt fibres. They address the results of the foam concrete modeling technology and assess the importance of technology-related parameters. Reinforcement efficiency criteria are also provided in the article. Dispersed reinforcement improves the plasticity of the concrete mix and reduces the settlement crack formation rate. Conventional reinforcement that involves metal laths and rods demonstrates its limited application in the production of concrete used for thermal insulation and structural purposes. Dispersed reinforcement is preferable. This technology contemplates the infusion of fibres into porous mixes. Metal, polymeric, basalt and glass fibres are used as reinforcing components. It has been identified that products reinforced by polypropylene fibres demonstrate substantial abradability and deformability rates even under the influence of minor tensile stresses due to the low adhesion strength of polypropylene in the cement matrix. The objective of the research was to develop the type of polypropylene of D500 grade that would demonstrate the operating properties similar to those of Hebel and Ytong polypropylenes. Dispersed reinforcement was performed by the basalt fibre. This project contemplates an autoclave-free technology to optimize the consumption of electricity. Dispersed reinforcement is aimed at the reduction of the block settlement in the course of hardening at early stages of their operation, the improvement of their strength and other operating properties. Reduction in the humidity rate of the mix is based on the plasticizing properties of fibres, as well as the application of the dry mineralization method. Selection of optimal parameters of the process-related technology was performed with the help of G-BAT-2011 Software, developed at Moscow State University of Civil Engineering. The authors also

The reinforcing value and liking of resistance training and aerobic exercise as predictors of adult's physical activity.

Science.gov (United States)

Flack, Kyle D; Johnson, LuAnn; Roemmich, James N

2017-10-01

Reinforcing value (motivating value) is a stronger predictor than hedonic value (liking) for engaging in drug use, gambling, and eating. The associations of reinforcing value and liking with physical activity of adults have not yet been studied and may depend on the modes of exercise (e.g., aerobic/cardiovascular exercise, resistance training) under consideration. The purpose of this study was to test associations of the reinforcing value and liking of aerobic exercise training (AT) and resistance exercise training (RT) modes of exercise with usual participation in aerobic and resistance exercise in adults. Men (n=38) and women (n=50) were measured for their liking and relative reinforcing value (RRV) of AT and RT, for their usual vigorous physical activity (VPA) participation, and for usual resistance exercise behavior (Yale physical activity questionnaire). The RRV of AT (RRVAT) and liking of AT were correlated, (r=0.22, pvalue for, but not the liking of, a mode of exercise predicted how much an individual engaged in that mode of exercise. RRVAT (p˂0.01) was positively associated with usual VPA. RRVRT (p˂0.01) was positively associated with RT behavior. The hedonic value of AT and of RT were not associated (p>0.30) with VPA or RT behavior. Reinforcing value of a mode of exercise is a stronger predictor than the liking of that mode of exercise for usual amount of participation in the exercise. Published by Elsevier Inc.

Microanalytical investigation of fibre-reinforced ceramic materials

International Nuclear Information System (INIS)

Meier, B.; Grathwohl, G.

1989-01-01

Microanalytical investigations have been made on samples of ceramic fibres (SiC fibres, (Nicalon) C fibre coated with TiN) and fibre-reinforced ceramics (SiC-and glass-matrices). High resolution Auger electron spectroscopy (HRAES), electron probe microanalysis (EPMA) and scanning electron microscopy were employed for these examinations. Analysis was best performed with HRAES on account of its lateral and depth resolution. Some of the problems involved in this technique are discussed e.g. electron beam effects. AES depth profiles of ceramic fibres are reported and compared with the surface analysis of fibres in the composites after being broken in situ. (orig.)

The possibility of using high strength reinforced concrete

International Nuclear Information System (INIS)

Miura, Nobuaki

1991-01-01

There is recently much research about and developments in reinforced concrete using high strength concrete and reinforcement. As a result, some high-rise buildings and nuclear buildings have been constructed with such concrete. Reinforced concrete will be stronger in the future, but there is a limit to its strength defined by the character of the materials and also by the character of the reinforced concrete members made of the concrete and reinforcement. This report describes the merits and demerits of using high strength reinforced concrete. (author)

Accuracy improvement techniques in Precise Point Positioning method using multiple GNSS constellations

Science.gov (United States)

Vasileios Psychas, Dimitrios; Delikaraoglou, Demitris

2016-04-01

The future Global Navigation Satellite Systems (GNSS), including modernized GPS, GLONASS, Galileo and BeiDou, offer three or more signal carriers for civilian use and much more redundant observables. The additional frequencies can significantly improve the capabilities of the traditional geodetic techniques based on GPS signals at two frequencies, especially with regard to the availability, accuracy, interoperability and integrity of high-precision GNSS applications. Furthermore, highly redundant measurements can allow for robust simultaneous estimation of static or mobile user states including more parameters such as real-time tropospheric biases and more reliable ambiguity resolution estimates. This paper presents an investigation and analysis of accuracy improvement techniques in the Precise Point Positioning (PPP) method using signals from the fully operational (GPS and GLONASS), as well as the emerging (Galileo and BeiDou) GNSS systems. The main aim was to determine the improvement in both the positioning accuracy achieved and the time convergence it takes to achieve geodetic-level (10 cm or less) accuracy. To this end, freely available observation data from the recent Multi-GNSS Experiment (MGEX) of the International GNSS Service, as well as the open source program RTKLIB were used. Following a brief background of the PPP technique and the scope of MGEX, the paper outlines the various observational scenarios that were used in order to test various data processing aspects of PPP solutions with multi-frequency, multi-constellation GNSS systems. Results from the processing of multi-GNSS observation data from selected permanent MGEX stations are presented and useful conclusions and recommendations for further research are drawn. As shown, data fusion from GPS, GLONASS, Galileo and BeiDou systems is becoming increasingly significant nowadays resulting in a position accuracy increase (mostly in the less favorable East direction) and a large reduction of convergence

Reinforced concrete wall under hydrogen detonation

International Nuclear Information System (INIS)

Saarenheimo, A.

2000-11-01

The structural integrity of a reinforced concrete wall in the BWR reactor building under hydrogen detonation conditions has been analysed. Of particular interest is whether the containment integrity can be jeopardised by an external hydrogen detonation. The load carrying capacity of a reinforced concrete wall was studied. The detonation pressure loads were estimated with computerised hand calculations assuming a direct initiation of detonation and applying the strong explosion theory. The results can be considered as rough and conservative estimates for the first shock pressure impact induced by a reflecting detonation wave. Structural integrity may be endangered due to slow pressurisation or dynamic impulse loads associated with local detonations. The static pressure following the passage of a shock front may be relatively high, thus this static or slowly decreasing pressure after a detonation may damage the structure severely. The mitigating effects of the opening of a door on pressure history and structural response were also studied. The non-linear behaviour of the wall was studied under detonations corresponding a detonable hydrogen mass of 0.5 kg and 1.428 kg. Non-linear finite element analyses of the reinforced concrete structure were carried out by the ABAQUS/Explicit program. The reinforcement and its non-linear material behaviour and the tensile cracking of concrete were modelled. Reinforcement was defined as layers of uniformly spaced reinforcing bars in shell elements. In these studies the surrounding structures of the non-linearly modelled reinforced concrete wall were modelled using idealised boundary conditions. Especially concrete cracking and yielding of the reinforcement was monitored during the numerical simulation. (au)

Simple technique to achieve a natural position of the head for cone beam computed tomography

NARCIS (Netherlands)

Damstra, Janalt; Fourie, Zacharias; Ren, Yijin

We developed a modified laser level technique to record the natural position of the head in all three planes of space. This is a simple method for use with three-dimensional images and may be valuable in routine craniofacial assessment.

PHYSICAL AND CHEMICAL PRINCIPLES OF REPAIR TECHNOLOGY PERTAINING TO REINFORCED CONCRETE STRUCTURES

Directory of Open Access Journals (Sweden)

S. N. Leonovich

2008-01-01

Full Text Available The paper presents a brief review of new methods for repair of concrete and reinforced concrete products, structures etc. The review demonstrates that the usage of diffusion processes proceeding in the porous materials makes it possible to obtain positive effects while performing  repair works. 

Effect of reinforcement fibers on the collapse potential of clayey sands

Directory of Open Access Journals (Sweden)

Adjabi Souhila

2018-01-01

Full Text Available The collapse of soils under wetting is a major problem in Geotechnical engineering. The erection of structures on these types of soils, located in arid and semi-arid zones, needs careful treatment of these soils. Soil reinforcement techniques have been rapidly increased during these two decades because of their effectiveness in geotechnical engineering. The aim of this experimental work is to investigate the collapsible soil behaviour in order to improve its characteristics. To achieve this goal, Polyethylene fibers, and Sisal fibers were used as Polyethylene fibers content in mass are varied from 0% (unreinforced samples to 15%; and Sisal fibers content from 0.5% to 1%. The fiber reinforcement is combined with other processing procedures such as compaction and the addition of CPA cement to decrease the collapse potential.

Micro/Nanomechanical characterization of multi-walled carbon nanotubes reinforced epoxy composite.

Science.gov (United States)

Cui, Peng; Wang, Xinnan; Tangpong, X W

2012-11-01

In this paper, the mechanical properties of 1 wt.% multi-walled carbon nanotubes (MWCNTs) reinforced epoxy nanocomposites were characterized using a self-designed micro/nano three point bending tester that was on an atomic force microscope (AFM) to in situ observe MWCNTs movement on the sample surface under loading. The migration of an individual MWCNT at the surface of the nanocomposite was tracked to address the nanomechanical reinforcing mechanism of the nanocomposites. Through morphology analysis of the nanocomposite via scanning electron microscopy, AFM, and digital image correlation technique, it was found that the MWCNTs agglomerate and the bundles were the main factors for limiting the bending strength of the composites. The agglomeration/bundle effect was included in the Halpin-Tsai model to account for the elastic modulus of the nanocomposites.

On the weld strength of in situ tape placed reinforcements on weave reinforced structures

NARCIS (Netherlands)

Grouve, Wouter Johannes Bernardus; Warnet, Laurent; Rietman, Bert; Akkerman, Remko

2012-01-01

Unidirectionally reinforced thermoplastic tapes were welded onto woven fabric reinforced laminates using a laser assisted tape placement process. A mandrel peel setup was used to quantify the interfacial fracture toughness between the tape and the laminate as a measure for weld strength. The tape

Reinforcement Learning State-of-the-Art

CERN Document Server

Wiering, Marco

2012-01-01

Reinforcement learning encompasses both a science of adaptive behavior of rational beings in uncertain environments and a computational methodology for finding optimal behaviors for challenging problems in control, optimization and adaptive behavior of intelligent agents. As a field, reinforcement learning has progressed tremendously in the past decade. The main goal of this book is to present an up-to-date series of survey articles on the main contemporary sub-fields of reinforcement learning. This includes surveys on partially observable environments, hierarchical task decompositions, relational knowledge representation and predictive state representations. Furthermore, topics such as transfer, evolutionary methods and continuous spaces in reinforcement learning are surveyed. In addition, several chapters review reinforcement learning methods in robotics, in games, and in computational neuroscience. In total seventeen different subfields are presented by mostly young experts in those areas, and together the...

Masonry arches retrofitted with steel reinforced grout materials: In-situ experimental tests and advanced FE simulations

Science.gov (United States)

Bertolesi, Elisa; Carozzi, Francesca Giulia; Milani, Gabriele; Poggi, Carlo

2017-11-01

The paper presents the results of a series of in-situ tests carried out on two masonry arches, one unreinforced and the other reinforced with SRG (Steel Reinforced Grout). The arches are built adopting a peculiar construction technique using common Italian bricks with dimensions 250 × 120 × 55 mm3 and 10 mm thick mortar joints. One of the two arches has been reinforced with an SRG material constituted by an inox grid embedded into a layer of lime mortar, whereas the second one is maintained unreinforced for comparison purposes. The experimental set-up is designed to apply an eccentric vertical load placed at ¼ of the span in a series of loading and unloading cycles up to the failure. The numerical analyses have been performed using a sophisticated heterogeneous micro-modeling technique, where bricks, mortar joints and the strengthening have been modeled separately. Finally, the numerical outcomes have been comparatively assessed with respect to the experimental results and the crack patterns obtained at the end of the tests, showing a satisfactory agreement in terms of the global behavior of the arches and their collapse mechanisms.

Electrospinning of single wall carbon nanotube reinforced aligned fibrils and yarns

Science.gov (United States)

Lam, Hoa Le

Commercial carbon fibers produced from a polyacrylonitrile (PAN) precursor have reached their performance limit. The approach in this study involves the use of single carbon nanotubes (SWNT) with an ultra-high elastic modulus of approximately ˜1 TPa and tensile strength of ˜37 GPa at a breaking strain of ˜6% to reinforce PAN. In order to translate these extraordinary properties to a higher order structure, the need for a media to carry and assemble the SWNT into continuous fibers or yarns is necessary. Effective translation of properties can only be achieved through uniform distribution of SWNT and their alignment in the fiber axis. This has been one of the major challenges since SWNTs tend to agglomerate due to high van der Waals attraction between tubes. It is the goal of this study to develop dispersion technique(s) for the SWNT and process them into aligned fibers utilizing the electrospinning process. The electrospun nanofibers were then characterized by various techniques such as ESEM, Raman microspectroscopy, HRTEM, and tensile testing. Composite nanofibers containing various contents of SWNT up to 10 wt. % with diameter ranging from 40--300 nm were successfully electrospun through varying the polymer concentration and spinning parameters. The inclusion of SWNTs and their alignment in the fiber axis were confirmed by Raman microspectroscopy, polarized Raman and HRETEM. The failure mechanism of the nanofibers was investigated by HRTEM through fiber surface fracture. A two stage rupture mechanism was observed where crazing initiates at a surface defect followed by SWNTs pulling out of the PAN matrix. Such mechanisms consume energy therefore strengthening and toughening the fibers. Mechanical drawing of the fiber prior to heat treatment induced molecular orientation resulting in oriented graphite layers in the carbonized fibers. This study has established a processing base and characterization techniques to support the design and development of SWNT

Reinforced Conductive Polyaniline-Paper Composites

Directory of Open Access Journals (Sweden)

Jinhua Yan

2015-05-01

Full Text Available A method for direct aniline interfacial polymerization on polyamideamine-epichlorohydrin (PAE-reinforced paper substrate is introduced in this paper. Cellulose-based papers with and without reinforcement were considered. The polyaniline (PANI-paper composites had surface resistivity lower than 100 Ω/sq after more than 3 polymerizations. Their mechanical strength and thermal stability were analyzed by tensile tests and thermogravimetric analysis (TGA. Fourier transform infrared (FTIR results revealed that there was strong interaction between NH groups in aniline monomers and OH groups in fibers, which did not disappear until after 3 polymerizations. Scanning electron microscopy (SEM and field emission (FE SEM images showed morphological differences between composites using reinforced and untreated base papers. Conductive composites made with PAE-reinforced base paper had both good thermal stability and good mechanical strength, with high conductivity and a smaller PANI amount.

Superelastic SMA–FRP composite reinforcement for concrete structures

International Nuclear Information System (INIS)

Wierschem, Nicholas; Andrawes, Bassem

2010-01-01

For many years there has been interest in using fiber-reinforced polymers (FRPs) as reinforcement in concrete structures. Unfortunately, due to their linear elastic behavior, FRP reinforcing bars are never considered for structural damping or dynamic applications. With the aim of improving the ductility and damping capability of concrete structures reinforced with FRP reinforcement, this paper studies the application of SMA–FRP, a relatively novel type of composite reinforced with superelastic shape memory alloy (SMA) wires. The cyclic tensile behavior of SMA–FRP composites are studied experimentally and analytically. Tests of SMA–FRP composite coupons are conducted to determine their constitutive behavior. The experimental results are used to develop and calibrate a uniaxial SMA–FRP analytical model. Parametric and case studies are performed to determine the efficacy of the SMA–FRP reinforcement in concrete structures and the key factors governing its behavior. The results show significant potential for SMA–FRP reinforcement to improve the ductility and damping of concrete structures while still maintaining its elastic characteristic, typical of FRP reinforcement

Determination of the optimal tolerance for MLC positioning in sliding window and VMAT techniques

International Nuclear Information System (INIS)

Hernandez, V.; Abella, R.; Calvo, J. F.; Jurado-Bruggemann, D.; Sancho, I.; Carrasco, P.

2015-01-01

Purpose: Several authors have recommended a 2 mm tolerance for multileaf collimator (MLC) positioning in sliding window treatments. In volumetric modulated arc therapy (VMAT) treatments, however, the optimal tolerance for MLC positioning remains unknown. In this paper, the authors present the results of a multicenter study to determine the optimal tolerance for both techniques. Methods: The procedure used is based on dynalog file analysis. The study was carried out using seven Varian linear accelerators from five different centers. Dynalogs were collected from over 100 000 clinical treatments and in-house software was used to compute the number of tolerance faults as a function of the user-defined tolerance. Thus, the optimal value for this tolerance, defined as the lowest achievable value, was investigated. Results: Dynalog files accurately predict the number of tolerance faults as a function of the tolerance value, especially for low fault incidences. All MLCs behaved similarly and the Millennium120 and the HD120 models yielded comparable results. In sliding window techniques, the number of beams with an incidence of hold-offs >1% rapidly decreases for a tolerance of 1.5 mm. In VMAT techniques, the number of tolerance faults sharply drops for tolerances around 2 mm. For a tolerance of 2.5 mm, less than 0.1% of the VMAT arcs presented tolerance faults. Conclusions: Dynalog analysis provides a feasible method for investigating the optimal tolerance for MLC positioning in dynamic fields. In sliding window treatments, the tolerance of 2 mm was found to be adequate, although it can be reduced to 1.5 mm. In VMAT treatments, the typically used 5 mm tolerance is excessively high. Instead, a tolerance of 2.5 mm is recommended

UV curing silicon-containing epoxy resin and its glass cloth reinforced composites

International Nuclear Information System (INIS)

Yang Guang; Tang Zhuo; Huang Pengcheng

2007-01-01

A UV-curable cationic silicon-containing epoxy resin formulation was developed. The gel conversion of the cured resin after 10-min UV irradiation reached 80% in the presence of 5% diaryliodonium salt photoinitiator and 5.5% polyol chain transfer agent by cationic ring-opening polymerization. The glass cloth-reinforced composites were fabricated with the silicon-containing epoxy resin using the wet lay-up technique and UV irradiation. The mechanical properties of the composites were evaluated. Compared with glass cloth reinforced bisphenol A epoxy resin matrix composites, the silicon-containing epoxy resin matrix composites possessed higher tensile strength and interlayer shear strength which was 158.5MPa and 9.9MPa respectively while other mechanical properties such as flexural property and tensile modulus were similar. (authors)

Learning to trade via direct reinforcement.

Science.gov (United States)

Moody, J; Saffell, M

2001-01-01

We present methods for optimizing portfolios, asset allocations, and trading systems based on direct reinforcement (DR). In this approach, investment decision-making is viewed as a stochastic control problem, and strategies are discovered directly. We present an adaptive algorithm called recurrent reinforcement learning (RRL) for discovering investment policies. The need to build forecasting models is eliminated, and better trading performance is obtained. The direct reinforcement approach differs from dynamic programming and reinforcement algorithms such as TD-learning and Q-learning, which attempt to estimate a value function for the control problem. We find that the RRL direct reinforcement framework enables a simpler problem representation, avoids Bellman's curse of dimensionality and offers compelling advantages in efficiency. We demonstrate how direct reinforcement can be used to optimize risk-adjusted investment returns (including the differential Sharpe ratio), while accounting for the effects of transaction costs. In extensive simulation work using real financial data, we find that our approach based on RRL produces better trading strategies than systems utilizing Q-learning (a value function method). Real-world applications include an intra-daily currency trader and a monthly asset allocation system for the S&P 500 Stock Index and T-Bills.

Enhancement of shear strength and ductility for reinforced concrete wide beams due to web reinforcement

Directory of Open Access Journals (Sweden)

M. Said

2013-12-01

Full Text Available The shear behavior of reinforced concrete wide beams was investigated. The experimental program consisted of nine beams of 29 MPa concrete strength tested with a shear span-depth ratio equal to 3.0. One of the tested beams had no web reinforcement as a control specimen. The flexure mode of failure was secured for all of the specimens to allow for shear mode of failure. The key parameters covered in this investigation are the effect of the existence, spacing, amount and yield stress of the vertical stirrups on the shear capacity and ductility of the tested wide beams. The study shows that the contribution of web reinforcement to the shear capacity is significant and directly proportional to the amount and spacing of the shear reinforcement. The increase in the shear capacity ranged from 32% to 132% for the range of the tested beams compared with the control beam. High grade steel was more effective in the contribution of the shear strength of wide beams. Also, test results demonstrate that the shear reinforcement significantly enhances the ductility of the wide beams. In addition, shear resistances at failure recorded in this study are compared to the analytical strengths calculated according to the current Egyptian Code and the available international codes. The current study highlights the need to include the contribution of shear reinforcement in the Egyptian Code requirements for shear capacity of wide beams.

Energy efficient microwave heating of carbon fibre reinforced plastic; Energieeffiziente Mikrowellentemperierung von kohlenstofffaserverstaerkten Duroplasten

Energy Technology Data Exchange (ETDEWEB)

Danilov, Maksim

2013-07-01

The polymerization of carbon fiber reinforced thermosetting composites (CFRP) is a dull process step with high energy requirements within the production chain. His improvement would affect the economic and ecological balance of the fiber reinforced materials in a positive way. One possible approach investigated here is tempering of raw materials in a microwave oven. In this work the material to be processed - a carbon fiber-reinforced plastic laminate - is being characterized in the microwave field through electromagnetic and thermal parameters. The relationship between its design parameters (fiber orientation and number of layers), the energy levels (reflection, absorption and transmittance) and the thermal process parameters (temperature gradient achievable) will be established. Afterwards, constructive options will be examined and evaluated which are suitable to install a low-loss (both by means of wave reflections and heat losses) industrial process.

Morphology and mechanical behaviour of concretes reinforced by amorphous cast fibres

International Nuclear Information System (INIS)

Redon, Carl

1997-01-01

This research thesis addresses the characterization of the morphology and mechanical behaviour of concretes reinforced by amorphous cast fibres. It first gathers some general characteristics and observations related to the amorphous cast fibre: roughness, failure mode, amorphous structure, X-ray analysis, fire resistance. Experimental methods and techniques developed for morphological analysis and mechanical tests are presented (sample preparation, tensile test, and compression sample) and the use of image automatic analysis techniques is then addressed (void morphology and granulometry analysis, inter-void distance measurement, fibre spatial distribution). The next part reports the study of the mechanical behaviour under axial compression [fr

Static and dynamic experimental study of strengthened reinforced short concrete corbel by using carbon fabrics, crack path in shear zone

Directory of Open Access Journals (Sweden)

I. Ivanova

2015-10-01

Full Text Available The paper presents an experimental analysis of tracking the path of the cracks and crack growth in strengthened or repair reinforced concrete short corbels bonded by carbon fiber fabrics under static and dynamic loads. The reinforced short concrete corbel is a used precast element, for industrial buildings and structures. In fact, their functioning interestingly unconventional is compared to classical beam type elements. Then the effects of bending and shearing are combined in this case. The horizontal reinforced steel is localized to resist to tensile strength induced in bending top and a transversal strength-absorbing contribution. The introduction of carbon fiber composite in the field of Civil Engineering allows to strengthen or repair reinforced concrete structures using adhesive. So the carbon fiber material has many advantages as its low weight, flexibility, easier handling and also interesting physicochemical properties. However maintenance of civil engineering works is to protect them by ensuring better sealing or limiting corrosion. Then strengthening is to repair structures by using bonding technique to compensate their rigidity loss and limit the cracking. This allows to improve their performance and durability. Bonding of composite material in tensile zone of corbel retrieves most tensile stress and allows the structure to extend their load-bearing capacity. The local behavior of the structure is measured by means of the extensometer technique based on electrical strain gauges. This technique allowed to measure strains of steel, carbon fiber fabrics and concrete. The results of this investigation showed that strengthened reinforced concrete corbel bonded by carbon fiber fabrics can improve the ultimate load to twice and stiffens less than a third. The ultimate load, strain and displacement of the specimen are compared to reference experimental model of monotonic and cyclic applied loads. The success of strengthening depends strongly

Fibre Reinforced Polymer Composites as Internal and External Reinforcements for Building Elements

Directory of Open Access Journals (Sweden)

Cătălin Banu

2008-01-01

Full Text Available During the latest decades fibre reinforced polymer (FRP composite materials have proven valuable properties and suitable to be used in construction of new buildings and in upgrading the existing ones. These materials have covered the road from research laboratory and demonstration projects to implementation in actual structures. Nowadays the civil and structural engineering communities are about to commence the stage in which the use of FRP composites is becoming a routine similar to that of traditional material such as concrete, masonry and wood. Two main issues are presented in this paper, the use of FRP composite materials for new structural members (internal reinforcements and strengthening of existing members (externally bonded reinforcements. The advantages and disadvantages as well as the problems and constraints associated with both issues are discussed in detail mainly related to concrete members.

Tank War Using Online Reinforcement Learning

DEFF Research Database (Denmark)

Toftgaard Andersen, Kresten; Zeng, Yifeng; Dahl Christensen, Dennis

2009-01-01

Real-Time Strategy(RTS) games provide a challenging platform to implement online reinforcement learning(RL) techniques in a real application. Computer as one player monitors opponents'(human or other computers) strategies and then updates its own policy using RL methods. In this paper, we propose...... a multi-layer framework for implementing the online RL in a RTS game. The framework significantly reduces the RL computational complexity by decomposing the state space in a hierarchical manner. We implement the RTS game - Tank General, and perform a thorough test on the proposed framework. The results...... show the effectiveness of our proposed framework and shed light on relevant issues on using the RL in RTS games....

Ductility Analysis of RC Beams Considering the Concrete Confinement Effect Produced by the Shear Reinforcement: a Numerical Approach

Directory of Open Access Journals (Sweden)

Caio Gorla Nogueira

Full Text Available Abstract In this paper, a simplified numerical approach to study the influence of the confinement effect provided by transversal reinforcement on the ductility behavior of RC beams in bending is proposed. A unidimensional FEM mechanical model coupled to the Mazars’ damage model to simulate concrete behavior was adopted to assess ductility curvatures at the ultimate limit state. The confinement effect was incorporated to the numerical model through a calibration process of the damage internal parameters, based on the Least Square Method and an analytical law proposed by Kent and Park (1971. Several numerical analyses were carried out considering different designs of RC beams according to a parametric study varying the neutral axis position, concrete compressive strength and the volumetric transversal reinforcement ratio. The obtained results showed the importance of the amount of transversal reinforcement on the ductility behavior, increasing the ductility factor even for the cases with inappropriate neutral axis position.

Nondestructive damage detection and evaluation technique for seismically damaged structures

Science.gov (United States)

Adachi, Yukio; Unjoh, Shigeki; Kondoh, Masuo; Ohsumi, Michio

1999-02-01

The development of quantitative damage detection and evaluation technique, and damage detection technique for invisible damages of structures are required according to the lessons from the 1995 Hyogo-ken Nanbu earthquake. In this study, two quantitative damage sensing techniques for highway bridge structures are proposed. One method is to measure the change of vibration characteristics of the bridge structure. According to the damage detection test for damaged bridge column by shaking table test, this method can successfully detect the vibration characteristic change caused by damage progress due to increment excitations. The other method is to use self-diagnosis intelligent materials. According to the reinforced concrete beam specimen test, the second method can detect the damage by rupture of intelligent sensors, such as optical fiber or carbon fiber reinforced plastic rod.

Strength Characteristics of Reinforced Sandy Soil

OpenAIRE

S. N. Bannikov; Mahamed Al Fayez

2005-01-01

Laboratory tests on determination of reinforced sandy soil strength characteristics (angle of internal friction, specific cohesive force) have been carried out with the help of a specially designed instrument and proposed methodology. Analysis of the obtained results has revealed that cohesive forces are brought about in reinforced sandy soil and an angle of internal soil friction becomes larger in comparison with non-reinforced soil.

Thermoplastic Composites Reinforced with Textile Grids: Development of a Manufacturing Chain and Experimental Characterisation

Science.gov (United States)

Böhm, R.; Hufnagl, E.; Kupfer, R.; Engler, T.; Hausding, J.; Cherif, C.; Hufenbach, W.

2013-12-01

A significant improvement in the properties of plastic components can be achieved by introducing flexible multiaxial textile grids as reinforcement. This reinforcing concept is based on the layerwise bonding of biaxially or multiaxially oriented, completely stretched filaments of high-performance fibers, e.g. glass or carbon, and thermoplastic components, using modified warp knitting techniques. Such pre-consolidated grid-like textiles are particularly suitable for use in injection moulding, since the grid geometry is very robust with respect to flow pressure and temperature on the one hand and possesses an adjustable spacing to enable a complete filling of the mould cavity on the other hand. The development of pre-consolidated textile grids and their further processing into composites form the basis for providing tailored parts with a large number of additional integrated functions like fibrous sensors or electroconductive fibres. Composites reinforced in that way allow new product groups for promising lightweight structures to be opened up in future. The article describes the manufacturing process of this new composite class and their variability regarding reinforcement and function integration. An experimentally based study of the mechanical properties is performed. For this purpose, quasi-static and highly dynamic tensile tests have been carried out as well as impact penetration experiments. The reinforcing potential of the multiaxial grids is demonstrated by means of evaluating drop tower experiments on automotive components. It has been shown that the load-adapted reinforcement enables a significant local or global improvement of the properties of plastic components depending on industrial requirements.

An optimized staining technique for the detection of Gram positive and Gram negative bacteria within tissue.

Science.gov (United States)

Becerra, Sandra C; Roy, Daniel C; Sanchez, Carlos J; Christy, Robert J; Burmeister, David M

2016-04-12

Bacterial infections are a common clinical problem in both acute and chronic wounds. With growing concerns over antibiotic resistance, treatment of bacterial infections should only occur after positive diagnosis. Currently, diagnosis is delayed due to lengthy culturing methods which may also fail to identify the presence of bacteria. While newer costly bacterial identification methods are being explored, a simple and inexpensive diagnostic tool would aid in immediate and accurate treatments for bacterial infections. Histologically, hematoxylin and eosin (H&E) and Gram stains have been employed, but are far from optimal when analyzing tissue samples due to non-specific staining. The goal of the current study was to develop a modification of the Gram stain that enhances the contrast between bacteria and host tissue. A modified Gram stain was developed and tested as an alternative to Gram stain that improves the contrast between Gram positive bacteria, Gram negative bacteria and host tissue. Initially, clinically relevant strains of Pseudomonas aeruginosa and Staphylococcus aureus were visualized in vitro and in biopsies of infected, porcine burns using routine Gram stain, and immunohistochemistry techniques involving bacterial strain-specific fluorescent antibodies as validation tools. H&E and Gram stain of serial biopsy sections were then compared to a modification of the Gram stain incorporating a counterstain that highlights collagen found in tissue. The modified Gram stain clearly identified both Gram positive and Gram negative bacteria, and when compared to H&E or Gram stain alone provided excellent contrast between bacteria and non-viable burn eschar. Moreover, when applied to surgical biopsies from patients that underwent burn debridement this technique was able to clearly detect bacterial morphology within host tissue. We describe a modification of the Gram stain that provides improved contrast of Gram positive and Gram negative microorganisms within host

Analytical, Numerical and Experimental Examination of Reinforced Composites Beams Covered with Carbon Fiber Reinforced Plastic

Science.gov (United States)

Kasimzade, A. A.; Tuhta, S.

2012-03-01

In the article, analytical, numerical (Finite Element Method) and experimental investigation results of beam that was strengthened with fiber reinforced plastic-FRP composite has been given as comparative, the effect of FRP wrapping number to the maximum load and moment capacity has been evaluated depending on this results. Carbon FRP qualitative dependences have been occurred between wrapping number and beam load and moment capacity for repair-strengthen the reinforced concrete beams with carbon fiber. Shown possibilities of application traditional known analysis programs, for the analysis of Carbon Fiber Reinforced Plastic (CFRP) strengthened structures.

Producing Durable Continuously Reinforced Concrete Pavement using Glass-ceramic Coated Reinforcing Steel

Science.gov (United States)

2010-02-01

reinforcement if the enamel is broken  Embedded cement grains hydrate if enamel is cracked to self-heal with the formation of calcium silicate hydrate Goal...Reinforced Concrete Pavement The 600% volume change in the iron to iron oxide formation put the concrete in tension and it cracks an spalls BUILDING...corrodes prematurely and delaminates the pavement  Moisture and chlorides can move through the natural porosity of concrete and the cracks in the

Synthesis and Properties of Carbon Nanotube-Grafted Silica Nanoarchitecture-Reinforced Poly(Lactic Acid

Directory of Open Access Journals (Sweden)

Yao-Wen Hsu

2017-07-01

Full Text Available A novel nanoarchitecture-reinforced poly(lactic acid (PLA nanocomposite was prepared using multi-walled carbon nanotube (MWCNT-grafted silica nanohybrids as reinforcements. MWCNT-grafted silica nanohybrids were synthesized by the generation of silica nanoparticles on the MWCNT surface through the sol-gel technique. This synthetic method involves organo-modified MWCNTs that are dispersed in tetrahydrofuran, which incorporates tetraethoxysilane that undergoes an ultrasonic sol-gel process. Gelation yielded highly dispersed silica on the organo-modified MWCNTs. The structure and properties of the nanohybrids were established using 29Si nuclear magnetic resonance, Raman spectroscopy, wide-angle X-ray diffraction, thermogravimetric analysis, and transmission electron microscopy. The resulting MWCNT nanoarchitectures were covalently assembled into silica nanoparticles, which exhibited specific and controllable morphologies and were used to reinforce biodegradable PLA. The tensile strength and the heat deflection temperature (HDT of the PLA/MWCNT-grafted silica nanocomposites increased when the MWCNT-grafted silica was applied to the PLA matrix; by contrast, the surface resistivity of the PLA/MWCNT-grafted silica nanocomposites appeared to decline as the amount of MWCNT-grafted silica in the PLA matrix increased. Overall, the reinforcement of PLA using MWCNT-grafted silica nanoarchitectures was efficient and improved its mechanical properties, heat resistance, and electrical resistivity.

Constitutive model for reinforced concrete

NARCIS (Netherlands)

Feenstra, P.H.; Borst, de R.

1995-01-01

A numerical model is proposed for reinforced-concrete behavior that combines the commonly accepted ideas from modeling plain concrete, reinforcement, and interaction behavior in a consistent manner. The behavior of plain concrete is govern by fracture-energy-level-based formulation both in tension

Tangible Reinforcers: Bonuses or Bribes?

Science.gov (United States)

O'Leary, K. Daniel; And Others

1972-01-01

Objections to the use of tangible reinforcers, such as prizes, candy, cigarettes, and money, are discussed. Treatment programs using tangible reinforcers are recommended as powerful modifers of behavior to be implemented only after less powerful means of modification have been tried. (Author)

TEACHING SELF-CONTROL WITH QUALITATIVELY DIFFERENT REINFORCERS

OpenAIRE

Passage, Michael; Tincani, Matt; Hantula, Donald A.

2012-01-01

This study examined the effectiveness of using qualitatively different reinforcers to teach self-control to an adolescent boy who had been diagnosed with an intellectual disability. First, he was instructed to engage in an activity without programmed reinforcement. Next, he was instructed to engage in the activity under a two-choice fixed-duration schedule of reinforcement. Finally, he was exposed to self-control training, during which the delay to a more preferred reinforcer was initially sh...

Microstructural analysis and mechanical characterization of aluminum matrix nanocomposites reinforced with uncoated and Cu-coated alumina particles

Energy Technology Data Exchange (ETDEWEB)

Beygi, H., E-mail: hossein.beygi@stu-mail.um.ac.ir; Sajjadi, S.A.; Zebarjad, S.M.

2014-06-01

Aluminum matrix composites used in the aerospace, military and automotive industries are typically fabricated by a stir casting method. However, when nanoparticles are used for reinforcement, fabrication of composite materials by this method leads to the formation of a large number of structural defects. In this study, copper coating of alumina reinforcement particles is investigated as a technique for improving the structure of Al-Al{sub 2}O{sub 3} composites. Microstructural investigations by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersion spectroscopy (EDS) and transmission electron microscopy (TEM) showed that the alumina particles were coated uniformly with copper shells. Copper coating of the reinforcing particles significantly increased their wettability in the molten aluminum alloy, strengthened the matrix-particle interfaces and improved the distribution of reinforcing particles within the matrix. Due to these microstructural improvements, the hardness, compressive strength, yield stress, tensile strength and elongation of the composites were enhanced by copper coating of the alumina particles.

Microstructural analysis and mechanical characterization of aluminum matrix nanocomposites reinforced with uncoated and Cu-coated alumina particles

International Nuclear Information System (INIS)

Beygi, H.; Sajjadi, S.A.; Zebarjad, S.M.

2014-01-01

Aluminum matrix composites used in the aerospace, military and automotive industries are typically fabricated by a stir casting method. However, when nanoparticles are used for reinforcement, fabrication of composite materials by this method leads to the formation of a large number of structural defects. In this study, copper coating of alumina reinforcement particles is investigated as a technique for improving the structure of Al-Al 2 O 3 composites. Microstructural investigations by optical microscopy (OM), scanning electron microscopy (SEM) equipped with energy dispersion spectroscopy (EDS) and transmission electron microscopy (TEM) showed that the alumina particles were coated uniformly with copper shells. Copper coating of the reinforcing particles significantly increased their wettability in the molten aluminum alloy, strengthened the matrix-particle interfaces and improved the distribution of reinforcing particles within the matrix. Due to these microstructural improvements, the hardness, compressive strength, yield stress, tensile strength and elongation of the composites were enhanced by copper coating of the alumina particles

Mechanical Behavior of Steel Fiber-Reinforced Concrete Beams Bonded with External Carbon Fiber Sheets.

Science.gov (United States)

Gribniak, Viktor; Tamulenas, Vytautas; Ng, Pui-Lam; Arnautov, Aleksandr K; Gudonis, Eugenijus; Misiunaite, Ieva

2017-06-17

This study investigates the mechanical behavior of steel fiber-reinforced concrete (SFRC) beams internally reinforced with steel bars and externally bonded with carbon fiber-reinforced polymer (CFRP) sheets fixed by adhesive and hybrid jointing techniques. In particular, attention is paid to the load resistance and failure modes of composite beams. The steel fibers were used to avoiding the rip-off failure of the concrete cover. The CFRP sheets were fixed to the concrete surface by epoxy adhesive as well as combined with various configurations of small-diameter steel pins for mechanical fastening to form a hybrid connection. Such hybrid jointing techniques were found to be particularly advantageous in avoiding brittle debonding failure, by promoting progressive failure within the hybrid joints. The use of CFRP sheets was also effective in suppressing the localization of the discrete cracks. The development of the crack pattern was monitored using the digital image correlation method. As revealed from the image analyses, with an appropriate layout of the steel pins, brittle failure of the concrete-carbon fiber interface could be effectively prevented. Inverse analysis of the moment-curvature diagrams was conducted, and it was found that a simplified tension-stiffening model with a constant residual stress level at 90% of the strength of the SFRC is adequate for numerically simulating the deformation behavior of beams up to the debonding of the CFRP sheets.

Acoustic emission monitoring of concrete columns and beams strengthened with fiber reinforced polymer sheets

Science.gov (United States)

Ma, Gao; Li, Hui; Zhou, Wensong; Xian, Guijun

2012-04-01

Acoustic emission (AE) technique is an effective method in the nondestructive testing (NDT) field of civil engineering. During the last two decades, Fiber reinforced polymer (FRP) has been widely used in repairing and strengthening concrete structures. The damage state of FRP strengthened concrete structures has become an important issue during the service period of the structure and it is a meaningful work to use AE technique as a nondestructive method to assess its damage state. The present study reports AE monitoring results of axial compression tests carried on basalt fiber reinforced polymer (BFRP) confined concrete columns and three-point-bending tests carried on BFRP reinforced concrete beams. AE parameters analysis was firstly utilized to give preliminary results of the concrete fracture process of these specimens. It was found that cumulative AE events can reflect the fracture development trend of both BFRP confined concrete columns and BFRP strengthened concrete beams and AE events had an abrupt increase at the point of BFRP breakage. Then the fracture process of BFRP confined concrete columns and BFRP strengthened concrete beams was studied through RA value-average frequency analysis. The RA value-average frequency tendencies of BFRP confined concrete were found different from that of BFRP strengthened concrete beams. The variation tendency of concrete crack patterns during the loading process was revealed.

Open table-top device positioning technique to reduce small bowel obstruction. Positioning accuracy and impact on conformal radiation therapy techniques; Lochbrettechnik zur Duenndarmschonung. Untersuchungen zur Lagerungsgenauigkeit unter Beruecksichtigung konformierender Bestrahlungstechniken

Energy Technology Data Exchange (ETDEWEB)

Rudat, V. [Abteilung Strahlentherapie, Klinische Radiologie, Universitaetsklinikum Heidelberg (Germany); Flentje, M. [Abteilung Strahlentherapie, Klinische Radiologie, Universitaetsklinikum Heidelberg (Germany); Engenhart, R. [Abteilung Strahlentherapie, Klinische Radiologie, Universitaetsklinikum Heidelberg (Germany); Metzger, M. [Abteilung Strahlentherapie, Klinische Radiologie, Universitaetsklinikum Heidelberg (Germany); Wannenmacher, M. [Abteilung Strahlentherapie, Klinische Radiologie, Universitaetsklinikum Heidelberg (Germany)

1995-08-01

The immobilization error of patients positioned on the opern table-top device in prone prosition as well as the movement of the small bowel out of the pelvis by this positioning technique was determined. The positioning error is of special importance for the 3-dimensional treatment planning for conformal radiotherapy. The positioning error was determined by superposing 106 portal films with the corresponding simultor films from 21 patients with carcinoma of the rectum who received 3D-planned conformal radiotherapy (o-field technique with irregular blocks). The movement of the small bowel out of the pelvis was studied by comparing simulator films after barium swallow in supine and open table-top position as well with 3D-treatment plans of the same patient in both positions in 3 cases. The positioning error along the medio-lateral, dorso-ventral und cranio-caudal axis was 1.4/-0.6/1.8 mm and the standard deviation 4.4/6.8/6.3 mm, respectively. In comparison to the supine position more rotation errors in the sagittal view were observed (37% and 9% respectively) with a media of 5.1 . Six out of 22 patients showed no adhesions of the small bowel and a complete movement out of the tratment field was achieved. 14 out of 16 Patients with adhesions revealed a partial movement of the small bowel out of the treatment field. Comparing 3D-treatment plans in both positions again demonstrated a marked reduction of the irradiated small bowel volume with the use of the open table-top decive. (orig.) [Deutsch] Die Anwendung der Lochbrettechnik sowie konformierender Bestrahlungstechnik laesst eine Verminderung der Duenndarmbelastung bei der Bestrahlung pelviner Tumoren erwarten. Die Lagerungsgenauigkeit der Patienten als wichtiger Gesichtspunkt bei der dreidimensionalen Bestrahlungsplanung wurde bestimmt und die Duenndarmverlagerung aus dem Bestrahlungsfeld bei der Patientenlagerung im Lochbrett untersucht. Saemtliche zu untersuchende Patienten erhielten eine dreidimensional geplante

Non-destructive inspection protocol for reinforced concrete barriers and bridge railings

Energy Technology Data Exchange (ETDEWEB)

Chintakunta, Satish R. [Engineering and Software Consultants, Inc., 14123 Robert Paris Ct., Chantilly, VA 20151 (United States); Boone, Shane D. [Federal Highway Administration, Turner Fairbank Highway Research Center, 6300 Georgetown Pike, McLean, VA 22101 (United States)

2014-02-18

Reinforced concrete highway barriers and bridge railings serve to prevent errant vehicles from departing the travel way at grade separations. Despite the important role that they play in maintaining safety and their ubiquitous nature, barrier inspection rarely moves beyond visual inspection. In August 2008, a tractor-trailer fatally departed William Preston Lane, Jr. Memorial Bridge after it dislodged a section of the bridge barrier. Investigations following the accident identified significant corrosion of the anchor bolts attaching the bridge railing to the bridge deck. As a result of the information gathered during its investigation of the accident, the National Transportation Safety Board (NTSB) made recommendations to the Federal Highway Administration concerning Non-Destructive Evaluation (NDE) of concrete bridge railings. The Center for nondestructive evaluation (NDE) at Turner Fairbank Highway Research Center in McLean, VA is currently evaluating feasibility of using four technologies - ground penetrating radar (GPR), ultrasonic pulse-echo, digital radiography and infrared thermal imaging methods to develop bridge inspection methods that augment visual inspections, offer reliable measurement techniques, and are practical, both in terms of time and cost, for field inspection work. Controlled samples containing predefined corrosion levels in reinforcing steel were embedded at barrier connection points for laboratory testing. All four NDE techniques were used in the initial phase I testing. An inspection protocol for detecting and measuring the corrosion of reinforced steel embedded in the anchorage system will be developed as part of phase II research. The identified technologies shall be further developed for field testing utilizing a structure with a barrier in good condition and a structure with a barrier in poor condition.

Non-destructive inspection protocol for reinforced concrete barriers and bridge railings

Science.gov (United States)

Chintakunta, Satish R.; Boone, Shane D.

2014-02-01

Reinforced concrete highway barriers and bridge railings serve to prevent errant vehicles from departing the travel way at grade separations. Despite the important role that they play in maintaining safety and their ubiquitous nature, barrier inspection rarely moves beyond visual inspection. In August 2008, a tractor-trailer fatally departed William Preston Lane, Jr. Memorial Bridge after it dislodged a section of the bridge barrier. Investigations following the accident identified significant corrosion of the anchor bolts attaching the bridge railing to the bridge deck. As a result of the information gathered during its investigation of the accident, the National Transportation Safety Board (NTSB) made recommendations to the Federal Highway Administration concerning Non-Destructive Evaluation (NDE) of concrete bridge railings. The Center for nondestructive evaluation (NDE) at Turner Fairbank Highway Research Center in McLean, VA is currently evaluating feasibility of using four technologies - ground penetrating radar (GPR), ultrasonic pulse-echo, digital radiography and infrared thermal imaging methods to develop bridge inspection methods that augment visual inspections, offer reliable measurement techniques, and are practical, both in terms of time and cost, for field inspection work. Controlled samples containing predefined corrosion levels in reinforcing steel were embedded at barrier connection points for laboratory testing. All four NDE techniques were used in the initial phase I testing. An inspection protocol for detecting and measuring the corrosion of reinforced steel embedded in the anchorage system will be developed as part of phase II research. The identified technologies shall be further developed for field testing utilizing a structure with a barrier in good condition and a structure with a barrier in poor condition.

PARTIAL REINFORCEMENT (ACQUISITION) EFFECTS WITHIN SUBJECTS.

Science.gov (United States)

AMSEL, A; MACKINNON, J R; RASHOTTE, M E; SURRIDGE, C T

1964-03-01

Acquisition performance of 22 rats in a straight alley runway was examined. The animals were subjected to partial reinforcement when the alley was black (B+/-) and continuous reinforcement when it was white (W+). The results indicated (a) higher terminal performance, for partial as against continuous reinforcement conditions, for starting-time and running-time measures, and (b) lower terminal performance under partial conditions for a goal-entry-time measure. These results confirm within subjects an effect previously demonstrated, in the runway, only in between-groups tests, where one group is run under partial reinforcement and a separate group is run under continuous reinforcement in the presence of the same external stimuli. Differences between the runway situation, employing a discrete-trial procedure and performance measures at three points in the response chain, and the Skinner box situation, used in its free-operant mode with a single performance measure, are discussed in relation to the present findings.

Reinforcement Learning in Repeated Portfolio Decisions

OpenAIRE

Diao, Linan; Rieskamp, Jörg

2011-01-01

How do people make investment decisions when they receive outcome feedback? We examined how well the standard mean-variance model and two reinforcement models predict people's portfolio decisions. The basic reinforcement model predicts a learning process that relies solely on the portfolio's overall return, whereas the proposed extended reinforcement model also takes the risk and covariance of the investments into account. The experimental results illustrate that people reacted sensitively to...

Development of novel Mg–Ni60Nb40 amorphous particle reinforced composites with enhanced hardness and compressive response

International Nuclear Information System (INIS)

Jayalakshmi, S.; Sahu, Shreyasi; Sankaranarayanan, S.; Gupta, Sujasha; Gupta, M.

2014-01-01

Development of amorphous alloy/glassy particle reinforced light metal composites is an emerging research field. In this investigation, we have synthesized and characterized Ni 60 Nb 40 amorphous alloy particle reinforced Mg-composites with varying volume fractions. Microwave-assisted two-directional rapid sintering technique followed by hot extrusion was used to produce these pure Mg-based composites. The structural and mechanical properties of the developed composites were investigated, and are discussed using structure–property relationship. Structural analysis indicated the retention of amorphous structure of the reinforcement in all the composites. It was found that the distribution of the reinforcement was strongly dependent on the volume fraction (V f ). The addition of Ni 60 Nb 40 amorphous alloy particles modified the preferred crystal orientation of Mg, as was observed from X-ray diffraction (XRD) analysis. The composites showed significant improvement in hardness (increment up to 120%) and compressive strength (∼85% increase at 5% V f ). Comparison of mechanical properties of the developed composites with those of conventional Mg-composites having ceramic/metallic reinforcements, highlight the effectiveness of using amorphous particles as promising reinforcement materials. - Highlights: • Novel Mg-composites reinforced with Ni 60 Nb 40 amorphous particles were developed . • Microwave sintering and hot extrusion were used to synthesize the composites. • Reinforcements retained the amorphous structure, and changed Mg-crystal orientation. • Composites showed significant enhancement in hardness and compressive properties. • Performance of developed composites are superior/competitive to conventional MMCs

Responding for sucrose and wheel-running reinforcement: effects of sucrose concentration and wheel-running reinforcer duration.

Science.gov (United States)

Belke, Terry W; Hancock, Stephanie D

2003-03-01

Six male albino rats were placed in running wheels and exposed to a fixed-interval 30-s schedule of lever pressing that produced either a drop of sucrose solution or the opportunity to run for a fixed duration as reinforcers. Each reinforcer type was signaled by a different stimulus. In Experiment 1, the duration of running was held constant at 15 s while the concentration of sucrose solution was varied across values of 0, 2.5. 5, 10, and 15%. As concentration decreased, postreinforcement pause duration increased and local rates decreased in the presence of the stimulus signaling sucrose. Consequently, the difference between responding in the presence of stimuli signaling wheel-running and sucrose reinforcers diminished, and at 2.5%, response functions for the two reinforcers were similar. In Experiment 2, the concentration of sucrose solution was held constant at 15% while the duration of the opportunity to run was first varied across values of 15, 45, and 90 s then subsequently across values of 5, 10, and 15 s. As run duration increased, postreinforcement pause duration in the presence of the wheel-running stimulus increased and local rates increased then decreased. In summary, inhibitory aftereffects of previous reinforcers occurred when both sucrose concentration and run duration varied; changes in responding were attributable to changes in the excitatory value of the stimuli signaling the two reinforcers.

Towards reinforcing telemedicine adoption amongst clinicians in Nigeria.

Science.gov (United States)

Adenuga, Kayode I; Iahad, Noorminshah A; Miskon, Suraya

2017-08-01

Telemedicine systems have been considered as a necessary measure to alleviate the shortfall in skilled medical specialists in developing countries. However, the obvious challenge is whether clinicians are willing to use this technological innovation, which has aided medical practice globally. One factor which has received little academic attention is the provision of suitable encouragement for clinicians to adopt telemedicine, in the form of rewards, motivation or incentives. A further consideration for telemedicine usage in developing countries, especially sub-Saharan Africa and Nigeria in particular, are to the severe shortage of available practising clinicians. The researchers therefore explore the need to positively reinforce the adoption of telemedicine amongst clinicians in Nigeria, and also offer a rationale for this using the UTAUT model. Data were collected using a structured paper-based questionnaire, with 252 physicians and nurses from six government hospitals in Ondo state, Nigeria. The study applied SmartPLS 2.0 for analysis to determine the relationship between six variables. Demographic moderating variables, age, gender and profession, were included. The results indicate that performance expectancy (ptelemedicine systems, as predicted using the extended UTAUT model. Our results showed that the use of telemedicine by clinicians in the Nigerian context is perceived as a dual responsibility which requires suitable reinforcement. In addition, performance expectancy, effort expectancy, facilitating condition and reinforcement determinants are influential factors in the use of telemedicine services for remote-patient clinical diagnosis and management by the Nigerian clinicians. Copyright © 2017. Published by Elsevier B.V.

Graphics and control of the guide tube assembly reinforcement manipulators at Sizewell 'A'

International Nuclear Information System (INIS)

Burden, C.

1996-01-01

A method was devised to reinforce the lower lug welds of the Guide Tube Assemblies (GTA's) at Sizewell 'A'. A six degree of freedom manipulator was designed to place a clamp around the lugs and tighten it. The manipulator was fitted with the three fixed cameras but required another surveillance manipulator positioned in an adjacent standpipe to provide additional views. The need to prepare two standpipes limited the rate at which reinforcements could be made. Therefore an articulated two arm camera manipulator, which could be used on the existing manipulator mast was designed and built. The two manipulators were driven from separate desks and were controlled by the same supervisory computer linked to online graphics. The camera arm joints were driven on preplanned routes using a single joystick because of the complex moves and tight spaces involved. A large number of GTA sites have now been reinforced including a dropped GTA which had to be raised to carry out clamping. (Author)

Rational and Mechanistic Perspectives on Reinforcement Learning

Science.gov (United States)

Chater, Nick

2009-01-01

This special issue describes important recent developments in applying reinforcement learning models to capture neural and cognitive function. But reinforcement learning, as a theoretical framework, can apply at two very different levels of description: "mechanistic" and "rational." Reinforcement learning is often viewed in mechanistic terms--as…

Conditioned Reinforcement Value and Resistance to Change

Science.gov (United States)

Shahan, Timothy A.; Podlesnik, Christopher A.

2008-01-01

Three experiments examined the effects of conditioned reinforcement value and primary reinforcement rate on resistance to change using a multiple schedule of observing-response procedures with pigeons. In the absence of observing responses in both components, unsignaled periods of variable-interval (VI) schedule food reinforcement alternated with…

Survey on Ranging Sensors and Cooperative Techniques for Relative Positioning of Vehicles

Directory of Open Access Journals (Sweden)

Fabian de Ponte Müller

2017-01-01

Full Text Available Future driver assistance systems will rely on accurate, reliable and continuous knowledge on the position of other road participants, including pedestrians, bicycles and other vehicles. The usual approach to tackle this requirement is to use on-board ranging sensors inside the vehicle. Radar, laser scanners or vision-based systems are able to detect objects in their line-of-sight. In contrast to these non-cooperative ranging sensors, cooperative approaches follow a strategy in which other road participants actively support the estimation of the relative position. The limitations of on-board ranging sensors regarding their detection range and angle of view and the facility of blockage can be approached by using a cooperative approach based on vehicle-to-vehicle communication. The fusion of both, cooperative and non-cooperative strategies, seems to offer the largest benefits regarding accuracy, availability and robustness. This survey offers the reader a comprehensive review on different techniques for vehicle relative positioning. The reader will learn the important performance indicators when it comes to relative positioning of vehicles, the different technologies that are both commercially available and currently under research, their expected performance and their intrinsic limitations. Moreover, the latest research in the area of vision-based systems for vehicle detection, as well as the latest work on GNSS-based vehicle localization and vehicular communication for relative positioning of vehicles, are reviewed. The survey also includes the research work on the fusion of cooperative and non-cooperative approaches to increase the reliability and the availability.

Glass FRP reinforcement in rehabilitation of concrete marine infrastructure

International Nuclear Information System (INIS)

Newhook, John P.

2006-01-01

Fiber reinforced polymer (FRP) reinforcements for concrete structures are gaining wide acceptance as a suitable alternative to steel reinforcements. The primary advantage is that they do not suffer corrosion and hence they promise to be more durable in environments where steel reinforced concrete has a limited life span. Concrete wharves and jetties are examples of structures subjected to such harsh environments and represent the general class of marine infrastructure in which glass FRP (GFRP) reinforcement should be used for improved durability and service life. General design considerations which make glass FRP suitable for use in marine concrete rehabilitation projects are discussed. A case study of recent wharf rehabilitation project in Canada is used to reinforce these considerations. The structure consisted of a GFRP reinforced concrete deck panel and steel - GFRP hybrid reinforced concrete pile cap. A design methodology is developed for the hybrid reinforcement design and verified through testing. The results of a field monitoring program are used to establish the satisfactory field performance of the GFRP reinforcement. The design concepts presented in the paper are applicable to many concrete marine components and other structures where steel reinforcement corrosion is a problem. (author)

Multi-physics corrosion modeling for sustainability assessment of steel reinforced high performance fiber reinforced cementitious composites

DEFF Research Database (Denmark)

Lepech, M.; Michel, Alexander; Geiker, Mette

2016-01-01

and widespread depassivation, are the mechanism behind experimental results of HPFRCC steel corrosion studies found in the literature. Such results provide an indication of the fundamental mechanisms by which steel reinforced HPFRCC materials may be more durable than traditional reinforced concrete and other......Using a newly developed multi-physics transport, corrosion, and cracking model, which models these phenomena as a coupled physiochemical processes, the role of HPFRCC crack control and formation in regulating steel reinforcement corrosion is investigated. This model describes transport of water...... and chemical species, the electric potential distribution in the HPFRCC, the electrochemical propagation of steel corrosion, and the role of microcracks in the HPFRCC material. Numerical results show that the reduction in anode and cathode size on the reinforcing steel surface, due to multiple crack formation...

The critical dimensions of the response-reinforcer contingency.

Science.gov (United States)

Williams, B A.

2001-05-03

Two major dimensions of any contingency of reinforcement are the temporal relation between a response and its reinforcer, and the relative frequency of the reinforcer given the response versus when the response has not occurred. Previous data demonstrate that time, per se, is not sufficient to explain the effects of delay-of-reinforcement procedures; needed in addition is some account of the events occurring in the delay interval. Moreover, the effects of the same absolute time values vary greatly across situations, such that any notion of a standard delay-of-reinforcement gradient is simplistic. The effects of reinforcers occurring in the absence of a response depend critically upon the stimulus conditions paired with those reinforcers, in much the same manner as has been shown with Pavlovian contingency effects. However, it is unclear whether the underlying basis of such effects is response competition or changes in the calculus of causation.