Dynamic repair priority for a transfer line with a finite buffer

We formulate a continuous-time Markov chain model of a transfer line in which there are two unreliable machines separated by a finite buffer. Due to limited repair resources, simultaneous repairs are not possible in cases where both machines fail, and therefore we develop a repair priority rule that depends on the number of work-pieces present in the buffer. Each machine is characterized by three exponentially distributed random variables: processing time, time to failure, and time to repair. We provide a stochastic model for finding an optimal repair priority rule and an efficient algorithm accompanied by easy-to-use Matlab software. An extensive numerical study is performed to test the sensitivity of the proposed dynamic repair priority rule. While in previous studies repair priority was given to the bottleneck machine, we show that there are situations in which priority should be given to the non-bottleneck machine. Finally, we identify conditions in which adding a second technician is economically advisable.     

Multi-sensor task allocation framework for supply networks security using task administration protocols

This research proposes a multi-sensor task allocation framework for security of supply networks aimed to maximise the number of correctly detected and reported security events (defined as tasks). The framework includes a double layer system consisting of a process layer and a monitoring layer. The process layer allocates sensors to tasks using an ant colony algorithm. The monitoring layer applies four task administration protocols (TAPs) specially developed and implemented to deal with high time-consuming tasks, conflicts in task priorities and sensor failure, defined in this research as overloading, deception and tampering of sensors, respectively. A system objective function for sensor to task allocation was developed to allow computation of the expected value of system performance given the sensor and the task parameters. Sensory limitations evaluated including reliability, distance coverage and the limited number of sensors are addressed in the decision-making process. The framework enables detection of tasks as soon as they occur in every location along the supply network, based on the sensor network distribution. The dual layer system analyses reveal that TAPs increase the systems performance in the scenarios of deception, tampering and overloading by more than 64% with respect to the number of unallocated tasks in comparison to a single layer system. Overall availability was analysed using Monte Carlo simulation and the fault tolerant system yielded significantly increased number of treated tasks (by 11%, p = 0.02).     

Chemiluminescent optical fiber immunosensor detection of Brucella cells presenting smooth-A antigen

Brucellosis is a worldwide distributed zoonotic re-emerging disease, causing abortions in domesticated animals and Malta fever in humans. Currently, the gold standard for confirmation of the existence of the causative agent genus Brucella is the isolation of the bacteria from body or liquid samples, whereas standard serological tests are used for diagnosis. The need for a rapid point of care identification of Brucella organisms has led us to develop a novel chemiluminescent optical fiber immunosensor. The immunosensor based on a conventional enzyme linked immunoassay (ELISA) technique was implemented on optical fibers and its performance was compared to the standard ELISA method. We show that depending on the detecting antibodies used specificity of the assay is achieved. Brucella cells presenting smooth-A O-chain determinant were detected at a minimal protein concentration of 1.098 ng/ml, correlating to 305 cfu/ml, while smooth-M O-chain cells, rough cells and two gram-negative bacteria other than Brucella sp. produced negative results, confirming the high specificity of the technique.     

Nonchronological video synopsis and indexing

The amount of captured video is growing with the increased numbers of video cameras, especially the increase of millions of surveillance cameras that operate 24 hours a day. Since video browsing and retrieval is time consuming, most captured video is never watched or examined. Video synopsis is an effective tool for browsing and indexing of such a video. It provides a short video representation, while preserving the essential activities of the original video. The activity in the video is condensed into a shorter period by simultaneously showing multiple activities, even when they originally occurred at different times. The synopsis video is also an index into the original video by pointing to the original time of each activity. Video Synopsis can be applied to create a synopsis of an endless video streams, as generated by webcams and by surveillance cameras. It can address queries like "Show in one minute the synopsis of this camera broadcast during the past day'. This process includes two major phases: (i) An online conversion of the endless video stream into a database of objects and activities (rather than frames). (ii) A response phase, generating the video synopsis as a response to the user's query.     

Factors Influencing Perceived Benefits and User Satisfaction in Knowledge Management Systems

This study offers a model for predicting users’ perceived benefits and user satisfaction in organizational knowledge management systems. Four constructs are theorized to influence the dependent variables: system quality, knowledge quality, user IS competence, and organizational attitude to knowledge management. The model was empirically tested among 100 respondents working in the knowledge-intensive software industry. The results suggest that knowledge management systems hold certain characteristics to be considered when evaluating technical and socio-psychological factors of users’ perceptions and attitudes toward the systems.     

Levels of consumers’ agency and capacity as predictors for electricity demand reduction in the residential sector

A field study of 50 households in a collective community in Israel provides initial support for the hypotheses about the relations between actors’ agency, capacity and electricity demand reduction. ‘Agency’ refers to actors’ willingness and ability to make their own free choices and ‘capacity’ refers to actors’ ability to perform the choices they made. According to the hypotheses, change is more likely to happen when actors’ levels of agency and capacity are high; unlikely to happen when the levels are low and uncertain when there is a mismatch between levels of agency and capacity (one is high and the other low). In the research, levels of agency and capacity regarding 11 energy saving actions were self-reported and electricity consumption was metered before and during energy saving campaign. Findings show that levels of agency were lower than those of capacity for no-cost actions which require high engagement, while levels of capacity were lower than those of agency for high-cost action which require low engagement. In addition, households with high agency and high capacity reduced their electricity consumption by 9.39 % (on average); those with low agency and low capacity increased their consumption by 6.67 %; and those with a mismatch between agency and capacity reduced their consumption by 1.91 %.     

Enhanced removal of humic acid from water by micelle-montmorillonite composites: Comparison to granulated activated carbon

Removal of humic acid (HA) from water by octadecyltrimethyl-ammonium (ODTMA) micelle–montmorillonite (MMT) composites and by granulated activated carbon (GAC) was studied in dispersion and by filtration. FTIR measurements emphasized that the ODTMA micelle–clay-mineral composite differs from the ODTMA monomer-clay-mineral one. HA adsorption by GAC in dispersion was moderately reduced from 100% initially to 75% with an increase in HA concentrations. In contrast, the fractions adsorbed by the composite increased monotonically with HA concentrations from very low adsorption up to 80%. This effect was explained by the presence of a small concentration of ODTMA monomers in dispersion, which adsorbed on the negatively charged HA and partially neutralized it, or caused charge reversal, which in turn inhibited HA adsorption by the positively charged composite. This effect was verified by mobility measurements and was found to be more pronounced at low HA concentrations. This trend of increase in HA removal with an increase in HA concentration (3 and 10 ppm) was also observed in filtration (50% and 85% removal, respectively), when employing columns of the composite mixed with sand (to improve flow). Throughout the experiment the removal of high HA concentration (10 ppm) by the composite filter remained ~ 80% whereas, the removal by the GAC filter decreased from an initial 80% removal to a complete recovery of the HA (no removal) after the passage of 20 L (200 pore volumes). Upon applying sand of higher quality in the columns the removal of low HA concentrations was nearly complete by the composite column while the GAC only slightly contributed to its removal (for a passage of 100 L (1000 pore volumes)).     

Physical Activity and Psychological Well-Being in Advanced Age: A Meta-Analysis of Intervention Studies.

A meta-analysis examined data from 36 studies linking physical activity to well-being in older adults without clinical disorders. The weighted mean-change effect size for treatment groups (dC. = 0.24) was almost 3 times the mean for control groups (dC. = 0.09). Aerobic training was most beneficial (dC. = 0.29), and moderate intensity activity was the most beneficial activity level (dC. = 0.34). Longer exercise duration was less beneficial for several types of well-being, though findings are inconclusive. Physical activity had the strongest effects on self-efficacy (dC.= 0.38), and improvements in cardiovascular status, strength, and functional capacity were linked to well-being improvement overall. Social-cognitive theory is used to explain the effect of physical activity on well-being. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Complexation with starch for encapsulation and controlled release of menthone and menthol

A platform of starch complexes for the oral release of aroma substances by salivary fluids was studied. Menthone, menthol and limonene were used as model flavor compounds for complexation with starches with different amylose content. Complexes were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC), dynamic light scattering (DLS), and atomic force microscopy (AFM). Aroma retention was tested under pH, temperature and storage challenges. Furthermore, the kinetic of aroma release in simulated saliva fluids (SSF) was also tested. Both menthone and menthol form V-amylose complexes in a ’food grade’ process while limonene does not form such complexes efficiently. Complexation yield was higher, with more included aroma and less free core content, as the amylose content increased. The complexes had melting temperature of over 90 °C. Digestion results suggest that the complexes can release the aroma in the oral cavity.     

Serum creatinine detection by a conducting-polymer-based electrochemical sensor to identify allograft dysfunction

Kidney transplant recipients who have abnormally high creatinine levels in their blood often have allograft dysfunction secondary to rejection. Creatinine has become the preferred marker for renal dysfunction and is readily available in hospital clinical settings. We developed a rapid and accurate polymer-based electrochemical point-of-care (POC) assay for creatinine detection from whole blood to identify allograft dysfunction. The creatinine concentrations of 19 blood samples from transplant recipients were measured directly from clinical serum samples by the conducting polymer-based electrochemical (EC) sensor arrays. These measurements were compared to the traditional clinical laboratory assay. The time required for detection was <5 min from sample loading. Sensitivity of the detection was found to be 0.46 mg/dL of creatinine with only 40 μL sample in the creatinine concentration range of 0 mg/dL to 11.33 mg/dL. Signal levels that were detected electrochemically correlated closely with the creatinine blood concentration detected by the UCLA Ronald Reagan Medical Center traditional clinical laboratory assay (correlation coefficient = 0.94). This work is encouraging for the development of a rapid and accurate POC device for measuring creatinine levels in whole blood.