Improving process models by discovering decision points

Workflow management systems (WfMS) are widely used by business enterprises as tools for administrating, automating and scheduling the business process activities with the available resources. Since the control flow specifications of workflows are manually designed, they entail assumptions and errors, leading to inaccurate workflow models. Decision points, the XOR nodes in a workflow graph model, determine the path chosen toward completion of any process invocation. In this work, we show that positioning the decision points at their earliest points can improve process efficiency by decreasing their uncertainties and identifying redundant activities. We present novel techniques to discover the earliest positions by analyzing workflow logs and to transform the model graph. The experimental results show that the transformed model is more efficient with respect to its average execution time and uncertainty, when compared to the original model.     

Quick and reliable estimation of BOD load of beverage industrial wastewater by developing BOD biosensor

An amperometric biosensor for determination of biochemical oxygen demand in wastewater has been developed to overcome the time consuming monitoring procedures. The performance and stability of the immobilized membrane have been investigated at 37 °C and pH 6.8. Immobilized microbial membranes maintain their stability and activity after intermittent use for 400 cycles when stored at 4 °C in sodium phosphate buffer pH 6.8. The response time of the BOD sensor was only 90 min, being independent of the concentration, and the lower detection limit was 1 mg/l. The obtained BOD values showed correlation with that of the conventional method for BOD determination (BOD5) with a deviation of ±10%. Moreover, the sensor exhibits good repeatability (3.39–4.45%) and reproducibility (1.85–2.25%). Software was added to upgrade this sensor and to make it a promising candidate for online monitoring.     

The effects of noise on frequency-domain parameter estimation ofsynchronous machine models

The authors present results of a study conducted to evaluate the effects of measurement noise on the estimation of machine parameters from standstill frequency response test data. Results obtained indicate that, because the test data are inherently noise-corrupted, multiple solution sets can be obtained. Moreover, some of the estimated machine parameters could be unrealistic. It is shown that the results are very sensitive to the value of armature resistance used in the data analysis. Even a 0.5% error in the value of armature resistance could result in unrealistic estimation of the machine parameters     

The Effect of Nanoparticle Shape on the Photocarrier Dynamics and Photovoltaic Device Performance of Poly(3‐hexylthiophene):CdSe Nanoparticle Bulk Heterojunction Solar Cells

The charge separation and transport dynamics in CdSe nanoparticle:poly(3‐hexylthiophene) (P3HT) blends are reported as a function of the shape of the CdSe‐nanoparticle electron acceptor (dot, rod, and tetrapod). For optimization of organic photovoltaic device performance it is crucial to understand the role of various nanostructures in the generation and transport of charge carriers. The sample processing conditions are carefully controlled to eliminate any processing‐related effects on the carrier generation and on device performance with the aim of keeping the conjugated polymer phase constant and only varying the shape of the inorganic nanoparticle acceptor phase. The electrodeless, flash photolysis time‐resolved microwave conductivity (FP‐TRMC) technique is used and the results are compared to the efficiency of photovoltaic devices that incorporate the same active layer. It is observed that in nanorods and tetrapods blended with P3HT, the high aspect ratios provide a pathway for the electrons to move away from the dissociation site even in the absence of an applied electric field, resulting in enhanced carrier lifetimes that correlate to increased efficiencies in devices. The processing conditions that yield optimum performance in high aspect ratio CdSe nanoparticles blended with P3HT result in poorly performing quantum dot CdSe:P3HT devices, indicating that the latter devices are inherently limited by the absence of the dimensionality that allows for efficient, prolonged charge separation at the polymer:CdSe interface.     

Solar assisted biogas plants III: Energy balance of fixed dome biogas plants and enhancement of production in winters

This paper presents a thermal model of a fixed dome biogas plant, with or without hot charging and having the ground surface above the plant, blackened and glazed. The rate of energy transfer, between the ground and the plant has been determined by electrical simulation experiments, using a small scale model of the plant (made of copper), suspended in copper sulphate solution. For hot charging a shallow solar pond, built on the ground has been considered. The monthly variation of the slurry temperature, corresponding to 1, 4, 8, 15 and 30 m³ plants have been evaluated for Madras, New Delhi and Srinagar, which correspond to typical hot, composite and cold climates; the following cases have been considered:

• 1 Bare plant, without hot charging and blackening/glazing of the ground, above the plant.
• 2 Plant, charged with hot slurry from a shallow solar pond.
• 3 Plant, with ground above blackened and glazed.
• 4 Plant, with ground above blackened and double glazed and also provision for heating the slurry by burning a part of the produced biogas.

It is seen that blackening and single glazing of the ground above the plant is able to maintain the slurry temperature between 28 and 35°C throughout the year in composite climate such as Delhi; in cold climates even double glazing alone is not enough for that purpose. Hot charging from a shallow solar pond alone is not sufficient to maintain satisfactory slurry temperatures in winters of Delhi and of course Srinagar. In hot climates the slurry temperature is sufficiently high, except for a couple of months, when either hot charging from a shallow solar pond or blackening/glazing of the ground above is sufficient to have the slurry temperature in the desirable range. In cold climates such as Srinagar, the desired slurry temperatures can be maintained if a part of the gas produced is burnt for heating the slurry, in addition to blackening and double glazing of the ground above the dome. Theoretical predictions of slurry temperatures have been compared with the field data recorded for an 8 m³ digester at the Energy Complex, Masoodpur, Delhi; the agreement is satisfactory.     

Localized corrosion studies on materials proposed for a safety-grade sodium-to- air decay-heat removal system for fast breeder reactors

The present investigation was carried out to assess the localized corrosion resistance of materials proposed for the construction of the safety-grade sodium-to-air decay-heat removal system for fast breeder reactors. The materials, such as Alloy 800,9Cr-lMo steel, and type 316LN stainless steel, in different microstructural conditions were assessed for pitting and stress-corrosion cracking resistances in a chloride medium. The results indicated that 9Cr-lMo steel in the normalized and tempered condition can be considered for the above application from the standpoint of corrosion resistance.     

Sj?gren''s syndrome presenting with a minor salivary gland mass

To survey the frequency of Lyme borreliosis (LB) and to evaluate its clinical presentation in Europe, we performed a questionnaire interview of a sample of physicians involved in the care of patients with LB. Reference laboratories in 15 European countries agreed to participate by distributing questionnaires to those clinicians who most frequently requested LB serology for their patients. The mean number of cases of LB per physician per country showed a longitudinal geographical gradient, with a higher number of patients seen in Eastern and Central Europe than in Western Europe. Skin involvement was seen in 58.9% of the patients, neurological involvement in 34.3%, joint involvement in 15.4% and cardiac involvement in 2%. About 30% of the patients had multisystem involvement. The frequency of the different manifestations varied greatly between countries. The frequency of diagnosis of LB and the number of serological tests requested were inversely correlated.