Cassava starch functional properties by etherification – hydroxypropylation

Starches are important food biopolymers with gelling properties that are well explored by the food industry for texture and physical food characteristic control. Brazil contributes to a large part of the starches produced world wide, but the modified starches used are imported and expensive. The objective of this work was to develop a hydroxypropylated starch from cassava starch, at a lower price and in conditions in accordance with Brazilian reality. Dihydroxypropylstarch (DHPS) was produced with a less expensive and less harmful substituting molecule, chloropropylene glycol. DHPS physical chemistry properties, retrogradation and micro structural characteristics were studied and compared with native corn, cassava starches and a commercial hydroxypropylated (HPS) cassava starch, with an extensive use in the food industry. DHPS showed the highest values for swelling power and viscosity, low retrogradation and higher freezing–thawing stability, compared with HPS, cassava and native corn starches. The microstructure of DHPS remained unmodified when compared with commercial HPS. Retrogradation and physical chemistry properties are superior to DHPS, which would indicate its use in industrial food production.     

Computational fretting fatigue maps for different plasticity models

This paper presents qualitative elastoplastic simulations and analyses of fretting fatigue. Three hardening constitutive models are considered, and their effects on stick–slip conditions and lifetime prediction are compared. The computational analysis consists of the estimation of the shakedown limit cycle and the fatigue prediction using Dang Van or Crossland criterion. A particular configuration, the interaction of a flat pad with rounded corners in contact with a flat substrate made, respectively, of Inconel In718 and Titanium Ti64 alloys, is studied. The shakedown state is analysed using the cyclic and ratcheting equivalent strain concepts already discussed in the literature. In the paper, different fretting maps, based on slip, shakedown and fatigue regimes, are numerically produced and analysed. A new variable, the global slip percentage, is proposed for the characterization of the stick–slip regimes. Analyses of a series of slip maps show that the different hardening models do not introduce significant changes in the stick–slip conditions. Using finite element method simulations combined with fatigue limit criteria (Dang Van and Crossland), fretting fatigue maps are qualitatively reproduced. The main contribution of this work is a comparative discussion on the influence of the hardening models complexity on such maps.     

"Objective and subjective work monotony: Effects on job satisfaction, psychological distress, and absenteeism in blue-collar workers": Correction.

Reports an error in the original article by S. Melamed et al (Journal of Applied Psychology, 1995[Feb], Vol 80[1], 29–42). The last two numerical entries in the Long-cycle RW vs. VW row in Table 3 were incorrect. The corrected table, which also includes a clarification to Footnote a, is presented. (The following abstract of this article originally appeared in record 1995-23399-001). The relation of objective work conditions (work underload, repetitive or varied work) and subjective monotony to job satisfaction, psychological distress, and sickness absence was examined in 1,278 male and female workers. Subjective monotony was moderately related to the objective work conditions. Hierarchical regression analyses showed that the effects on all outcomes were partially mediated by subjective monotony and were also directly related to repetitive work and work underload. Job satisfaction and psychological distress were mainly related to subjective monotony, whereas sickness absence was equally related to the work conditions and subjective monotony. The highest impact was observed for short-cycle repetitive work. Testing sex interactions revealed that sickness absence was related to the work conditions in women but not in men… (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Compromises between form and function in grid-connected,building-integrated photovoltaics (BIPV) at low-latitude sites

The integration of photovoltaic (PV) modules on building façades and rooftops is an ideal application of solar electricity generators in the urban environment. Maximum annual performance of grid-connected PV is usually obtained with modules tilted at an angle equal to the site latitude, facing the equator. The performance of PV systems not tilted and oriented ideally can drop considerably, depending on site latitude. With grid parity – when the cost of solar electricity becomes competitive with conventional electricity – expected in many countries in the present decade, a more widespread application of PV on buildings is expected, and in this context the main goal of this paper is to demonstrate that good compromises between form and function are possible. In this work we compare the annual energy generation of a curved BIPV system installed as a car port rooftop, with an ideally-oriented and tilted, flat BIPV system installed as a building’s rooftop cover at a low-latitude site (27°S). For the one-year period analysed, the curved-shape BIPV system annual yield was 12% lower than that of the reference BIPV system, and during the summer months (November to February), the curved BIPV installation presented a higher energy yield than the latitude-tilted generator. With these results we show that a good compromise can be reached between form and function in BIPV systems.     

CMOS prototype vision chip with digital pixel structure for grey level image segmentation by means of thresholding and time multiplexing

In this article, a CMOS prototype vision chip with digital pixel structure for grey level image segmentation by means of thresholding and time multiplexing is presented. This approach splits scenes into m frames (one frame per grey level interval). One advantage about this design is that an analogue to digital converter is not required. Moreover, image acquisition and segmentation are performed at the same time by pixels that work simultaneously with each other. The performance from each pixel deals with a maximum quantum efficiency of 0.65, pixel size of 132 μm × 176 μm, fill factor of 0.78%, dark current of 15 mV/s, power dissipation per frame of 341 μW, minimum exposure time of 28.6 μs, maximum exposure time of 1.9 ms, random noise of 3 mV, optical dynamic range of 51 dB and majority of cells with 0–3% of mismatch. Scene decomposition into 256 images occurs in 30.5 ms with white illumination of 650 Lx.     

Thermoeconomic assessment of an absorption refrigeration and hydrogen-fueled diesel power generator cogeneration system

The thermoeconomic assessment of a cogeneration application that uses a reciprocating diesel engine and an ammonia–water absorption refrigeration system for electrical power and cold production from hydrogen as fuel is presented. The purpose of the assessment is to get both exergetic and exergoeconomic costs of the cogeneration plant products at different load conditions and concentrations of hydrogen–diesel oil blends. The exhaust gas of the reciprocating diesel engine is used as an energy source for an ammonia–water absorption refrigeration system. The reciprocating diesel engine was simulated using the Gate Cycle™ software, and the ammonia–water absorption refrigeration system simulation and the thermoeconomic assessment were carried out using the Engineering Equation Solver software (EES). The results show that engine combustion is the process of higher exergy destruction in the cogeneration system. Increased hydrogen concentration in the fuel increases the system exergetic efficiency for all load conditions. Exergy destruction in the components of the ammonia–water absorption refrigeration system is increased with increasing load due to the rise of heat transfer. At intermediate and high loads energy efficiency is increased in the power system, and low values of unit exergetic cost and competitive specific exergoeconomic costs are noticed. The cogeneration system operation at intermediate and high engine loads was proven to be feasible.     

Imbalanced data classification via support vector machines and genetic algorithms

Many real data sets are imbalanced and contain a large number of a certain type of patterns, but a very small number of another type of patterns. Normal classification methods, such as support vector machine (SVM), do not work well for these imbalanced data sets (IDS). It is difficult for SVMs to get the optimal separation hyperplane when they are trained with imbalanced data. In this paper, we propose a genetic algorithm (GA)-based classification method. A draft hyperplane and support vectors are first generated by SVMs. Then, GA is applied to compensate the imbalanced data. Finally, SVM is used again to find the best hyperplane from the generated data points. Compared with the other popular classification algorithms, our method has better classification accuracy for several IDS.     

Heavy metals in cow’s milk and cheese produced in areas irrigated with waste water in Puebla,Mexico

The aim of this work was to determine Ni, Cr, Cu, Zn, Pb, and As levels in raw milk and Oaxaca and ranchero type cheeses, produced in areas irrigated with waste water from Puebla in Mexico. Milk results showed a mean Pb level of 0.03 mg kg^?1, which is above the maximum limit as set by Codex Alimentarius and the European Commission standards. For As a mean value of 0.12 mg kg^?1 in milk was obtained. Mean As and Pb levels in milk were below the Mexican standard. Milk whey and ranchero cheese had mean Pb levels of 0.07 and 0.11 mg kg^?1, respectively. As was higher in Oaxaca and ranchero cheese at 0.17 and 0.16 mg kg^?1, respectively. It was concluded that cheeses made from cow’s milk from areas irrigated with waste water are contaminated with Pb and As, which may represent a health risk.     

Study of keyhole TIG welding by comparative analysis of two high-productivity torches for joining medium-thickness carbon steel plates

In the usual reference works, welding by the keyhole technique has always been associated with welding processes with high energy concentration, such as the laser process or the plasma process. Recent advances in TIG torches are changing how the TIG welding process should be viewed. An example of these recent advances is the torch with the trade name Infocus, the main feature of which, according to its manufacturers, is the capacity for concentration of energy at the electrode tip, by increasing the cooling power of the electrode, which differentiates the Infocus torch from a conventional TIG torch. This concentration of energy allows the Infocus torch to operate by the keyhole technique. Therefore, the aim of the present work is to study the feasibility of employing the keyhole technique with a conventional TIG torch, with the same working conditions as the torch known commercially as Infocus. The tests confirmed that the TIG process can operate by the keyhole technique, without the need for a torch with special characteristics. However, the electrode of the Infocus torch has a longer life, in comparison with a conventional electrode of the same composition, increasing process productivity.