Strain Dependence of the Uniaxial Compression Response of Vegetable Shortening

Many soft food materials, including vegetable shortening, exhibit complex rheological behavior. For shortening, a precise determination of rheological behavior is necessary to understand its functionality as a food ingredient. Commercial vegetable shortening was subjected to monotonic and cyclic uniaxial compression tests at a wide range of loading rates. The elastic modulus determined from unloading was a function of strain, varying between 740 kPa in the shortening’s strain hardening region to 220 kPa at large strain where perfect plasticity had developed. Visual analysis of shortening specimens during the compression process showed that a rate-dependent stress overshoot was attributable to the development of a shear band following strain hardening. An elastoviscoplastic constitutive model was developed to define the complex rate-dependent compression response of vegetable shortening. Using the fundamental parameters obtained from the different types of compression tests, the proposed model accurately predicted the uniaxial compression response of vegetable shortening over a wide range (three decades) of compression rates. A model with predictive capabilities of large strain properties is desirable because shortening is subject to large strain in essentially all applications.     

Tuning Carbon Materials for Supercapacitors by Direct Pyrolysis of Seaweeds

The sea provides a large variety of seaweeds that, because of their chemical composition, are fantastic precursors of nanotextured carbons. The carbons are obtained by the simple pyrolysis of the seaweeds under a nitrogen atmosphere between 600 and 900 °C, followed by rinsing the product in slightly acidic water. Depending on the origin of the seaweed and on the pyrolysis conditions, the synthesis may be oriented to give an oxygen‐enriched carbon or to give a tuned micro/mesoporous carbon. The samples with a rich oxygenated surface functionality are excellent as supercapacitor electrodes in an aqueous medium whereas the perfectly tuned porous carbons are directly applicable for organic media. In both cases, the specific surface area of the attained carbons does not exceed 1300 m² g⁻¹, which results in high‐density materials. As a consequence, the volumetric capacitance is very high, making these materials more interesting than activated carbons from the point of view of developing small and compact electric power sources. Such versatile carbons, obtained by a simple, ecological, and cheap process, could be well used for environment remediation such as water and air treatment.     

Early manifestations of personality and adult health: A life course perspective.

Objective: The aim of this study is to investigate whether individual personality or temperamental qualities that emerge early and persist over the life course, predict adult midlife health. Specific childhood personality attributes considered include distress proneness, behavioral inhibition, and ability to stay focused on a task. Design: Prospective data are from 569 individuals followed from birth into adulthood. Main Outcome Measures: Outcomes include two different measures of adult health: self-rated general health, and number of illnesses in adulthood. Results: Childhood personality attributes related to attention and distress were significantly associated with adult health, with stronger effects evident among women. Children with high attention reported better self-rated health (b = 0.12, p     

Multi-objective Topology Optimization of Thermo-mechanical Compliant Mechanisms

The material characteristics of a structure will change with temperature variation,and will induce stress within the structure.Currently,the optimal design for the topology of compliant mechanisms is mainly performed in single physical field.However,when compliant mechanisms work in high temperature environments,their displacement outputs are generated not only by mechanical load,but also by the temperature variation which may become the prominent factor.Therefore,the influence of temperature must be considered in the design.In this paper,a novel optimization method for multi-objective topology of thermo-mechanical compliant mechanisms is presented.First,the thermal field is analyzed with finite-element method,where the thermal strain is taken into account in the constitutive relation,and the equivalent nodal thermal load is derived with the principle of virtual work.Then the thermal load is converted into physical loads in elastic field,and the control equation of the thermo-mechanical compliant mechanism is obtained.Second,the mathematical model of the multi-objective topology optimization is built by incorporating both the flexibility and stiffness.Meanwhile,the coupling sensitivity function and the sensitivity analysis equations of thermal steady-state response are derived.Finally,optimality criteria algorithm is employed to obtain numerical solution of the multi-objective topology optimization.Numerical examples show that the compliant mechanisms have better performance and are more applicable if the temperature effect is taken into account in the design process.The presented modeling and analysis methods provide a new idea and an effective approach to topology optimization of compliant mechanisms in electrothermic coupling field and multiphysics fields.     

Ultrasonic technique as tool for determining physical and mechanical properties of frozen soils

Ultrasonic velocities of compressional and shear waves in frozen sand, silty-sand and silt were measured at subfreezing temperature and the relationship between acoustic and physical-mechanical properties examined. Ultrasonic measurements revealed that the influence of temperature on ultrasonic velocities is due to the phase transition from water to ice. Different methods were proposed to determine the amount of unfrozen water in frozen soils. The unfrozen water content was measured directly by time domain reflectometry and compared to predicted values using different theoretical approaches. The prediction models showed good agreements with measured values at low temperatures. However, the shape of the curves obtained did not completely satisfying as the estimated unfrozen water fraction near 0 °C was significantly greater than the measured values. Finally, based on the elastic wave theory and measured acoustic velocities the elastic constants of the frozen soils were calculated. The changes in elastic constants were found to be related to the increase in ice content, ice stiffness by ice cementation and a decrease in unfrozen water content.     

MODELLING ADSORPTION EQUILIBRIUM MOISTURE CHARACTERISTICS OF ROUGH RICE

Equilibrium Moisture Content (EMC) data for medium rough rice grain, Lido variety were obtained by equilibrating rice samples at different Equilibrium Relative Humidities (ERH) and Temperatures. The employed models to fit the data were GAB, modified Chung-Pfost, modified Halsey, Modified Henderson, and modified Oswin. The data were evaluated using the standard error of moisture content, mean relative standard error (%P) of the model and the correlation coefficient r². The GAB model by indirect regression described the EMC the best, however its parameters lacked of physical meaning. The modified Chung-Pfost and modified Henderson equations presented a similar fit of the EMCERH relationships. The modified Chung-Pfost equation had lower residual values than the modified Henderson equation and was considered the best model to explain the EMC-ERH relationships.