Control of multivariable non-linear systems by the sliding mode method

Sliding mode control is a technique that has been successfully used for SISO nonlinear systems in controllable canonical form and for some particular multivariable system structures. It is the purpose of this paper to generalize the sliding mode approach to a larger class of multivariable systems and to illustrate the relationship between I/O linearization and the sliding mode approach when the error dynamics on the sliding surfaces are chosen to be linear and time-invariant. The developed technique is applied to a multivariable non-linear example.     

PORE SIZE DISTRIBUTION AND STRUCTURE OF A COOKED BEEF PRODUCT AS AFFECTED BY VACUUM COOLING

True density, apparent density, and pore size distribution were measured for a vacuum cooled cooked beef product using helium pycnometry and mercury porosimetry. Vacuum cooled samples resulted in the development of high porosity and lower density in comparison to more conventional cooling methods. Pore size distribution for vacuum cooled samples revealed the presence of random pore sizes with no distinct pore size but rather a pore size range of 10 μm to 0.02 μm. It was determined that the vast majority of porosity in vacuum cooled samples was composed of void space volume as distinct to regular pores. Analysis of estimated diffusion coefficients revealed that the efficiency of vacuum cooling is dependent on the development of porosity within the samples during cooling which leads to more efficient cooling times and higher diffusion rates in samples with higher porosity and larger pore size distributions.     

味彩阁

在一个大房子里有六个小房子。 六个房子一字排开，可以独门独户地做包房，也可以通过打开折滑式门屏，轻松地合二为一、合三为一……合六为一，开PARTY、办宴会……多样组合，多样用途。     

INFLUENCE OF STARVATION, TEMPERATURE, AND pH ON CULTURABILITY OF ESCHERICHIA COLI O157:H7

In farm and food processing environments Escherichia coli O157:H7 can survive for days to months. In this study, we investigated the influence of starvation, pH (pH 4 or 7), temperature (4, 10 and 22C), and exposure to chlorine (50, 100, 150, 200 ppm) on culturability of E. coli O157:H7. The culturable cell population in PBS decreased to an undetectable level at 4C and 10C, but not at 22C during the experimental period. Cells suspended in PBS adjusted to pH 4 lost culturability more rapidly than at pH 7. Culturable cells were not detectable after exposure to chlorine, however, viable cell populations in the range of 1 – 2 log remained stable for 5 days. During loss of culturability two distinct morphological cell populations emerged; typical rod shaped and coccoid shaped cells. In this study, independent of exposure to chlorine, conditions of low temperature and low pH had the greatest influence on entry of E. coli O157:H7 into a VNC state.     

EFFECT OF ENZYMATIC TENDERIZATION, BLADE TENDERIZATION, OR PRECOOKING ON SENSORY AND PROCESSING CHARACTERISTICS OF BEEF BACON

The objectives of this study were to evaluate the effects of enzymatic tenderization, blade tenderization, or precooking on the visual and palatability attributes of beef bacon. Injection of 30 ppm bromelin into beef plates processed into beef bacons significantly (P < 0.05) reduced visual binding and appearance scores compared with the control, 10 ppm- and 20 ppm-injected products. Bacons produced from Choice grade carcasses were saltier, more bacon flavored, softer, higher in fat content, and had lower shear force values than bacons produced from Utility grade carcasses. Precooking of injection-cured beef bacons decreased slice integrity, saltiness, and flavor intensity and increased toughness, shear force, and off-flavor compared with the controls.     

Failure Probability at the Predicted Minimum Lifetime After Proof Testing

Experimental variation in crack growth parameters introduces an uncertainty in the predicted minimum lifetime after proof testing that results in a possibility of failure at times less than the "minimum" lifetime. This failure probability is estimated with a Monte carlo simulation technique. A A example is given of how this failure probability can be made vanishingly small by increasing the proof stress or by decreasing the allowable stress or permissible lifetime in service.