Performance analysis of two serial-search acquisition schemes for FH spread spectrum signals

Initial synchronization (acquisition) schemes of frequency hopped (FH) spread spectrum signals often make use of serial-search acquisition techniques. Two FH serial-search acquisition schemes are introduced and analysed. These schemes are the fixed dwell-time with false alarm memory (FDT/FAM) and the double dwell-time with binary integration (DDT/BI) scheme. Statistical properties namely, probability density function, characteristic function and mean value of the random acquisiton time of each acquisition scheme are obtained. The performances of the FDT, FDT/FAM and DDT/BI acquisition schemes are established and compared in the presence of partial band noise jamming, partial band tone jamming and additive white gaussian noise (AWGN). The results indicate that the DDT/BI acquisition scheme outperforms the FDT and FDT/FAM acquisition schemes.     

INHIBITION OF SURFACE GROWTH OF TOXIGENIC AND NONTOXIGENIC ASPERGILLI AND PENICILLIA BY EUGENOL, ISOEUGENOL AND MONOLAURIN

Sabouraud dextrose agar, containing up to 300 ppm of eugenol, isoeugenol or monolaurin, was prepared. Eight strains of mycotoxin and non-mycotoxin-producing Aspergillus spp. and Penicillium spp. were tested. Spore suspensions were spotted in the center of agar plates and the linear (radial) growth rate was measured during incubation. All agents inhibited mold growth, but isoeugenol and eugenol were more effective than monolaurin. The average decreases in linear growth rate in the presence of eugenol, isoeugenol and monolaurin were 56, 43 and 11% at 100 ppm and 81, 85 and 15% at 200 ppm, respectively. At 300 ppm eugenol and isoeugenol, all fungi were inhibited completely; however, monolaurin (up to 2000 ppm) did not prevent mold growth. Except for P. viridicatum NRRL 6062, the molds tested did not vary significantly (at p=0.05) in degree of inhibition by any particular antifungal agent .
A. parasiticus was grown in a yeast extract dextrose broth containing 100 ppm of the antifungal agents. Decreases in mycelial dry weight in the presence of eugenol, isoeugenol and monolaurin were 5.3, and 7.9, 10.5%, respectively. The corresponding reductions in aflatoxin B₁ synthesized were 58, 57 and 25%. In conclusion, eugenol and isoeugenol have strong antifungal properties which are best manifested when the surface growth of molds on solid media is monitored .     

Simplified expression for the expected error span recovery for variable length codes

An expression in the form of a series expansion for the error span recovery for variable length codes is presented. Numerical results for both the error span recovery and its standard deviation show complete agreement with those obtained via the complex exact functions. The expression is simple and can be applied to any model where the exact expression is prohibitively complicated.     

HEATING UNIFORMITY AND RATES IN A DOMESTIC MICROWAVE COMBINATION OVEN

Physics-based modeling complemented with magnetic resonance imaging (MRI) for validation can provide a novel means to understand and thereby optimize combination heating processes. The objectives of this study were to compare heating patterns in a combination of radiant, forced air and microwave oven measured by MRI with those predicted by coupled electromagnetics-heat transfer model; quantify speed and uniformity of heating for the different combination modes; determine the effect of food dielectric properties on heating patterns; and delineate the nature of individual heating modes and their combinations. The modes of radiant heating through heating elements and forced convection by fan led to a more uniform heating compared with the faster (but less uniform) heating method provided by the microwaves. Combination methods were faster than radiant, forced-air and microwave-only heating. Although the speed of heating increased appreciably for combination modes, the nonuniformity of heating did not increase as much.

PRACTICAL APPLICATIONS

The results from the study can be used to develop design recommendations/guidelines for combination heating for different thermal processes such as baking, broiling, roasting and reheating of different materials, grouping them based on their properties. The research can benefit the consumers, food services and equipment manufacturers to understand the combination heating process in a better way and to, thereby, use it efficiently. Without a fundamental understanding of the effect of various combinations, optimization of heating can be intractable. The fundamental approach used in this study would, therefore, help consumers and food services in preparation of safe and high-quality foods through combination heating. The work would also help equipment manufacturers in optimizing the designs of combination-heating ovens.     

TEXTURAL PROPERTIES OF STORED AND IRRADIATED TIOGA STRAWBERRIES*

Fresh as well as irradiated Tioga strawberries were softer, required smaller forces to puncture and to compress, and exhibited smaller degrees of elasticity and recoverability from applied stress than the stored berries. Thus, fresh or irradiated strawberries should be more susceptible to mechanical damage during handling, shipping and marketing than the stored fruits.     

TEXTURAL AND ELASTIC PROPERTIES OF IRISH POTATOES II.

Unprocessed steam-peeled potatoes exhibited lower apparent moduli of deformability and elasticity than unpeeled or abrasion-peeled potatoes. Both moduli decreased upon thermal processing and on storage of the processed product. The degree of elasticity and energy capacity decreased, while mechanical hysteresis increased, due to peeling prior to processing. The processed Sebago variety showed greater mechanical hysteresis than the Red LaSoda variety. The apparent elastic properties of processed potatoes exhibited varied trends due to the peeling method and storage as evidenced by the significant interaction of these two main variables. The results obtained suggest that apparent elastic moduli are not reliable indices of the degree of firmness of the peeled and processed Irish potatoes. Texture measurements on these potatoes should involve destructive forces and deformations to give true indications of differences in firmness.     

TEXTURAL AND ELASTIC PROPERTIES OF IRISH POTATOES: I. Textural Properties*

Steam-peeled unprocessed potatoes showed the least hardness, gumminess, and resistance to shear or to compression forces in comparison to those peeled by lye or by abrasion. Fracturability values were greater than hardness values for the unprocessed potatoes, while the reverse was true for processed potatoes. Processed lye-peeled potatoes showed the greatest amount of cohesiveness and gumminess, and required the largest forces to shear or compress. The peeling method had no observed effect on adhesiveness values of processed potatoes. Texture profile parameters as well as resistance to shear or compression forces, and sensory hardness ratings increased during storage of processed potatoes. Steam and lye-peeled potatoes were more preferred organoleptically than abrasion-peeled potatoes.     

Optical and electrical nano eco-sensors using alternative deposition of charged layer

This review focuses on layer by layer (LBL) assembly-based nano ecological sensor (hereafter, eco-sensor) for pesticide detection, which is one of the most versatile methods. The effects of pesticides on human health and on the environment (air, water, soil, plants, and animals) are of great concern due to their increasing use. We highlight two of the most popular detecting methods, i.e., fluorescence and electrochemical detection of pesticides on an LBL assembly. Fluorescence materials are of great interest among researchers for their sensitivity and reliable detection, and electrochemical processes allow us to investigate synergistic interactions among film components through charge transfer mechanisms in LBL film at the molecular level. Then, we noted some prospective directions for development of different types of sensing systems.