Food Preferences, Food Intake, and Growth of the F\u3csub\u3e1\u3c/sub\u3e Hybrid of Grass Carp ♀ X Bighead Carp ♂

Hybrid carp from the cross grass carp Ctenopharyngodon idella ♀ X bighead carp Aristichthys nobilis ♂ preferred filamentous algae and Najas guadalupensis over Ceratophyllum demersum. Medium-sized (273 g) and large hybrids (360 g) consumed more plant material and grew faster than small hybrids (77 g) at 14 and 22 C in aquaria. Aquarium data suggest that it will require at least twice as many hybrids as grass carp of the same size to obtain the same level of vegetation control

Food Intake of the Largemouth Bass

During 18 months of electrofishing a sample of 991 adult largemouth bass (Micropterus salmoides) was taken from Crab Orchard Lake. The stomach contents were removed in the field with a gastroscope. Gizzard shad (Dorosoma cepedianum) constituted the principal forage fish. Approximately 50% of the bass collected had empty stomachs. As the size of bass increased, the food intake as a percent of body weight decreased. Ninety percent of the bass stomachs contained one food item. When more than one food item was found, they were usually in the same stage of digestion. It is suggested that the high percent of empty stomachs was related to hunting success, or that the onset of the feeding stimulus in association with rate of digestion might result in a periodicity of feeding that involves a high percent of empty stomachs. A higher relative intake of food by small bass was postulated to be a result of the bass\u27s typically consuming only one fish. Inasmuch as the forage fish were relatively uniform in size, one fish constituted a large meal for a small bass but not for a large bass

Gear-Specific Population Demographics of Channel Catfish in a Large Midwestern River

Various gear types have been used to sample populations of channel catfish Ictalurus punctatus in lotic systems. However, these gears produce different population characteristics (i.e., recruitment, growth, and mortality). We compared the population demographics of channel catfish in the Wabash River, Indiana, sampled with baited 25- and 32-mm-bar mesh hoop nets and three-phase alternating current (AC) electrofishing. Based on catch per unit effort, the relative abundance of channel catfish sampled with 32-mm hoop nets was lower than that of fish sampled with 25-mm hoop nets and AC electrofishing. Each gear type also resulted in a different length frequency, mean length increasing progressively in sampling with 25-mm hoop nets, 32-mm hoop nets, and AC electrofishing. Similarly, age-frequency distributions differed among gears. The 25-mm hoop nets biased the age structure toward younger individuals (mean age = 2.5), whereas both 32-mm hoop nets (mean age = 4.0) and AC electrofishing (mean age = 5.8) included older fish. Catch-curve analysis generated different mortality rates for the three gear types, the mortality rate being highest (50%) in fish sampled with 25-mm hoop nets. Gear-specific size and age structures led to differences in von Bertalanffy statistics among the 25-mm hoop nets and AC electrofishing, while the results for 32-mm hoop nets were uninterpretable. Because the different gears led to conflicting parameter estimates, management practices based on sampling with single gears may be contradictory. Given the differences in gear selectivity, biologists need to approach management cautiously until calibration to the true size and age structure is conducted

Control of a SiC 2.5 MHz resonant full-bridge inverter for inductively driven plasma

The electronic ballast of an inductively driven plasma faces a mostly inductive, variable load impedance. The SiC full-bridge inverter uses the inductive behavior to achieve zero-voltage-switching and a switching frequency of 2.5 MHz, at 3.9 kVA and 764W in the plasma. The control is realized on a modern, small TI Piccolo microcontroller with a high-resolution PWM module and compensates for the variable load impedance. We present design and experimental results of a 2.5 MHz inverter for inductively driven plasma without the need for a large FPGA controller

Comparing open and closed vertical refrigerated display cabinets at mild and tropical external environments

This study is within the activities of Project “PrunusPós - Optimization of processes for the storage, cold conservation, active and/or intelligent packaging and food quality traceability in post-harvested fruit products”, project n.º PDR2020-101-031695, Partnership n.º 87, initiative n.º 175, promoted by PDR 2020 and co-funded by FEADER within Portugal 2020.This paper reports the results of experimental tests performed according to ISO 23953 in vertical open and closed refrigerated display cabinets (VORDC vs. VCRDC). Tests were performed at a mild climate class (n. º 3: T=25°C; φ=60%) and a tropical one (n. º 6: T=27°C; φ=70%). The direct energy consumption is 46% higher at VCRDC due to the heated glass doors frame and defrost heaters. The product simulator temperature is higher and more stable at VORDC. The highest product simulator temperature is lower (-1.4°C) at the VCRDC and less stable (+2.7°C variation) due to the opening doors period. The total mass of condensed water at the evaporator is reduced 87% and the total heat load is 77% lower at the VCRDC. Thus, the estimated total energy consumption is reduced 42%. Given the current concerns with energy consumption and sustainability of the heat exchange processes, the VCRDC provide the best solution.info:eu-repo/semantics/publishedVersio

Variation of the thermal performance of open multideck display case due to the procedure of setting the external air velocity

This paper reports the experimental results with an open multideck display case with dual air curtain. Manufacturers seek during the design phase of the equipment to certify its suitability to the testing standards with the lowest energy consumption and ensuring food safety. The testing standard ISO 23953 is usually followed to determine the thermal cooling load. The thermal cooling load depends on the procedure to set the external air velocity. According to ISO 23953, the mean horizontal air velocity, with the refrigerated display case switched off, shall be 0.2 m s-1. This paper reports experimental test results where the initial procedure of setting the air velocity followed two different methods. Considering that (1) the display case is initially switched off as required by ISO 23953 and (2) the display case is initially switched on and the external air velocity is adjusted to the required level using auxiliary fans. After reaching steady state conditions, the 24-hour tests began with the display case switched on.info:eu-repo/semantics/publishedVersio

Numerical experimental evaluation of the aerodynamic drag of the air curtain in Vertical Open Refrigerated Display Cabinets

This paper presents the experimental and numerical results of a set of air curtain evaluations in a Vertical Open Refrigerated Display Cases (VORDC) when subjected to external disturbances due to the transfer of people in front of the air curtain. Previous experimental studies identified that the stability of the air curtain depends on the climatic conditions and ambient air movement inside the stores. The ambient air and VORDC air curtain can be disturbed during the movement of people in front of the VORDC, causing a certain amount of cold air to flow out of the VORDC and consequently hot and humid air entering. It is not possible to quantify exclusively the increase in energy consumption due to the transfer of people in the real case, due to the other variables involved in the process. Thus, a robot (Automated Mannequin for Interference Reproduction in the Air Curtain - MARIA) was mounted on a rail placed around the VORDC, in a climate chamber with controlled environment according to climatic class (n. º 3: T=25°C; =60%). MARIA performed clockwise and counterclockwise movements around the VORDC, with velocities of 0.2 m.s-1 at 0.8 m.s-1, with a pitch of 0.2 m.s-1. For the numerical evaluation, a 3D CFD model was developed to predict and analyze the air flow and heat transfer in the air curtain and outside both ways, refrigerated space and ambient air due to transfer of a body parallel to the air curtain.info:eu-repo/semantics/publishedVersio