Dynamic Thermal Analysis of a Power Amplifier

This paper presents dynamic thermal analyses of a power amplifier. All the investigations are based on the transient junction temperature measurements performed during the circuit cooling process. The presented results include the cooling curves, the structure functions, the thermal time constant distribution and the Nyquist plot of the thermal impedance. The experiments carried out demonstrated the influence of the contact resistance and the position of the entire cooling assembly on the obtained results.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Syntheses and Properties of Two-Dimensional, Dicationic Nonlinear Optical Chromophores Based on Pyrazinyl Cores

Six new dicationic 2D nonlinear optical (NLO) chromophores with pyrazinyl-pyridinium electron acceptors have been synthesized by nucleophilic substitutions of 2,6-dichloropyrazine with pyridyl derivatives. These compounds have been characterized as their PF_6^− salts by using various techniques including electronic absorption spectroscopy and cyclic voltammetry. Large red shifts in the intense, π → π* intramolecular charge-transfer (ICT) transitions on replacing −OMe with –Nme_2 substituents arise from the stronger π-electron donor ability of the latter. Each compound shows a number of redox processes which are largely irreversible. Single crystal X-ray structures have been determined for five salts, including two nitrates, all of which adopt centrosymmetric packing arrangements. Molecular first hyperpolarizabilities β have been determined by using femtosecond hyper-Rayleigh scattering at 880 and 800 nm, and depolarization studies show that the NLO responses of the symmetric species are strongly 2D, with dominant “off-diagonal” β_(zyy) components. Stark (electroabsorption) spectroscopic measurements on the ICT bands afford estimated static first hyperpolarizabilities β_0. The directly and indirectly derived β values are large, and the Stark-derived β_0 response for one of the new salts is several times greater than that determined for (E)-4′-(dimethylamino)-N-methyl-4-stilbazolium hexafluorophosphate. These Stark spectroscopic studies also permit quantitative comparisons with related 2D, binuclear RuII ammine complex salts

Thermodynamics of trajectories of the one-dimensional Ising model

We present a numerical study of the dynamics of the one-dimensional Ising model by applying the large-deviation method to describe ensembles of dynamical trajectories. In this approach trajectories are classified according to a dynamical order parameter and the structure of ensembles of trajectories can be understood from the properties of large-deviation functions, which play the role of dynamical free-energies. We consider both Glauber and Kawasaki dynamics, and also the presence of a magnetic field. For Glauber dynamics in the absence of a field we confirm the analytic predictions of Jack and Sollich about the existence of critical dynamical, or space-time, phase transitions at critical values of the "counting" field $s$. In the presence of a magnetic field the dynamical phase diagram also displays first order transition surfaces. We discuss how these non-equilibrium transitions in the 1$d$ Ising model relate to the equilibrium ones of the 2$d$ Ising model. For Kawasaki dynamics we find a much simple dynamical phase structure, with transitions reminiscent of those seen in kinetically constrained models.Comment: 23 pages, 10 figure

Animal Agriculture in South Carolina: A Fact Book

Livestock Production/Industries,

Stomach Content Analysis of Pterygoplichthys Pardalis From the Air Hitam River, Payung Sekaki District, Riau Province

Pterygoplichthys pardalis is a type of freshwater fish that live in the Air Hitam River, one of polluted river in Riau. Eventhough the river is polluted, but this species well developed in that river. To understand the stomach content of that fish and its relationship with size, sex and level of maturity, a study has been conducted from February to May 2015. There were 169 fishes captured, however only 91 fishes were used for stomach content study as the other had empty stomach. The stomach content was analyzed and was used as a basis to calculate the Preponderance Index (PI). Results shown that the main food of P. pardalis is Bacillariophyceae (PI 41.19%), small fishes (91-124 mm TL) tend to consume Cyanophyceae (PI53.54%), while the big fish (more than 295 mm TL) tend to consume Bacillariophyceae (PI 45,48%) and rest of crustacea (PI 46,66%). Male eat more Cyanophyceae (PI 46,69%), the female consume Bacillariophyceae (PI 39,05%). Fish with low maturity level (2nd and 3rd maturity level) tend to eat Chlorophyceae (PI 48.81%) and Bacillariophyceae (PI 34.19%), while the mature fish prefer to consume Chlorophyceae (PI 37.14%). Based on data obtained, it can be concluded that the main food of P. pardalis was various and it is related to body size, sex and gonad maturity level

Novel software for medical and technical Thermal Object Identification (TOI) using dynamic temperature measurements by fast IR cameras

This paper presents a thermal analysis and methodology of thermal parameters identification of thermal multilayer structures using thermographic measurements after dynamic heating (or cooling) the investigated objects. During the thermal transient process, thermal images are recorded, with the highest possible frame rate of the camera. Then, temperature and power signals are transformed into the frequency domain, to get finally the thermal time constants distribution corresponding to the thermal parameters of the structure. A brief description of TOI program developed in MATLAB environment as well as the exemplary identifications of 2 different thermal objects are shown