Losses in self-oscillating ballasts for electrode-type compact fluorescent lamps

Commercially available integrated compact fluorescent lamps (CFLs) use self-resonant ballasts on grounds of simplicity and cost. To understand how to improve ballast efficiency, it is necessary to quantify the losses. The losses occurring in these ballasts have been directly measured using a precision mini-calorimeter. In addition, a Pspice model has been used to simulate the performance of an 18 W integrated CFL. The lamp has been represented by a behavioural model and Jiles-Atherton equations were used to model the current transformer core. The total loss is in close agreement with measurements from the mini-calorimeter, confirming the accuracy of the model. The total loss was then disaggregated into component losses by simulation, showing that the output inductor is the primary source of loss, followed by the inverter switches. © 2011 The Institution of Engineering and Technology.

Studies on thermal deffusivity [i.e. diffusivity] and conductivity of fresh and dry fish

Thermal diffusivity (α) and conductivity (K) of fresh and dry cured fish at different moisture levels were investigated by a calorimeter (regular regime) method and transient line source technique. Thermal conductivity has a linear correlation with packing density and percentage water content. K values calculated from formula method and line source technique are comparable.

Parameter extraction and calorimetric validation for a silicon carbide jfet pspice model

This paper focuses on the PSpice model of SiC-JFET element inside a SiCED cascode device. The device model parameters are extracted from the I-V and C-V characterization curves. In order to validate the model, an inductive test rig circuit is designed and tested. The switching loss is estimated both using oscilloscope and calorimeter. These results are found to be in good agreement with the simulated results.

从灰分及氮含量计算鱼体能量含量的一个简易方法

<正> 鱼体能量含量的测定是鱼类能量学研究的一个重要内容。近来的研究表明,测定鱼体能量含量上的误差,是造成估算鱼类能量收支误差的一个重要原因。测定生物能量含量的最可靠的方法为用热量计(calorimeter)直接测定。但热量计价格昂贵,不易普及;测量中需用铂丝作引燃材料,成本较高;热量计的操作也较费时。一般测定鱼体能量含量的方法为:

Inclusive pi(0), eta, and direct photon production at high transverse momentum in p plus p and d plus Au collisions at root s(NN)=200 GeV

We report a measurement of high-p(T) inclusive pi(0), eta, and direct photon production in p + p and d + Au collisions at root s(NN) = 200 GeV at midrapidity (0 < eta < 1). Photons from the decay pi(0) -> gamma gamma were detected in the barrel electromagnetic calorimeter of the STAR experiment at the Relativistic Heavy Ion Collider. The eta -> gamma gamma decay was also observed and constituted the first eta measurement by STAR. The first direct photon cross-section measurement by STAR is also presented; the signal was extracted statistically by subtracting the pi(0), eta, and omega(782) decay background from the inclusive photon distribution observed in the calorimeter. The analysis is described in detail, and the results are found to be in good agreement with earlier measurements and with next-to-leading-order perturbative QCD calculations.

Calorimetric study on two biphenyl liquid crystals

The molar heat capacities of the two biphenyl liquid crystals, 3BmFF and 3BmFFXF3, with a purity of 99.7 mol% have been precisely measured by a fully automated precision adiabatic calorimeter in the temperature range between T = 80 and 350 K. Nematic phase-liquid phase transitions were found between T = 297 K and 300 K with a peak temperature of T-peak = (298.071 +/- 0.089) K for 3BmFF, and between T = 316 and 319 K with a peak temperature of T-peak = (315.543 +/- 0.043) K for 3BmFFXF3. The molar enthalpy (Delta(trs)H(m)) and entropy (Delta(trs)S(m)) corresponding to these phase transitions have been determined by means of the analysis of the heat capacity curves, which are (15.261 +/- 0.023) U mol(-1) and (51.202 +/- 0.076) J K-1 mol(-1) for 3BmFF, (31.624 +/- 0.066) kJ mol(-1) and (100.249 +/- 0.212) J K-1 mol(-1) for 3BmFFXF3, respectively. The real melting points (TI) and the ideal melting points (TO) with no impurities of the two compounds have been obtained from the fractional melting method to be (298.056 +/- 0.018) K and (298.165 +/- 0.038) K for 3BmFF, (315.585 +/- 0.043) K and (315.661 +/- 0.044) K for 3BmFFXF3, respectively. In addition, the transitions of these two biphenyl liquid crystals from nematic phase to liquid phase have further been investigated by differential scanning calorimeter (DSC) technique; the repeatability and reliability for these phase transitions were verified. (C) 2004 Elsevier B.V. All rights reserved.

Low-temperature heat capacities and derived thermodynamic functions of cyclohexane

The low-temperature heat capacities of cyclohexane were measured in the temperature range from 78 to 350 K by means of an automatic adiabatic calorimeter equipped with a new sample container adapted to measure heat capacities of liquids. The sample container was described in detail. The performance of this calorimetric apparatus was evaluated by heat capacity measurements on water. The deviations of experimental heat capacities from the corresponding smoothed values lie within +/-0.3%, while the inaccuracy is within +/-0.4%, compared with the reference data in the whole experimental temperature range. Two kinds of phase transitions were found at 186.065 and 279.684 K corresponding solid-solid and solid-liquid phase transitions, respectively. The entropy and enthalpy of the phase transition, as well as the thermodynamic functions {H-(T)- H-298.15 K} and {S-(T)-S-298.15 K}, were derived from the heat capacity data. The mass fraction purity of cyclohexane sample used in the present calorimetric study was determined to be 99.9965% by fraction melting approach.

Heat capacities and thermodynamic properties of chrysanthemic acid

The heat capacities of chrysanthemic acid in the temperature range from 80 to 400 K were measured with a precise automatic adiabatic calorimeter. The chrysanthemic acid sample was prepared with the purity of 0.9855 mole fraction. A solid-liquid fusion phase transition was observed in the experimental temperature range. The melting point, T-m, enthalpy and entropy of fusion, Delta(fus)H(m), Delta(fus)S(m), were determined to be 390.741 +/- 0.002 K, 14.51 +/- 0.13 kJ mol(-1), 37.13 +/- 0.34 J mol(-1) K-1, respectively. The thermodynamic functions of chrysanthemic acid, H-(T)-H-(298.15), S-(T)-S-(298.15) and G((T))-G((298.15)) were reported with a temperature interval of 5 K. The TG analysis under the heating rate of 10 K min(-1) confirmed that the thermal decomposition of the sample starts at ca. 410 K and terminates at ca. 471 K. The maximum decomposition rate was obtained at 466 K. The purity of the sample was determined by a fractional melting method.

Low-temperature heat capacities and standard molar enthalpy of formation of aspirin

Molar heat capacities (C-p,C-m) of aspirin were precisely measured with a small sample precision automated adiabatic calorimeter over the temperature range from 78 to 383 K. No phase transition was observed in this temperature region. The polynomial function of Cp, vs. T was established in the light of the low-temperature heat capacity measurements and least square fitting method. The corresponding function is as follows: for 78 Kless than or equal toTless than or equal to383 K, C-p,C-m/J mol(-1) K-1=19.086X(4)+15.951X(3)-5.2548X(2)+90.192X+176.65, [X=(T-230.50/152.5)]. The thermodynamic functions on the base of the reference temperature of 298.15 K, {DeltaH(T)-DeltaH(298.15)} and {S-T-S-298.15}, were derived.

Heat capacity and thermodynamic properties of pyrimethanil myristic salt (C26H41N3O2)

Pyrimethanil myristic salt was synthesized and its heat capacities were measured with an automated adiabatic calorimeter over the temperature range from T = (79 to 360) K. The melting point, molar enthalpy, Delta(fus)H(m) and entropy, Delta(fus)S(m), of fusion of this compound were determined to be (321.84 +/- 0.05) K, (56.53 +/- 0.03) kJ . mol(-1) and (175.64 +/- 0.05) J . mol(-1) . K-1, respectively. The purity of the compound was calculated to be 98.99 mol% by using the fractional melting technique. The thermodynamic functions relative to the reference temperature, T = 298.15 K, were calculated based on the heat capacity measurements in the temperature ranges from T = (80 to 360) K. The TG-DTG results demonstrate that the mass loss of the sample takes place in one step with the maximum rate at T = 500 K, which was caused by evaporation of the sample. (C) 2004 Elsevier Ltd. All rights reserved.

Heat capacity and thermodynamic properties of crystalline ornidazole (C7H10ClN3O3)

The molar heat capacities of 1-(2-hydroxy-3-chloropropyl)-2-methyl-5-nitroimidazole (Ornidazole) (C7H10CIN3O3) with purity of 99.72mol% were measured with an adiabatic calorimeter in the temperature range between 79 and 380K. The melting-point temperature, molar enthalpy Delta(fus)H(m), and entropy, Delta(fus)S(m), of fusion of this compound were determined to be 358.59 +/- 0.04K, 21.38 +/- 0.02 kJ mol(-1) and 59.61 +/- 0.05 J K-1 mol(-1), respectively, from fractional melting experiments. The thermodynamic function data relative to the reference temperature (298.15 K) were calculated based on the heat capacities measurements in the temperature range from 80 to 380 K. The thermal stability of the compound was further investigated by DSC and TG. From the DSC curve an intensive exothermic peak assigned to the thermal decomposition of the compound was observed in the range of 445-590 K with the peak temperature of 505 K. Subsequently, a slow exothermic effect appears when the temperature is higher than 590 K, which is probably due to the further decomposition of the compound. The TG curve indicates the mass loss of the sample starts at about 440K, which corresponds to the decomposition of the sample. (C) 2003 Elsevier B.V. All rights reserved.

Thermodynamic studies of monuron

Monuron (C9H11ClN2O; N,N-dimethyl-N'-(4-chlorophenyl) urea, CAS 150-68-5) was synthesized and the heat capacities of the compound were measured in the temperature range from 79 to 385 K with a high precision automated adiabatic calorimeter. No phase transition or thermal anomaly was observed in this range. The enthalpy and entropy data of the compound relative to the reference temperature 298.15 K were derived based on the heat capacity data. The thermodynamic properties of the compound were further investigated through DSC and TG analysis. The melting point, the molar enthalpy, and entropy of fusion were determined to be 447.6 +/- 0.1 K, 29.3 +/- 0.2 kJ mol(-1), and 65.4 J K-1 mol(-1), respectively. (C) 2004 Elsevier B.V. All rights reserved.

Calorimetric study and thermal analysis of crystalline nicotinic acid

As one primary component of Vitamin B-3, nicotinic acid [pyridine 3-carboxylic acid] was synthesized, and calorimetric study and thermal analysis for this compound were performed. The low-temperature heat capacity of nicotinic acid was measured with a precise automated adiabatic calorimeter over the temperature rang from 79 to 368 K. No thermal anomaly or phase transition was observed in this temperature range. A solid-to-solid transition at T-trs = 451.4 K, a solid-to-liquid transition at T-fus = 509.1 K and a thermal decomposition at T-d = 538.8 K were found through the DSC and TG-DTG techniques. The molar enthalpies of these transitions were determined to be Delta(trs)H(m =) 0.81 kJ mol(-1), Delta(fus)H(m) 27.57 kJ mol(-1) and Delta(d)H(m) = 62.38 kJ mol(-1), respectively, by the integrals of the peak areas of the DSC curves.

Heat capacity and enthalpy of fusion of penconazole (C13H15C12N3)

Low-temperature heat capacities of penconazole (C13H15Cl2N3) were precisely measured with an automated adiabatic calorimeter over the temperature rang from 78 to 364 K. The sample was observed to melt at 332.38 +/- 0.06 K. The molar enthalpy and entropy of fusion of the compound were determined to be 33580 +/- 11 J mol(-1), 101.03 +/- 0.02 J mol(-1) K-1, respectively. Further research of the melting process for this compound was carried out by means of differential scanning calorimetry (DSC) technique. The result was in agreement with that obtained from the measurements of heat capacities. (C) 2003 Elsevier B.V. All rights reserved.

Thermodynamic study of ibuprofen by adiabatic calorimetry and thermal analysis

Molar heat capacities of ibuprofen were precisely measured with a small sample precision automated adiabatic calorimeter over the temperature range from 80 to 400 K. The polynomial functions of C-p,C-m (J K-1 mol(-1)) versus T were established on the heat capacity measurements by means of the least fitting square method. The functions are as follows: for solid ibuprofen, at the temperature range of 79.105 K less than or equal to T less than or equal to 333.297 K, C-p,C-m = 144.27 + 77.046X + 3.5171X(2) + 10.925X(3) + 11.224X(4), where X = (T - 206.201)/127.096; for liquid ibuprofen, at the temperature range of 353.406 K less than or equal to T less than or equal to 378.785 K, C-p,C-m = 325.79 + 8.9696X - 1.6073X(2) - 1.5145 X-3, where X = (T - 366.095)/12.690. A fusion transition at T = 348.02 K was found from the C-p-T curve. The molar enthalpy and entropy of the fusion transition were determined to be 26.65 kJ mol(-1) and 76.58 J mol(-1) K-1, respectively. The thermodynamic functions on the base of the reference temperature of 298.15 K, (H-T - H-298.15) and (S-T - S-298.15), were derived. Thermal characteristic of ibuprofen was studied by thermo-gravimetric analysis (TG-DTG) and differential scanning calorimeter (DSC). The temperature of fusion, the molar enthalpy and entropy of fusion obtained by DSC were well consistent with those obtained by adiabatic calorimeter. The evaporation process of ibuprofen was investigated further by TG and DTG, and the activation energy of the evaporation process was determined to be 80.3 +/- 1.4 kJ mol(-1). (C) 2003 Elsevier B.V. All rights reserved.