The industrial preparation of pasteurized soft boiled eggs requires meticulous planning of the thermal process. Requirements on keeping the yolk liquid and on extinction of potential salmonella allow little leeway in the creation of this process. The variation of the eggs' properties adds to the complexity. Thermal simulation of heat transfer within an egg is needed to get correlation data between transient temperature distribution and the egg's dimensional and material properties. A fast simulator of conductive transient heat transfer with a fixed grid of cells is developed for this purpose. The motivation for achieving the highest simulation speed was the potential integration of a simulation tool for simulation based predictions into an embedded control system. The simulated volume is a cylinder. The simulated object (the egg) is defined within the cylinder. Simulation results are analysed and used in the creation of the thermal process which results in certified pasteurized soft boiled eggs. The presented approach to the design of transient simulation can be used for applications ranging beyond the transient thermal simulation of foods. It can be adapted for any transient simulation where the local temporal intensity of changes depends on gradients and the properties of the matter.
When studying an electric circuit, one can describe the circuit using equations. The equations can be coded into a computer program and iterated with fixed time step through time of interest, which generates simulation results. A specific methodology is needed for the purpose. The methodology of simulation of equations is developed and presented. Using this approach there is no black box (a general-purpose simulation tool) between the student or an engineer who is simulating the circuit, and the circuit itself. The use of ''black boxes'' -general-purpose simulators -is of great value when optimising circuits, but they can leave ''black holes'' when it is about understanding circuit principles and/or exploring new circuit ideas. Simulating equations leaves no space for ''simulation noise''. The circuit is DC-wise analysed at sequential moments in time. Equations, which describe circuit components that store energy (capacitors and inductors), connect in time sequential DC analyses. The simulation of equations adds to the understanding of existing circuits and it has potential in the creation of new circuits. Time-and/or signal-and/or environment-dependent devices can be easily included in the simulation of equations. Test cases show a perfect match between simulated and known results for the analysed circuits. Programming efforts for the simulation of equations are at a manageable level for even a moderately proficient programmer.
Tight assembly of stator windings with no insulation paper damage is a manufacturing challenge. We evaluate different sets of parts according to the following parameters: magnet wire thickness, stator slot smoothness, length of the straight magnet wire after the slot end, and type and amount of insulation cap at the end of the slot. These parameters have discrete values with small differences between them. The damage criterion is the decrease of the insulation paper breakdown voltage after assembly/disassembly of parts, assembled in a small set of designed experiments. Parameter values, i.e., levels at individual experiments are set by an orthogonal experiment matrix. Repetition of each experiment provides statistical significance. Data analysis shows that the additive model alone is not sufficient due to the high correlation of the parameters' influences. We extend the model to include interparameter influences, which we model by adding a virtual parameter. The extended additive model generates parameter values that do not degrade the insulation paper breakdown voltage within the manufacturing process. These values are verified by repetitions of the control experiment. INDEX TERMS Analysis of variance, breakdown voltage, design for experiments, design for manufacture, dielectrics and electrical insulation, extended additive model, insulation paper damage, insulation testing, interparameter influence, in-wheel motor reliability, matrices, metal-insulator structures, orthogonal matrix experiments, permanent magnet motors, stators.
In this paper an IoT application of LoRa is presented. The application is related to the so-called precision beekeeping. This term is associated with the monitoring of many variables within a hive and in its vicinity, which can assist the beekeeper at all the activities that have to be done in beekeeping practice. In order to achieve that kind of functionality the so called wireless sensor network has to be realized. First an overview of such technologies is given. Our decision was to take LoRa. The core of the system is an Arduino microcontroller with the addition of the LoRa shield. In the paper a process of communication between master and slave unit is described. In order to demonstrate the applicability, the slave unit has an additional temperature sensor attached. The system was verified by a successful temperature measurement lasting several days
A monolithic multi-hit digital TDC (time-to-digital converter) has been developed for the DUMAND 11 experiment. This TDC! has a 27 channel pipehed architecture, with a Ins least count.
The design of a micropower op amp suitable for biomedical applications is presented. A 1V battery is used for powering the circuit.The quiescent power consumption is under 303 PA. Current boosting is employed to achieve a maximal output swing very close to the power supply rails for low impedance loads.The input stage consists of PNP transistors in differential configuration. The gain stage is a common emitter amplifier with NPN transistors. And the output stage is a class AB amplifier with both NPN and PNP transistors driven by unique current amplifiers. -IntroductionThere is a demand for circuits powered by a single low voltage battery in biomedical applications. In analog world, silicon bipolar technology has an advantage over the field effect technologies. For equal size devices the transconductance of a bipolar transistor is an order of magnitude higher than for MOS or FET transistors. The bipolar base emitter quiescent voltage is close to 700 mV, which is physically the lowest limit of operation for bipolar circuits. Advanced MOS processes have threshold voltages around 700 mV. The quiescent voltage between gate and source must be higher in order to get a useful transconductance value. MOS devices operating in the diffusion conductivity region, below threshold voltage, have low, unstable transconductance values. If Schottky base emitter diodes were possible, they would preclude further reductions in power supply voltage. Some research in this direction exists. The problem with such a device would be the CH29645/91/0000-0274801.00 01991 IEEE very low transconductance values caused by low minority carriers injection from metal to silicon.Our work was supported as Rapid Prototyping.Therefore an analog array and standard bipolar process were used for qualification of the circuit architecture. -Design goalsThe circuit will be used in the audio range. This implies locating a second pole at approximately 25 KHz. Quiescent power consumption must be in order of 100 pW. Deliverable power to the load is in the order of 10 mW. Also, the minimum supply voltage is 800 mV. -Amplifier designThe circuit consists of four basic blocksdifferential input, gain stage, NPN output driver, PNP output driver and current source. Differential inputDifferential input is canonical in architecture.It consists of transistors Q5, Q6 and 47, Fig. 1.Because of a low noise criterion and a desire for a 0 V DC input voltage component, PNP transistors are used for achieving gain. The load resistances are passive in order to achieve a temperature independent differential stage. The DC temperature dependance of both the NPN and PNP transistors are given in Figs. 2,3. P N~N varies about 50 % from 0 to 70 degrees Celsius. The temperature dependence of PNPN is a result of the extremly high doping density in the emitter. This causes the emitter injection efficiency y to be a monotonous posistive function of temperature. In contrast, PNP transistors are more temperature stable. y and the 274
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