Research on Evaluation Technology of Low Temperature Cold Start Performance of Hydraulic Oil

In order to comprehensively test the low temperature cold start performance of hydraulic oil and ensure their use effectiveness to the fullest, the idea of low temperature cold start performance index is proposed, so as to comprehensively evaluate the low temperature capability. Firstly, the cold start performance index system of hydraulic oil tested in low temperature environment is constructed, so as to describe its low temperature capability from multiple angles and in a comprehensive manner; secondly, for different index types, the corresponding data collection methods and data analysis methods are clarified, and the low temperature cold start performance of hydraulic fluid is evaluated. Finally, using the method as an example for three oils, the index types and assessment results are given to further illustrate the scientific nature of the research method. The research content can provide some technical support for the evaluation of the low temperature cold starting performance test of hydraulic winches.

A Fundamental Thermodynamic Investigation of Compression Ratio Effects in Relation to Diesel Engine Size

In this study, a fundamental generalized thermodynamic model of internal combustion engines was applied to evaluate engine compression ratio effects principally in relation to engine size. Performance and efficiency metrics were investigated systematically. Further, cylinder wall temperature was varied across a range of cold start to stabilized operating temperatures. A very broad range of engine bore sizes and bore-to-stroke ratios were evaluated, representing small to large diesel engines in service. In general, it was observed that engine efficiency increases moderately with increasing compression ratio and bore size. Additionally, surface area-to-volume ratio is a critical metric when evaluating various size engines. This leads to greater relative heat transfer in the smaller bore engines with higher compression ratios. The sensitivity to heat losses is also much greater in the smaller engines. Smaller engines with higher compression ratios are expected to be most affected by cold starting conditions. Exhaust enthalpy is highest for larger bore engines with lower compression ratios, an important consideration for engine boosting. Higher convective heat transfer coefficients are also expected in smaller bore engines with higher compression ratios due to the higher operating pressures.

Impact of damaging and recovery on the temperature dependence of the work function of oxide electrodes in fluorescent lamps

In the present work the work function of electrons for oxide cathodes in operating fluorescent lamps is measured before and after damaging the cathodes by cold starting of the lamp. A strong increase of the absolute value and a decrease of the temperature dependence of the work function is observed. The values recover partly after operating the lamp for a certain time. The results are interpreted as the consequence of a thin metallic layer generated during cold starting at the surface of the oxide and its effect on the depletion of electrons of donor-like colour centres (appearing in the oxide due to oxygen vacancies) under the ultraviolet radiation present in an operating fluorescent lamp, and on the magnitude and temperature dependence of the work function in the plated regions, invoking the patch effect to generate an averaged value of the work function, which is then assumed to be observed experimentally. Moreover, barium surface states are considered, yielding reasonable values for the not plated regions, when calculating the work function, as well for the assumption of a depletion of also these states by ultraviolet radiation, as also when only regarding a thermal excitation of the surface states applying the Fowler equation. Finally, a model of a diffusion governed dynamical equilibrium yielding a T3∕2 dependence for the donor concentration is proposed.

Domain based Chunking

Chunking means splitting the sentences into tokens and then grouping them in a meaningful way. When it comes to high-performance chunking systems, transformer models have proved to be the state of the art benchmarks. To perform chunking as a task it requires a large-scale high quality annotated corpus where each token is attached with a particular tag similar as that of Named Entity Recognition Tasks. Later these tags are used in conjunction with pointer frameworks to find the final chunk. To solve this for a specific domain problem, it becomes a highly costly affair in terms of time and resources to manually annotate and produce a large-high-quality training set. When the domain is specific and diverse, then cold starting becomes even more difficult because of the expected large number of manually annotated queries to cover all aspects. To overcome the problem, we applied a grammar-based text generation mechanism where instead of annotating a sentence we annotate using grammar templates. We defined various templates corresponding to different grammar rules. To create a sentence we used these templates along with the rules where symbol or terminal values were chosen from the domain data catalog. It helped us to create a large number of annotated queries. These annotated queries were used for training the machine learning model using an ensemble transformer-based deep neural network model [24.] We found that grammar-based annotation was useful to solve domain-based chunks in input query sentences without any manual annotation where it was found to achieve a classification F1 score of 96.97% in classifying the tokens for the out of template queries.

A self-powered ultra-low-power intermittent-control SSHI circuit for piezoelectric energy harvesting

Purpose Existing control circuits for piezoelectric energy harvesting (PEH) suffers from long startup time or high power consumption. This paper aims to design an ultra-low power control circuit that can harvest weak ambient vibrational energy on the order of several microwatts to power heavy loads such as wireless sensors. Design/methodology/approach A self-powered control circuit is proposed, functioning for very brief periods at the maximum power point, resulting in a low duty cycle. The circuit can start to function at low input power thresholds and can promptly achieve optimal operating conditions when cold-starting. The circuit is designed to be able to operate without stable DC power supply and powered by the piezoelectric transducers. Findings When using the series-synchronized switch harvesting on inductor circuit with a large 1 mF energy storage capacitor, the proposed circuit can perform 322% better than the standard energy harvesting circuit in terms of energy harvested. This control circuit can also achieve an ultra-low consumption of 0.3 µW, as well as capable of cold-starting with input power as low as 5.78 µW. Originality/value The intermittent control strategy proposed in this paper can drastically reduce power consumption of the control circuit. Without dedicated cold-start modules and DC auxiliary supply, the circuit can achieve optimal efficiency within one input cycle, if the input signal is larger than voltage threshold. The proposed control strategy is especially favorable for harvesting energy from natural vibrations and can be a promising solution for other PEH circuits as well.

Problems with glow plug – a review

Despite the development of hybrid and electric vehicles, a many-million population of cars with combustion engines, and particularly CI engines occurs on the roads. Also, many stationary CI engines are still utilized. Despite their improved technologies and characteristics the modern CI engines negatively affect an environment due to cold starting problems. Below 0 °C, engine starts are problematic due to the decreased battery performance and the spray characteristics, the increased ignition delay time, and the engine oil viscosity. Therefore, various glow plugs are applied to facilitate this process. Types, features, and applications of glow plugs in various engines have been discussed in the paper. One case of failure of glow plug has been presented in the article, including the cause of it.