A Bio-Diesel Chemical Kinetic Mechanism Based on Decoupling Methodology and Detailed H2/O2/CO/C1~C3 Mechanism

Biodiesel is a renewable, clean-burning diesel replacement, and may have superior brake thermal efficiency with certain blends compared to traditional diesel counterpart at higher compression ratios. The combustion chemistry process of biodiesel, which has not been well understood, is of great interests to some engine researchers. Researchers have developed some complicated chemical kinetic mechanisms for bio-diesel, which cannot be used in engine CFD (computational fluid dynamics) with current computational resources. The present work aims to construct a new chemical kinetic mechanism with a medium size for biodiesel combustion. Since 2016, H2/O2/CO/C1 and C2-C3 detailed sub-mechanisms (the C3 model contained in AramcoMech2.0) have been developed for accurately predicting laminar flame speeds, ignition delay times, and important species evolutions, and have been validated against a large array of experimental measurements over a wide range of conditions. In this paper, a 3-component biodiesel surrogate chemical kinetic mechanism constructed in 2015 based on decoupling methodology has been combined with the new “core” H2/O2/CO/C1~C3 detailed mechanism to generate a new bio-diesel chemical kinetic mechanism. In the surrogate mechanism construction, three skeletal sub-mechanisms are used for the three biodiesel components (MD (methyl decanoate), MD5D (methyl-5-decenoate), and n-decane). The final mechanism, which has 183 species and 1002 reactions, has been validated with available experiment data. It will be validated extensively with more experimental biodiesel data and applied to engine CFD for understanding biodiesel combustion

Wavelet packet decomposition-based fault diagnosis scheme for SRM drives with a single current sensor

Power converters are a key, but vulnerable component in switched reluctance motor (SRM) drives. In this paper, a new fault diagnosis scheme for SRM converters is proposed based on the wavelet packet decomposition (WPD) with a dc-link current sensor. Open- and short-circuit faults of the power switches in an asymmetrical half-bridge converter are analyzed in details. In order to obtain the fault signature from the phase currents, two pulse-width modulation signals with phase shift are injected into the lower-switches of the converter to extract the excitation current, and the WPD algorithm is then applied to the detected currents for fault diagnosis. Moreover, a discrete degree of the wavelet packet node energy is chosen as the fault coefficient. The converter faults can be diagnosed and located directly by determining the changes in the discrete degree from the detected currents. The proposed scheme requires only one current sensor in the dc link, while conventional methods need one sensor for each phase or additional detection circuits. The experimental results on a 750-W three-phase SRM are presented to confirm the effectiveness of the proposed fault diagnosis scheme

Chemical composition and product quality control of turmeric (Curcuma longa L.)

Chemical constituents of various tissues of turmeric (Curcuma longa L.) have been extensively investigated. To date, at least 235 compounds, primarily phenolic compounds and terpenoids have been identified from the species, including 22 diarylheptanoids and diarylpentanoids, eight phenylpropene and other phenolic compounds, 68 monoterpenes, 109 sesquiterpenes, five diterpenes, three triterpenoids, four sterols, two alkaloids, and 14 other compounds. Curcuminoids (diarylheptanoids) and essential oils are major bioactive ingredients showing various bioactivities in in vitro and in vivo bioassays. Curcuminoids in turmeric are primarily accumulated in rhizomes. The essential oils from leaves and flowers are usually dominated by monoterpenes while those from roots and rhizomes primarily contained sesquiterpenes. The contents of curcuminoids in turmeric rhizomes vary often with varieties, locations, sources, and cultivation conditions, while there are significant variations in composition of essential oils of turmeric rhizomes with varieties and geographical locations. Further, both curcuminoids and essential oils vary in contents with different extraction methods and are unstable with extraction and storage processes. As a result, the quality of commercial turmeric products can be markedly varied. While curcumin (1), demethoxycurcumin (2), and bisdemethoxycurcumin (5) have been used as marker compounds for the quality control of rhizomes, powders, and extract (“curcumin”) products, Ar-turmerone (99), -turmerone (100), and -turmerone (101) may be used to control the product quality of turmeric oil and oleoresin products. Authentication of turmeric products can be achieved by chromatographic and NMR techniques, DNA markers, with morphological and anatomic data as well as GAP and other information available

Pharmaceutical Crops: An Overview

Pharmaceutical crops is an ambiguous term used by biologists and chemists for different categories of plants. We define pharmaceutical crops as those cultivated species that are used for extraction or preparation of therapeutic substances such as active pharmaceutical ingredients (APIs), excipients used in pharmaceutical formulations, vaccines and antibodies, as well as other therapeutic proteins. Based on the type of pharmaceutical product, these crops can be classified into three distinct yet sometimes overlapping categories: crops for the production of small therapeutic molecules (STMs), large therapeutic molecules (LMTs), or standard therapeutic extracts (STEs). This review briefly discusses the relationships of pharmaceutical crops with traditional food crops, medicinal plants, medicinal crops, and invasive species. It also addresses the importance, advantages, problems, and challenges of research and development of pharmaceutical crops. This article references the plant specimen Nyssaceae, Camptotheca lowreyana, currently found in the lab of the National Center for Pharmaceutical Crops

Independent current control of dual parallel SRM drive using a public current sensor

Switched reluctance motors (SRMs) have been considered a potential candidate for automotive applications due to its rare-earth-free feature and wide speed range. Conventionally, a current sensor is installed in each phase for the current regulation control, which will considerably add the cost and volume to multimotor drives. This paper proposes an independent current control technique for dual parallel SRM drives using only one current sensor. In order to identify the individual motor currents from the public current, a pulse injection scheme is developed accordingly. Two pulses are individually injected into the lower transistors of the dual converter in the excitation regions and the fixed current sampling points triggered by the injected pulse are presented for motor current identification. The independent current control for the dual SRM can be directly implemented by the public current sensing, although the motor parameters are different. The developed system requires only one current sensor without additional hardware or reduced system performance. The simulation and experimental results on parallel 750 W and 150 W three-phase 12/8 SRM drives are presented to confirm the effectiveness of the proposed method. With this scheme, the dual-motor drive can be more compact and cost effective for traction drive applications

Investigation of skewing effects on the vibration reduction of three-phase switched reluctance motors

Switched reluctance motors (SRMs) are gaining in popularity because of their robustness, low cost, and excellent high-speed characteristics. However, they are known to cause vibration and noise primarily due to the radial pulsating force resulting from their double-saliency structure. This paper investigates the effect of skewing the stator and/or rotor on the vibration reduction of the three-phase SRMs by developing four 12/8-pole SRMs, including a conventional SRM, a skewed rotor-SRM (SR-SRM), a skewed stator-SRM (SS-SRM), and a skewed stator and rotor-SRM (SSR-SRM). The radial force distributed on the stator yoke under different skewing angles is extensively studied by the finite-element method and experimental tests on the four prototypes. The inductance and torque characteristics of the four motors are also compared, and a control strategy by modulating the turn-ON and turn-OFF angles for the SR-SRM and the SS-SRM are also presented. Furthermore, experimental results validate the numerical models and the effectiveness of the skewing in reducing the motor vibration. Test results also suggest that skewing the stator is more effective than skewing the rotor in the SRMs