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Kirenol (1), darutoside (2), and darutigenol (3), which are major active diterpenoids isolated from Herba Siegesbeckiae, are reported for analgesic activity and inflammatory effects. Currently, in Vietnamese Pharmacopoeia V, there is no requirement for the contents of active ingredients in this medicinal plant. In this study, a high-performance liquid chromatography (HPLC) method, which was developed with good repeatability and recovery, was used for simultaneous quantification of 1, 2, and 3 in Herba Siegesbeckiae. This method was successfully applied to quantify 1-3 in samples of Herba Siegesbeckiae collected from different locations. The results showed that the content of compound 1 accounted for 0 – 5.77 mg/g, compound 2 ranged from 0.82 to 5.48 mg/g, and compound 3 ranged from 0.37 to 3.18 mg/g. These results are considered a reference for upgrading the specification and quality control of Herba Siegesbeckiae. Keywords: Herba Siegesbeckiae; kirenol; darutoside; darutigenol; HPLC.

The enhancement of the surface quality measures is still attracting great research attentions in electrical discharge machining. In the present investigation, an analysis was made to improve the surface performance measures in EDM process with different tool electrodes such as titanium, copper, and graphite electrodes under dielectric medium mixed with micro size titanium particles. The surface roughness, hardness, white layer thickness, crack formation, and surface topography were considered as surface quality measures. From the experimental investigation, it has been observed that surface hardness could be improved significantly with titanium powder-mixed dielectric medium due to its ability of changing conductivity of machining zone with copper tool electrode. The electrical and thermal conductivity of tool electrode and powder materials can strongly affect the quality of the machined surface in EDM process.

This paper studies local stability of a parametric optimal control problem governed by semilinear elliptic equations with mixed pointwise constraints. We show that if the unperturbed problem satisfies the strictly nonnegative second-order optimality conditions, then the solution map is upper Holder continuous in $$L^\infty $$ -norm of control variable.

This paper presents a study on optimum calculation of the exchanged diameter of grinding wheels in internal grinding of stainless steel. In this study, the effects of the grinding process parameters including the initial diameter, the total depth of dressing cut, the wheel life, the radial grinding wheel wear per dress and the ratio between the length and the diameter of the workpieces on the exchanged grinding wheel diameter were explored. The influences of cost factors including the machine tool hourly rate and the grinding wheel cost were also investigated. To evaluate the effects of these parameters on the optimum exchanged grinding wheel diameter, a simulation experiment was created and performed by and a computer program. A proposed model to determine the optimum exchanged grinding wheel diameter was given based on the results of the study.

This paper introduces a study on optimum determination of exchanged grinding wheel diameter when external grinding of stainless steel. In this study, the influences of grinding process parameters including the initial grinding wheel diameter, the total dressing depth, the radial grinding wheel wear per dress and the wheel life on the exchanged grinding wheel diameter were investigated. Also, the effect of cost parameters including the grinding wheel cost and the machine tool hourly rate were investigated. To estimate the influence of these parameters on the optimum exchanged grinding wheel diameter, a simulation experiment was designed and it was performed by a computer program. Based on the results of the experiment, a formula for calculation of the optimum exchanged diameter was introduced

Tool wear rate (TWR) in EDM has a direct effect on machining accuracy and production costs. Many new electrode materials have been introduced to improve TWR, and electrodes sprayed with refractory alloys are said to be new research directions with its prospects as well. In this study, the research team compared TWR of coated and uncoated electrodes in EDM for Ti-6AL-4 V titanium alloy. The basic electrode material is aluminum, and the coating material on the electrode surface is AlCrNi. Process parameters including current (I), gap volt (Vg), pulse on time (TON) were surveyed via Taguchi method. The results showed that TON and I are strongly influencing the TWR of both electrodes. The TWR of Al electrode is approximately 24% larger than that of coated Al electrode.

Fractional Frequency Reuse (FFR) is a promising to improve the spectrum e ciency in the LongTerm Evolution (LTE) cellular network. In the literature, various research works have been conducted to evaluate the performance of FFR. However, the presented analytical approach only dealt with the special cases in which the users are divided into 2 groups and only two power levels are utilised. In this paper, we consider a general case of FFR in which the users are classified intogroups and each group is assigned a serving power level. The mathematical model of the general FFR is presented and analysed through a stochastic geometry approach. The derived analytical results in terms of average coverage probability can covered all the related well-known results in the literature. Keywords: Fractional Frequency Reuse, LongTerm Evolution, coverage probability, stochastic geometry References [1] Cisco, Cisco visual networking index: Global mobile data traffic forecast update, 2015 - 2020, 2016. [2] A.S. Hamza, S.S. Khalifa, H.S. Hamza, K. Elsayed, A Survey on Inter-Cell Interference Coordination Techniques in OFDMA-Based Cellular Networks, IEEE Commun, Surveys & Tutorials 15(4) (2013) 1642-1670 [3] 3GPP TR 36.819 V11.1.0, Coordinated multi-point operation for LTE physical layer aspects, 2011. [4] 3GPP Release 10 V0.2.1, LTE-Advanced (3GPP Release 10 and beyond), 2014. [5] 3GPP TS 36.211 V14.1.0, E-UTRA Physical Channels and Modulation, 2016. [6] R. Ghaffar, R. Knopp, Fractional frequency reuse and interference suppression for ofdma networks, in: 8th International Symposium on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks, 2010, pp. 273-277. [7] Y. Kwon, O. Lee, J. Lee, M. Chung, Power Control for Soft Fractional Frequency Reuse in OFDMA System, Vol. 6018 of Lecture Notes in Comput.Science, Springer Berlin Heidelberg, 2010, book section 7 (2010) 63-71. [8] Enhancing LTE Cell-Edge Performance via PDCCH ICIC, in: FUJITSU NETWORK COMMUNICATIONS INC., 2011 [9] A.S. Hamza, S.S. Khalifa, H.S. Hamza, K. Elsayed, A Survey on Inter-Cell Interference Coordination Techniques in OFDMA-Based Cellular Networks, IEEE Commun, Surveys & Tutorials 15(4) (2013) 1642-1670. https://doi.org/10.1109/SURV.2013.013013.00028. [10] A. Busson1, I. Lahsen-Cherif2, Impact of resource blocks allocation strategies on downlink interference and sir distributions in lte networks: A stochastic geometry approach, Wireless Communications and Mobile Computing. [11] H. ElSawy, E. Hossain, M. Haenggi, Stochastic Geometry for Modeling, Analysis and Design of Multi-Tier and Cognitive Cellular Wireless Networks: A Survey, IEEE Commun, Surveys Tutorials 15(3) (2013) 996-1019. https://doi.org/10.1109/SURV.2013.052213.00000. [12] W. Bao, B. Liang, Stochastic Analysis of Uplink Interference in Two-Tier Femtocell Networks: Open Versus Closed Access, IEEE Trans, Wireless Commun. 14(11) (2015) 6200-6215. https://doi.org/10.1109/TWC.2015.2450216 . [13] H. Tabassum, Z. Dawy, E. Hossain, M.S. Alouini, Interference Statistics and Capacity Analysis for Uplink Transmission in Two-Tier Small Cell Networks: A Geometric Probability Approach, IEEE Trans, Wireless Commun 13(7) (2014) 3837-3852. [14] J.G. Andrews, F. Baccelli, R.K. Ganti, A tractable approach to coverage and rate in cellular networks, IEEE Transactions on Communications 59(11) (2011) 3122-3134. [15] Y. Lin, W. Bao, W. Yu, B. Liang, Optimizing User Association and Spectrum Allocation in HetNets: A Utility Perspective, IEEE J. Sel. Areas Commun. 33(6) (2015) 1025-1039. https://doi.org/10.1109/JSAC.2015.2417011. [16] M. Haenggi, Stochastic Geometry for Wireless Networks, Cambridge Univ, Press, November 2012. [17] H. ElSawy, E. Hossain, M. Haenggi, Stochastic Geometry for Modeling, Analysis and Design of Multi-Tier and Cognitive Cellular Wireless Networks: A Survey, IEEE Commun, Surveys Tutorials 15(3) (2013) 996-1019. [18] Huawei, R1-050507: Soft Frequency Reuse Scheme for UTRAN LTE, in: 3GPP TSG RAN WG1 Meeting #41, 2005. [19] M.A. Stegun, I.A., Handbook of Mathematical Functions with Formulas, Graphs and Mathematical Tables, 9th Edition, Dover Publications, 1972.