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71.
Pham Thanh Hue 《西部皮革》2018,(16)
越南太原省大慈县文安乡位于三岛国家公园管理处,社区居民生活困难,收入低,所以目前森林资源侵害状况依然存在。其中,25-50岁的群人对森林资源的影响最大,50岁以上和16岁以下的群人对森林资源的影响较小。人们对森林资源的影响是:伐木,狩猎动物,收集柴火,收集蔬菜,收集竹笋、药用植物。统计结果表明,天然林中具有18种树木经常被开发利用,常用木柴12种,药用29种,食用17种。7种动物经常被猎食。这些影响使得森林结构相当大改变,生物多样性减少,森林结构破坏。造成这种情况的主要原因是人们意识不高,缺乏工作机会,缺乏耕种土地,农业生产没有满足用户的需求。因此,必要有有关部门的协调在违法森林法的处理,为人民改善物质和精神生活,教育宣传和提高执法的认识 相似文献
72.
Pham Van Quyet Bernice Mei Jin Tan Celine Valeria Liew Lai Wah Chan Quan Sing Ng 《Drug development and industrial pharmacy》2018,44(4):624-631
L-NG-nitroarginine (LNNA), an analog of L-arginine, is a competitive inhibitor of nitric oxide synthase which causes the selective reduction of blood flow to tumor cells. Despite the potential of LNNA to function as an adjuvant in cancer therapies, its poor solubility and stability have hindered the development of an injectable formulation of LNNA that is suitable for human administration. This work, for the first time, details a systematic study on the determination of equilibrium Ka constants and the rate law of LNNA degradation. The four Ka values of LNNA were determined to be 1.03, 1.10?×?10?2, 2.51?×?10?10, and 1.33?×?10?13 M. From the kinetic and equilibrium studies, we have shown that the deprotonated form of LNNA is the main form of LNNA that undergoes degradation in aqueous media at room temperature. The rate law of LNNA degradation was found to be first order with respect to OH? concentration and first order with respect to LNNA? concentration. The rate constant at 25?°C and 1?atm was determined to be 0.04453 M?1min?1. A base catalyzed mechanism of LNNA degradation was proposed based on the kinetic study. The mechanism was found to be very useful in explaining the discrepancies and changes of the rate law at different pH values. It is thus recommended that LNNA should be formulated as a concentrated solution in acidic conditions for maximum chemical stability during storage and be diluted with a basic solution to near physiological pH just before administration. 相似文献
73.
Wireless Personal Communications - Cognitive radio networks (CRNs) have a shortcoming in that attackers can increase their ability to disturb secondary users (SUs). This paper focuses on jamming... 相似文献
74.
Journal of Computer Virology and Hacking Techniques - With macOS increasing popularity, the number, and variety of macOS malware are rising as well. Yet, very few tools exist for dynamic analysis... 相似文献
75.
Juan Xing Pham Van Hung Stephen Symons Muhammad Shahin David Hatcher 《Sensing and Instrumentation for Food Quality and Safety》2009,3(4):211-218
Sprout damage (pre-harvest germination) in wheat results in highly deleterious effects on end-product quality. Alpha-amylase,
the pre-dominant enzyme in the early stage of sprouting has the most damaging effect. This paper introduces a new method using
a SWIR hyperspectral imaging system (1000–2500 nm) to predict the α-amylase activity of individual wheat kernels. Two classes
of Canadian wheat, Canada Western Red Spring (CWRS) and Canada Western Amber Durum (CWAD), with samples of differing degrees
of sprout damage were investigated. Individual kernels were first imaged with the hyperspectral imaging system and then the
α-amylase activity of each kernel was determined analytically. Individual kernel α-amylase activity prediction was significant
(R
2 0.54 and 0.73) for CWAD and CWRS, respectively using Partial Least Square regression on the hyperspectral data. A classification
method is proposed to separate CWRS kernels with high α-amylase activity level from those with low α-amylase activity giving
an accuracy of above 80%. This work shows that hyper/multi-spectral imaging techniques can be used for rapidly predicting
the α-amylase activity of individual kernels, detecting sprouting at early stage. 相似文献
76.
Effect of ultrasound on removal of persistent organic pollutants (POPs) from different types of soils 总被引:2,自引:0,他引:2
Reena Amatya Shrestha Thuy Duong Pham Mika Sillanp 《Journal of hazardous materials》2009,170(2-3):871-875
A new and promising technology is utilization of sonochemistry on decontamination of polluted soil. The feasibility of this technology on treatment of contaminated soils (synthetic clay, natural farm clay, and kaolin) was studied by using two target persistent organic pollutants (POPs): hexachlorobenzene (HCB) and phenanthrene (PHE). The soils were highly contaminated in 500 mg/kg. The laboratory experiments were conducted with various conditions (moisture, power, and time duration). The effects of these parameters on ultrasonication (as well as the removal of contaminants) were examined. The reasonable moisture ratio of the slurry could be in range of 2:1–3:1. The process did not change pH values of soils. Experimental results showed that ultrasonication has a potential to reduce the high concentrations of these POPs. 相似文献
77.
This paper proposes the hybrid model of autoregressive moving average (ARMA) and generalized autoregressive conditional heteroscedasticity (GARCH) to estimate and forecast the machine state based on vibration signal. The main idea in this study is to employ the linear ARMA model and the nonlinear GARCH model to explain the wear and fault condition of machine, respectively. The successful outcomes of the ARMA/GARCH prediction model can give obvious explanation for future states of machine, which enhance the worth of machine condition monitoring as well as condition-based maintenance in practical applications. The advance of the proposed model is verified in empirical results as applying for a real system of a methane compressor in a petrochemical plant. 相似文献
78.
We are given a trajectory
T\mathcal{T}
and an area
A\mathcal{A}
.
T\mathcal{T}
might intersect
A\mathcal{A}
several times, and our aim is to detect whether
T\mathcal{T}
visits
A\mathcal{A}
with some regularity, e.g. what is the longest time span that a GPS-GSM equipped elephant visited a specific lake on a daily
(weekly or yearly) basis, where the elephant has to visit the lake most of the days (weeks or years), but not necessarily on every day (week or year). 相似文献
79.
This article analyzes the dynamics of motion of various setups of two multiple degree‐of‐freedom (DOF) fingers that have soft tips, in fine manipulation of an object, and shows performances of their motions via computer simulation. A mathematical model of these dynamics is described as a system of nonlinear differential equations expressing motion of the overall fingers‐object system together with algebraic constraints due to tight area contacts between the finger‐tips and surfaces of the object. First, problems of (1) dynamic, stable grasping and (2) regulation of the object rotational angle by means of a setup of dual two‐DOF fingers, are treated. Second, the problem of regulating the position of the object mass center by means of a pair of two‐DOF and three‐DOF fingers is considered. Third, a set of dual three‐DOF fingers is treated, in order to let it perform a sophisticated task, which is specified by a periodic pattern of the object posture and a constant internal force. In any case, there exist sensory‐motor coordinations, which are described by analytic feedback connections from sensing to actions at finger joints. In the cases of setpoint control problems, convergences of motion to secure grasping together with the specified object rotational angle and/or the specified object mass center position, are proved theoretically. A constraint stabilization method (CSM) is used for solving numerically the differential algebraic equations to show performances of the proposed sensory‐feedback schemes. © 2002 Wiley Periodicals, Inc. 相似文献