A geometric process model for M/PH(M/PH)/1/K queue with new service machine procurement lead time

In this article, we consider a geometric process model for M/PH(M/PH)/1/K queue with new service machine procurement lead time. A maintenance policy (N???1,?N) based on the number of failures of the service machine is introduced into the system. Assuming that a failed service machine after repair will not be ‘as good as new’, and the spare service machine for replacement is only available by an order. More specifically, we suppose that the procurement lead time for delivering the spare service machine follows a phase-type (PH) distribution. Under such assumptions, we apply the matrix-analytic method to develop the steady state probabilities of the system, and then we obtain some system performance measures. Finally, employing an important Lemma, the explicit expression of the long-run average cost rate for the service machine is derived, and the direct search method is also implemented to determine the optimal value of N for minimising the average cost rate.     

Synthesis and characterization of magnetic bioactive glass-ceramics containing Mg ferrite for hyperthermia

Novel magnetic bioactive glass-ceramics (M GC) were synthesized by doping Mg ferrite to wollastonite–fluorapatite-containing glass-ceramics. The phase composition was investigated by XRD. The magnetic property was measured by VSM. The in vitro bioactivity was investigated by simulated body fluid (SBF) soaking experiment. Cell growth on the surface of the material was evaluated by co-culturing osteoblast-like ROS17/2.8 cells with M GC. The results showed that CaSiO₃, Ca₂MgSi₂O₇, Ca₅(PO₄)₃F and Fe₂MgO₄ were the main phases of M GC. Under a magnetic field of 10,000 Oe, the saturation magnetization and coercive force of M GC were 7.2 emu/g and 175 Oe, respectively. After soaking in SBF for 14 days, a lot of hydroxyapatite containing CO₃^2? was observed on the surface of M GC. The experiment of co-culturing cells with M GC showed that osteoblast-like ROS17/2.8 cells could attach well on the surface of M GC. The material has the potential to be used as thermoseeds for hyperthermia.     

Neurofeedback Treatment of College Students' Test on Anxiety, Depression, Personality, and Mood

Biofeedback is used to treat the mental diseases of college students, such as test anxiety, depression, personality, and mood. Anxiety of the colleague students was first tested by test anxiety scale （TAS） and then treated by biofeedback. After getting the biofeedback treatment, the students＇ TAS scores, blood volume pulse, and skin conductance were decreased, especially, their TAS scores dropped markedly. Meanwhile, the level of EEG （61 rhythm/a rhythm） and peripheral temperature increased observably. Then, neurofeedbaek （β1 rhythm/α rhythm） was applied to treat students＇ depression, personality, and mood. As a result, these three kinds of symptoms got alleviated. And their therapeutic effects based on neurofeedback were more stable, durative and less reerudescent.     

塔里木沙漠公路沿线地下水流速流向测定

本文在沿塔里木沙漠公路设置的监测井中,利用日本Alec Electronics公司生产的MODELGFD4型地下水流向流速计,对塔克拉玛干沙漠腹地的地下水流速流向作了一次测定,结果显示：沙漠公路沿线地下水平均流速为：0．01cm／min,即52．56m／a;地下水流动方向在沙漠北部主要以ENE方向为主,沙漠中部除个别井点外主要以EN方向为主,沙漠南部尼雅河下游监测井中流向由ENN方向和WNN方向构成,牙通古斯河下游观测井处以ESS方向为主。地下水流动方向的控制因素主要有：盆地总体地形因素、河流流量变化、局部地形因素。     

IPSec VPN与防火墙协同工作的系统设计与实现

IPSec VPN和防火墙为网络的安全做出了重大贡献.采用IPSec VPN技术不仅可实现数据在公网中安全传输,还可在一定程度上保护内网安全;防火墙所完成的任务是保护网络不受非法的"入侵".当IPSec VPN与防火墙同时共存于同一系统中时需考虑两者的协同工作问题.文中提出了并实现了一种基于虚拟网卡技术的IPSec VPN系统.将虚拟网卡与IPSecVPN相结合的系统可有效实现IPSec VPN与内网防火墙协同工作.     

基于串空间模型的WAI密钥协商协议分析

WAPI实施方案中采用WAI(WLAN Authentication Infrastructure)协议来进行密钥协商,运用串空间模型分析验证了WAI协议中的单播密钥协商协议的实施方案,指出该实施方案较之原方案,安全性有了较大的提高.同时,利用该协议STA以及AP能够实现双向身份认证,并能安全地协商到会话密钥.     

Poly(N-vinyl-2-pyrrolidone)-stabilized ruthenium supported on bamboo leaf-derived porous carbon for NH3BH3 hydrolysis

In this work, poly(N-vinyl-2-pyrrolidone) (PVP)-stabilized ruthenium nanoparticles (NPs) supported on bamboo leaf-derived porous carbon (Ru/BC) has been synthesized via a one-step procedure. The structure and morphology of the as-synthesized samples were characterized by means of X-ray diffraction (XRD), X-ray photoelectron spectrometry (XPS), scanning electron microscope (SEM) and transmission electron microscope (TEM). As a catalyst for hydrogen generation from the hydrolysis of ammonia-borane (AB, NH₃BH₃) at room temperature, Ru/BC stabilized with 1 mg of PVP exhibited high activity (TOF = 718 mol_H2·mol_Ru⁻¹·min⁻¹) and low activation energy (E_a = 22.8 kJ mol⁻¹). In addition, the catalyst could be easily recovered and showed fairly good recyclability with 55.6% of the initial catalytic activity retained after ten experimental cycles, which confirmed that PVP could stabilize the Ru NPs and prevent their agglomeration on BC surface. Our results suggest that PVP-stabilized Ru/BC is a highly efficient catalyst for the hydrolysis of AB.     

黄山贡菊花成分测定及茶饮料开发前景展望

黄山贡菊花主产于安徽省黄山风景区,为菊科植物,在饮用与药用方面具有很高的价值,但其成分却鲜为人知。在对菊科植物成分进行实验分析的基础上,定性测定了黄山贡菊所含的多种成分。针对国内外以黄山贡菊花为主要原料的饮料甚少的情况,拟开发一种以黄山贡菊花为主要成分的饮料,并简要分析了该饮品的市场前景。     

Facile synthesis of PdAu/C by cold plasma for efficient dehydrogenation of formic acid

Decomposition of formic acid biomass to generate hydrogen is vital for coping with fossil energy depletion, environmental pollution, and developing clean, efficient, safe, and sustainable modern energy system. In this study, a PdAu/C−C bimetallic catalyst was prepared by the co-impregnation method followed by an atmospheric pressure (AP) cold plasma treatment to synthesize PdAu/C−P catalysts. The resulting PdAu/C−P showed excellent catalytic activity for the formic acid dehydrogenation (FAD) reaction. The total volume of H₂ and CO₂ released from the FAD reaction was about 375 mL after 4 h at 50 °C, and the initial turnover frequency (TOF_initial) was 808.6 h⁻¹. We used X−ray diffractometry (XRD), temperature programmed reduction (TPR) and high-resolution transmission electron microscopy (HRTEM) to show that plasma can effectively promote the redispersion of Pd−Au particles on the surface of the support. The average particle size of PdAu/C−P (3.5 ± 1.5 nm) was less than PdAu/C−C (4.4 ± 1.9 nm) and uniformly distributed. X-ray photoelectron spectroscopy (XPS), TPR, and HRTEM showed that PdAu/C−P has a higher degree of alloying. In addition, the strong electric field in the plasma facilitated more metal sites located on the outer surface of the support in PdAu/C−P, and the atomic ratio of M/C (M = Pd and Au) (0.0134) was much larger than that of PdAu/C−C (0.0060). The apparent activation energy (E_a) of PdAu/C−P for the FAD reaction was only 27.25 kJ mol⁻¹, and it had much higher activity and stability than the commercial Pd/C (Sigma−Aldrich). The total volume of H₂ and CO₂ produced over the PdAu/C−P for three cycles was 1.33, 5.87, and 8.56 times that of commercial Pd/C. Overall, the cold plasma enhanced the degree of alloying, promoted the redispersion of agglomerated particles, and regulated the surface enrichment of the active metal components. This is of great significance for guiding the preparation of high−performance multi-metal catalysts by cold plasma.     

Bimetallic PdAu catalysts for formic acid dehydrogenation

A series of monometallic and bimetallic palladium gold catalyst were prepared and studied for the formic acid dehydrogenation reaction. Different Pd/Au compositions were employed (Pd_xAu_100-x, where x = 25; 50 and 75) and their impact on alloy structure, particle size and dispersion was evaluated. Active phase composition and reaction parameters such as temperature, formic acid concentration or formate/formic acid ratio were adjusted to obtain active and selective catalyst for hydrogen production. An important particle size effect was observed and related to Pd/Au composition for all bimetallic catalysts.