串级变比值调节在湿法磷肥微机控制系统中的应用

串级变比值调节在湿法磷肥微机控制系统中的应用钱晓贵ＡｐｐｌｉｃａｔｉｏｎｏｆＣａｓｃａｄｅＶａｒｉａｂｌｅ－ＲａｔｉｏＲｅｇｕｌａｔｉｏｎｉｎＭｉｃｒｏｃｏｍｐｕｔｅｒＣｏｎｔｒｏｌＳｙｓｔｅｍｏｆＷｅｔＰｈｏｓｐｈａｔｅＦｅｒｔｉｌｉｚｅｒ￥Ｑｉａ...

变比值控制在加热炉中的应用浅析

加热炉燃烧控制系统最重要的任务是保持加热炉的负载导热油温度稳定.当负载量改变,通过调节燃料量(或送风量),从而改变炉膛发热量,最终使负载温度稳定.其次,我们应该保证燃料的经济燃烧,既不能因为空气不足而冒黑烟,也不能因为空气过多而导致热量损失增加.所以燃料量和空气量应保持一定的比例,或者说烟气中的氧气浓度应保持在一定的值.

变比值控制在加热炉中的应用浅析

加热炉燃烧控制系统最重要的任务是保持加热炉的负载导热油温度稳定.当负载量改变,通过调节燃料量(或送风量),从而改变炉膛发热量,最终使负载温度稳定.其次,我们应该保证燃料的经济燃烧,既不能因为空气不足而冒黑烟,也不能因为空气过多而导致热量损失增加.所以燃料量和空气量应保持一定的比例,或者说烟气中的氧气浓度应保持在一定的值.

一个面积问题的推广及应用

本文推广了一个面积问题 ,并利用推广的结论 ,解决了一些有关问题。

A Class of Nonlocal Boundary Value Problems for Elliptic Systems in Unbounded Domains

A class of nonlocal boundary value probl em s for elliptic systems in the unbounded domains are considered. Under suitable c onditions, the existence of solution and the comparison theorem for the boundary value problems are studied.

Accurate and precise determination of lead isotope composition in selected geochemical reference materials

Lead(Pb)isotopes have been extensively employed in tracing sources of Pb and its transport pathways through the environment.However,Pb isotopic ratios in related geochemical reference materials are scarce.Here,we report high-precision Pb isotopic ratios measured by Nu Plasma II MC-ICP-MS using calibrated ^(205)Tl/^(203)Tl=2.38865(NIST SRM 997)for mass discrimination correction.The long-term external precision(2SD)for NISTSRM 981 of Pb,BCR-2,and BHVO-2 are 0.31‰(n=105),0.42‰(n=11),and 0.25‰(n=5)for ^(208)Pb/ ^(206)Pb and 0.16‰,0.53‰,and 0.07‰for ^(206)Pb/ ^(207)Pb,both respectively,and their Pb isotopic ratios are in excellent agreement with the recommended values.Using this method,we report for the first time Pb isotopic compositions in shale SGR-1b(USGS);coal CLB-1(USGS);stream sediments GSD-17,-21,and-23(IGGE);soils GSS-12,-13,-14,-15,and-16(IGGE);plants GSV-1,-2,and-3(IGGE);and human hair GSH-1(IGGE).

物理研究方法在初中教材中的实施和运用

物理研究方法是过程与方法中的基本要素，是能力培养的具体要求。掌握研究方法是从物理到生活的深化，是学生可持续发展的源动力。初中物理研究方法主要有控制变量法、转换法，累积放大法、理想模型法、科学推理法、类比法、比较法、比值定义法、逆向思维法等九种方法。各种方法在教材中的实施与运用，是教学过程中的重点目标。

Trophic ecology of small yellow croaker (Larimichthys polyactis Bleeker): stable carbon and nitrogen isotope evidence

The trophic ecology of the small yellow croaker （Larimichthys polyactis） was studied using stable isotope analyses. Samples were collected from July to September 2009 and 34 individuals from eight sites were examined for stable carbon and nitrogen isotopes. Stable carbon isotope ratios （~3C） ranged from -20.67 to -15.43, while stable nitrogen isotope ratios （~SN） ranged 9.18-12.23. The relationship between fi^3C and ~SN suggested high resource partitioning in the sampling area. Significant differences in stable isotope values among the eight sampling sites may be linked to environmental diversities involving various physical processes （such as ocean current, wind and tide） and different carbon sources. Furthermore, the stable isotope ratios may also explain the ontogenetic variability in diet and feeding, because δ13C and δ15N varied significantly with increasing body size. The findings are consistent with other studies on diet analyses in small yellow croaker. It was also demonstrated that stable isotope analysis could be used to estimate the trophic characters of small yellow croaker in feeding patterns and migrating habits.

Adsorption of Orange II Dye using Activated Carbon Produced from Iraqi Date-Palm Stones

A synthetic activated carbon was manufactured from date-palm stones using zinc chloride, cadmium chloride and sodium chloride at different temperatures and atmospheres. Specific surface area, RC and pH were measured and the activated carbon was used to absorb the orange II dye. Adsorption equilibrium was also studied, and it was found that the adsorption process on the synthetic activated carbon fit very well with the Langmuir isotherm model and less fit with Freundlich isotherm model. The specific surface area was highly affected by increasing temperature of combustion while the atmosphere of combustion had a little effects on surface area. The results showed that the atmosphere and temperature had no such effect on RC values. However, the RC of zinc chloride samples gave the highest values compared to that of cadmium chloride or sodium chlorides. The values of pH indicated an acid medium for cadmium chloride to alkali medium for sodium chloride, while the samples of zinc chloride showed a neutral medium.

Development of a New Dynamic Lightweight Penetrometer for the Determination of Mechanical Properties of Fine-Grained Soils

Dynamic cone penetrometer is mainly used as an in situ device and laboratory application, in a mould, has rarely been reported due to the confining effect. In this study, a dynamic lightweight cone penetrometer that can be used in a CBR （California bearing ratio） mould in the laboratory as well as in the field, with similar results, was developed. The results show that the influence of the mould confinement can be eliminated when the hammer mass is 2.25 kg. A strong correlation was found between CBR values and the new dynamic lightweight penetrometer index, for six fine-grained soil samples, with different moisture contents, used in this study.

Application of Bifurcation Analysis on Active Distribution Systems

This paper presents the application of bifurcation method on the steady state three-phase load-flow Jacobian method to study the voltage stability of unbalanced distribution systems. The eigenvalue analysis is used to study distribution system behavior under different operating conditions. Two-bus connected by asymmetrical line is used as the study system. The effects of both unbalance and extreme loading conditions are investigated. Also, the impact of distributed energy resources is studied. Different case studies and loading scenarios are presented to trace the eigenvalues of the Jacobian matrix. The results exhibit the existence of a new bifurcation point which may not be related to the voltage stability.

硝酸生产过程中氧化反应的控制方案探讨

在硝酸生产氨氧化反应中需对氨气和空气流量进行稳定的比值控制,对实际运用中可采取的多种比值控制方式作出介绍,对组态中的系数确定作了详细推导,归纳了其应用特点,并给出了逻辑提降实现的方法。

A NEW LAPLACIAN COMPRISON THEOREM AND THE ESTIMATE OF EIGENVALUES

This paper establishes a new Laplacian comparison theorem which is specially useful tothe mathelds of nonpositive curvature. It leads naturally to the corresponding heat kernelcomparison and eigenvalue comparison theorems. Furthermore, a lower estimate of L2-spectrumof an n-dimensional non-compact complete Cartan-Hadamard manifold is given by (n-1)k/4,provided its mRicci curvature -(n -1)k (k= const. 0).

Eigenvalue Comparison Theorems on Finsler Manifolds

Cheng-type inequality, Cheeger-type inequality and Faber-Krahn-type inequality are generalized to Finsler manifolds. For a compact Finsler manifold with the weighted Ricci curvature bounded from below by a negative constant, Li-Yau's estimation of the first eigenvalue is also given.

Distribution of stable carbon isotope in coalbed methane from the east margin of Ordos Basin

The commercial recovery of methane from coal is well established in the coalbed methane(CBM) blocks at the east margin of Ordos Basin, China. CBM forms with various carbon isotopic ratios(δ13CPDB) due to the carbon isotopic fractionation in biogenical or thermogenical processes. Based on the geologic evolution of coalbed reservoir and studies on the characteristics of δ13 CPDB values distributed spatially(e.g., horizontal CBM well location area, vertical coal burial zone, coal rank, etc.) and temporally(e.g., geologic evolution history), we explored the formation mechanism of carbon isotopic of methane. The relatively low δ13 CPDB values are widely distributed along the research area, indicating a trend of "lighter-heavier-lighter" from north to south. From a combination analysis of the relationship between δ13 CPDB and the relative effects, the essential aspects in determining CBM carbon isotope being light in the study area are: the genesis of secondary biogas in the north; water soluble effects in the active hydrodynamic areas in the middle; desorption fractionation effect promoted by tectonic evolution in the south; and the sudden warming hydrocarbon fractionation accelerated by magmatic event in particular areas(e.g., Linxian).

Maximization of the sum of the trace ratio on the Stiefel manifold, I: Theory

We are concerned with the maximization of tr（V T AV）/tr（V T BV）＋tr（V T CV） over the Stiefel manifold {V ∈ R m×l ｜ V T V = Il} （l 〈 m）, where B is a given symmetric and positive definite matrix, A and C are symmetric matrices, and tr（. ） is the trace of a square matrix. This is a subspace version of the maximization problem studied in Zhang （2013）, which arises from real-world applications in, for example, the downlink of a multi-user MIMO system and the sparse Fisher discriminant analysis in pattern recognition. We establish necessary conditions for both the local and global maximizers and connect the problem with a nonlinear extreme eigenvalue problem. The necessary condition for the global maximizers offers deep insights into the problem, on the one hand, and, on the other hand, naturally leads to a self-consistent-field （SCF） iteration to be presented and analyzed in detail in Part II of this paper.

Rigid Properties of Quasi-almost-Einstein Metrics

In this paper,quasi-almost-Einstein metrics on complete manifolds are studied.Two examples are given and several formulas are established.With the help of these formulas,the author proves rigid results on compact or noncompact manifolds,in which some basic tools,such as the weighted volume comparison theorem and the weak maximum principle at infinity,are used.A lower bound estimate for the scalar curvature is also obtained.

Gap results for compact quasi-Einstein metrics

In this paper, we work on compact quasi-Einstein metrics and prove several gap results. In the first part, we get a gap estimate for the first nonzero eigenvalue of the weighted Laplacian, by establishing a comparison theorem for the weighted heat kernel. In the second part, we establish two gap results for the Ricci curvature and the scalar curvature, based on which some rigid properties can be derived.

bPermian, Lopingian, strontium isotopic ratio, conodont zone, marine carbonate, stable isotope chemostratigraphy

The Lopingian is one of the fastest rising periods of seawater strontium isotopic ratios （^87Sr/^86Sr） in earth history, and its mechanisms and increasing rates of the ^87Sr/^86Sr evolution were still disputed widely. These disputations among researchers were caused mainly by timeframe selection （sections＇ thickness or data of radiometric ages）, and different stratigraphic boundaries and un-upmost dated ages. This paper examined published ^87Sr/^86Sr data of the Lopingian, and projected them on timescales based on evolutionary and age constrained conodonts fossils. ^87Sr/^86Sr evolution vs fossil constraining timescales was re-established in this period. This research suggests： （1） ^87Sr/^86Sr excursion projects on fossil zones can truly support ^87Sr/^86Sr evolutionary pattern in the period; （2） ^87Sr/^86Sr evolution provides a new approach for stratigraphic research of marine carbonate sections in lieu of biostratigraphic data; （3） ^87Sr/^86Sr stratigraphy works on marine carbonate sections of different sedimentation rates even between different basins; （4） the ^875r/^86Sr data and its shift was dependent on samples materials and chemical treatment methods; （5） the increasing rate of marine water ^875r/^86Sr in the Late Permian is suggested as 5.4× 10^-5/Ma or slightly lower; （6） sedimentation age and its ^875r/^86Sr of the Lopingian marine carbonate suggested as： Dpro=259-（Rs- 0.70695）/5.4×10^-5 （Ma）.