Photosynthetic efficiency, cell volume, and elemental stoichiometric ratios in Thalassirosira weissflogii under phosphorus limitation

Nutrient limitation is known to inhibit growth and metabolism and to alter elemental stoichiometric ratios in phytoplankton. In this study, physiological changes in Thalassirosira weissflogii were measured under different dissolved inorganic phosphate (DIP) regimes in semi-continuous cultures to revisit the utility of the Redfield ratio for assessing nutrient limitation. The results showed that cell size increased with decreasing DIP availability. In the P-depleted treatment (f/2-P) the cell size was 1.48 times larger than that in the P-limited (f/100) treatment and 2.67 times larger than that in the P-saturated treatment (f/2 and f/10). The fucoxanthin to chlorophyll a ratio (Fuco/chl a) was relatively stable (about 0.3) in P-saturated cultures and was 10 times higher than that in P-limited and P-depleted cultures. During the experimental period, the photosynthetic efficiency index, ?F/Fm′, was relatively stable at ~0.50 in the P-saturated cultures, but quickly declined with decreasing DIP availability. Although cellular P content showed a significant difference between the P-saturated culture (1.6 pg/cell) and the P-limited culture (0.7 pg/cell), the N/P ratio in T. weissflogii did not show a trend with DIP availability and fluctuated slightly around 25. Our results suggest that cell division in T. weissflogii is not strictly size-gated but is probably regulated by a biochemical, and hence, an elemental stoichiometric ratio threshold, and that deviation of the cellular N/P ratio from the Redfield ratio is not a reliable indicator of algal nutrient stress.

Ratios of Closely Related Elements in Soil and Their Implications

This paper has investigated the ratios of closely related elements such as Mn,Cr,V,Ni,Co,Cu,Pb,Cd,Ba,Sr,La and Ce in the major soils of China,and the factors affecting them,and explored their use as indicators in soil formation,material transport and environmental pollution.Results show that the effect of soil-forming processes on the ratios of closely related elements varied with different elements,and became greater in the sequence of Ce/La <V/Cr≈Ni/Co<Zn/Cu≈Zn/Pb<Zn/Cd<Mn/Cr<Ba/Sr.The magnitude of the variation in the ratios of closely related elements depended on the chemical properties of the elements themselves,on the one hand,and the parent material and climatic conditions on the other.The ratio of Ba/Sr showed a distinct zonality,decreasing gradually in the sequence:cool temperate zone acid soils>grassland soils>desert soils and increasing gradually from the semi-arid subhumid zone soils>the temperate zone neutral soils>the north subtropic zone soils>tropical and subtropical acid soils.

ADAPTIVE EIGENFREQUENCY ANALYSIS BY IMPROVED r-AND h-ADAPTIVE FINITE ELEMENT METHOD BASED ON PERTURBATION AND ELEMENT ENERGY RATIO

A new adaptive technique of r-and h-version for vibration problemsutilizing the matrix per- turbation theory and element energy ratiois proposed. In structural vibration analysis, through the r-conver-gence adaptvie finite element process, mesh optimization can berealized. In the light of the judgement on the changes in themagnitude of the element energy ratio, local refinement can beachieved in the process of h- convergence adaptive finite element sothat more accurate finite element solutions can be obtained with asfew meshes as possible. Many numerical examples are given and theproposed approach is shown to be feasible and effective.

Study on the packed volume and the void ratio of idealized human red blood cells using a ?nite-discrete element method

Numerical simulations are performed to examine the packing behavior of human red blood cells(RBCs). A combined ?nite-discrete element method(FDEM) is utilized, in which the RBCs are modeled as no-friction and no-adhesion solid bodies. The packed volume and the void ratio of a large number of randomly packed RBCs are clari?ed,and the effects of the RBC shape, the mesh size, the cell number, and the container size are investigated. The results show that the packed human RBCs with normal shape have a void ratio of 28.45%, which is slightly higher than that of the ?at or thick cells used in this study. Such information is bene?cial to the further understanding on the geometric features of human RBCs and the research on RBC simulations.

Use of Finite Element Analysis for the Prediction of Driver Fatality Ratio Based on Vehicle Intrusion Ratio in Head-On Collisions

To estimate the aggressivity of vehicles in frontal crashes, national highway traffic safety administration (NHTSA) has introduced the driver fatality ratio, DFR, for different vehicle-to-vehicle categories. The DFR proposed by NHTSA is based on the actual crash statistical data, which makes it difficult to evaluate for other vehicle categories newly introduced to the market, as they do not have sufficient crash statistics. A finite element (FE) methodology is proposed in this study based on computational reconstruction of crashes and some objective measures to predict the relative risk of DFR associated with any vehicle-to-vehicle crash. The suggested objective measures include the ratios of maximum intrusion in the passenger compartments of the vehicles in crash, and the transmitted peak deceleration of the vehicles’ center of gravity, which are identified as the main influencing parameters on occupant injury. The suitability of the proposed method is established for a range of bullet light truck and van (LTV) categories against a small target passenger car with published data by NHTSA. A mathematical relation between the objective measures and DFR is then developed. The methodology is then extended to predict the relative risk of DFR for a crossover category vehicle, a light pick-up truck, and a mid-size car in crash against a small size passenger car. It is observed that the ratio of intrusions produces a reasonable estimate for the DFR, and that it can be utilized in predicting the relative risk of fatality ratios in head-on collisions. The FE methodology proposed in this study can be utilized in design process of a vehicle to reduce the aggressivity of the vehicle and to increase the on-road fleet compatibility in order to reduce the occupant injury out- come.

NUMERICAL CONSTRAINTS ON TRACE ELEMENT RATIOS DURING FRACTIONAL CRYSTALLIZATION OF IGNEOUS SYSTEM

The constraints on the variation in the ratios of pairs of trace elements during crystal fractionation are described by using a set of inequality functions. This approach to the interpretation of the variation in trace element ratios provides a more thorough basis for describing the quantitative relationships between the variation of trace element ratios during the fractional crystallization, the difference of the bulk distribution coefficients of the two elements and the degree of fractionation. The constraints imposed by the inequalities lead to certain consequences on the variation in the ratios of pairs of trace elements during crystal fractionation. For these consequences not yet recognized in literature detailed explanation will be given in the present paper.

Finite element analysis on the collapse of infill walls with holes and different length-to-height ratios

Wenchuan earthquake damage survey displayed the major structures of buildings suffered only small damages,but it was common that infill walls suffered heavy damages or even collapse. To study the failure forms and collapse mechanism of infill walls in an earthquake,the influence of opening or length-to-height ratio on shake-resisting capability of filling walls was analyzed,and measures to improve the anti-collapse ability of infill walls were put forwaed. The numerical simulations on collapse process in earthquake were carried out by using ABAQUS software. We used 5 single story and single span models. It is revealed that the rigidity and compressive capacity of infill walls are reduced because of the infill walls with holes and the increases of length-to-height ratios. Adding constructional columns and horizontal beams can ensure structural integrity and improve the anti-collapse ability of the wall.

The spatial temporal evolution characteristics of the load／unload response ratio（LURR） and its implications for predicting the three elements of earthquakes

The spatial temPOral evolution characteristics of the load/unload response ratio (Y) before strong earthquakes is studied in this paper. The results show that the regions of high value of Y migrate and converge to the impending earthquake epicenter from different directions before the occurrence of the event. Basing on this discovery, it is proposed that the method can be used to predict the three elements of an earthquake. It was applied to predict that an earthquake would occur in the western part of Yunnan Province, southwestern China. The three elements (time, space and magnitude) of the Menglian earthquake with Ms7.3 which occurred on July 12, 1995 in Yunnan Province tallied with our prediction.

Chemical characteristics of aerosols at coastal station in Hong Kong.Ⅱ. Environmental behavior of trace elements during the April 1995 to April 1996

An one-year of sampling aerosol program was carried out during the period of April 1995 to April 1996 at coastal region, Cape D′Aguilar, in Hong Kong. The trace element composition of aerosol particles(TSP and PM 10 ) were measured and analyzed by using the Instrumental Neutron Activation Analysis(INAA) and Inductive Couple Plasma-Mass Spectrometry(ICP-MS) techniques. The results showed that the polluted elements such as: V, Zn, As, Pb, Cd, Sb, I, Se, Bi, with high enrichment factor(E.F) values, are derived from anthropogenic sources, while Sc, Al, Fe, Mn, Sm, La, Sr are less than 10 in E.F, these elements are related the crust and soil. The concentration of the trace elements are present seasonal variation i.e. summer low and winter high, whereas the V or noncrustal V(V *) present summer high and winter low, this phenomenon might be explained by local or regional oil combustion sources. Use three type of elemental ratio, e.g. La/Sm, Mn */V * and Bi/Al indicate that both TSP and PM 10 of La/Sm ratios are mainly related to soil and dust, Mn */V * are probably represent fossil combustion and Bi/Al are possibly associated with refuse incineration, ferromanganese alloys and aluminum production. The varimax rotation factor analysis for trace elements was performed. By means of the absolute principal component analysis(APCA) and multiple regression, the contribution of trace elements to possible sources and overall means of trace elements were estimated. The results showed that the present station is impacted by the anthropogenic species, although the quantities are different during the summertime and wintertime.

内凹型负泊松比结构的静载与隔振分析

为进一步实现船舶绿色化和结构轻量化,根据泊松比力学关系式,在内六角型负泊松比结构基础上,在SolidWorks中通过中间内角的倒角操作,建立内凹型负泊松比结构。采用有限元法和压缩实验对泊松比和静载刚度进行分析,采用振动实验对内凹型和内六角结构进行隔振性能对比分析。分析结果表明,相比于内六角结构,内凹型结构的静载刚度提升5.52%,在低于50 Hz的频域中内凹型结构具有更高的加速度振级落差和更低的力传递系数。同时,通过模态分析阐明内凹型结构由于共振而发生的隔振弱化原因。

A‑485‑2合金环形轧制仿真研究

本文选取A‑485‑2合金为研究对象,开展了热压缩实验,热压缩有限元模拟,剖面硬度测试和相比例测试。通过实验,模拟和微观表征测试,分析了热加工历史对材料不同位置相比例和硬度的影响规律,并用于预测A‑485‑2合金材料的力学性能。通过分析可以发现:受到温度的影响,试样芯部残余奥氏体含量大于试样边缘,造成试样芯部的硬度小于试样边缘。基于热压缩所获取的实验数据和环轧机的数据,建立了A‑485‑2合金环轧的有限元模型,开展了环件轧制过程的仿真模拟,并探讨了轧制的成形机制。有限元仿真表明,环件内侧的位移,塑性应变和振荡略小于外侧。

基于有限元法的纺纱胶圈用涤棉混纺骨架线性能研究

为更好地了解纺纱胶圈用骨架线破坏过程,缓解普通胶圈在高速纺纱受力轧断频繁、纺纱质量波动明显的现象,采用有限元法对不同混纺比的涤棉骨架线机械结构进行仿真,运用ABAQUS软件建立涤棉股线的三维模型,模拟骨架线轴向受拉应力分布和变形量变化,验证了仿真模拟的有效性和可行性。在此基础上,进一步优选纺纱胶圈用骨架线的最佳混纺比,并对所纺制股线强伸性、回弹性、蠕变性、热收缩性进行测试。结果表明:T/C 75/2513.1 tex×3股线断裂强力大于1000 cN,断裂伸长率小于15%,强伸性、回弹性、蠕变性和热收缩性符合胶圈骨架线要求,综合性能较为优异。

梁柱线刚度比对方钢管混凝土-钢梁框架抗震性能影响分析

为分析梁柱线刚度比对方钢管混凝土柱-钢梁抗震性能的影响,利用ABAQUS及Python脚本建立了8个相同材料不同梁柱线刚度比的有限元模型,分析了梁柱线刚度比对模型极限承载力、滞回耗能及延性系数的影响。结果表明:钢管混凝土柱-钢梁结构具有良好的耗能能力。随着梁柱线刚度比的提升,该结构的承载能力会有所提高,但当提高到一定程度时,承载能力会下降。建议方钢管混凝土-钢梁框架结构的梁柱线刚度比取值不大于0.355。

Analysis of the geometrical dependence of auxetic behavior in reentrant structures by finite elements

Materials with a negative Poisson＇s ratio（PR）are called auxetics;they are characterized by expansion/contraction when tensioned/compressed.Given this counterintuitive behavior,they present very particular characteristics and mechanical behavior.Geometrical models have been developed to justify and artificiall reproduce such materials＇ auxetic behavior.The focus of this study is the exploration of a reentrant model by analyzing the variation in the PR of reentrant structures as a function of geometrical and base material parameters.It is shown that,even in the presence of protruding ribs,there may not be auxetic behavior,and this depends on the geometry of each reentrant structure.Values determined for these parameters can be helpful as approximate reference data in the design and fabrication of auxetic lattices using reentrant geometries.

A new boundary element solution to evaluate the geometric effects of the canyon site on the displacement response spectrum

This paper presents a step-by-step procedure using the three-dimensional boundary element approach to study the behavior of semi-circular canyons under seismic shear waves. The boundary element code TDASC allows utilization for various canyon geometries, evaluation of concurrent seismic waves and calculation of the ground motions on canyons due to an excitation at any arbitrary point of the incident field. Considering the widening ratio of the canyon(including prismatic, semi-prismatic and non-prismatic canyons), wave characteristics(wavelength, dimensionless period, direction) and maximum amplification pattern, the solution was applied to carry out a series of parametric studies. It was shown that canyon form can significantly affect the displacement amplification, especially at the points located on its edges. By increasing the wave dimensionless frequency(η > 1), the amplification pattern becomes more complex. On the basis of the results from a variety of considered cases, a new expression has been presented for the limiting wavelength beyond which the widening of the canyon will not have a major effect on the displacement amplification. To verify the reliability of the proposed approach, the obtained results, expressed in terms of displacement amplitude, were compared with those from the available published literature and a reasonably good agreement was observed.

Element analysis method of concealed explosive based on TNA

The detection technology of concealed bulk explosives is related to social security and national defense construction and has important research significance. In this paper, an element analysis method of concealed explosives based on thermal neutron analysis is proposed.This method could provide better reconstruction precision for hydrogen, carbon, and nitrogen ratios, making it possible to discriminate explosives from other compounds with the same elements but different proportions, as well as to identify the types of concealed bulk explosives. In this paper, the basic principles and mathematical model of this method are first introduced, and the calculation formula of the element number ratio(the ratio between the nucleus numbers of two different elements) of the concealed explosive is deduced. Second, a numerical simulation platform of this method was established based on the Monte Carlo JMCT code. By calibrating the absorption efficiencies of the explosive device to c rays, the element number ratios of a concealed explosive model under the irradiation of thermal neutrons were reconstructed from the neutron capture prompt c-ray spectrum. The reconstruction values were in good agreement with the actual values,which shows that this method has a high reconstruction precision of the element number ratio for concealed explosives. Lastly, it was demonstrated using the simulation study that this method can discriminate explosives,drugs, and common materials, with the capability of determining the existence of concealed bulk explosives and identifying explosive types.

A note on influence of stress anisotropy on the Poisson's ratio of dry sand

In this study, extender and bender element tests were conducted investigating the small-strain Poisson’s ratio of variable sands, with a focus on the effect of stress anisotropy in order to quantify the sensitivity of Poisson’s ratio to the applied deviatoric stress. Four different uniform sands were tested, including a biogenic sand, a crushed rock and two natural sands, covering a wide range of particle shapes. From these sands, eleven samples were prepared in the laboratory and were tested under variable stress paths,maintaining a constant mean effective pressure while increasing the deviatoric compressive load. Under the application of these given stress paths, the data analysis indicated that the sensitivity of Poisson’s ratio to the stress ratio was more pronounced for sands with irregularly shaped particles in comparison to sands with fairly rounded and spherical grains. For sands with very irregularly shaped particles, the increase of Poisson’s ratio from the isotropic to the anisotropic stress state reached 50%, while this increase for natural sands with fairly rounded particles was in the order of 20%.

Using LA-ICP-MS to analysis elemental composition of statoliths of Scyphozoan jellyfish

Scyphozoan jellyfish outbreak events are drawing increasing attentions during the past decade.Elemental compositions of statoliths are helpful to understand jellyfish life history and blooming mechanisms,but very rare endeavor has been focused on the Scyphozoan class.In this work,we explored the feasibility of element analysis of Aurelia aurita(a representative Scyphozoan jellyfish outbreak species in China)which may be used as proxies of environment parameters during jellyfish living and moving.Statolith crystals of Aurelia aurita were found to be a gathering of hexahedron type trigonal needle with size of 10-50μm long,and 5-10μm in diameter.By using laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS)downhole profiling method,elements such as Ca,Sr,Mg,Na and P were found to be above the limit of detection and limit of quantification.The epidermis of statocyst could significantly impact the element analyses,so the real statolith element signal section needs to be selected based on elements and Ca profiles together with care.By laser ablated a signal spot repeatedly,the analytical uncertainty was about 3%-4%for Sr/Ca content ratio and Mg/Ca content ratio,but above 10%for other element/Ca content ratios(n=3).Based on the analysis of statolith from temperature-control cultured jellyfish,Sr/Ca content ratios among different statoliths of the same jellyfish were about 6%(n=14),demonstrating biological processes/vital effects causing small variations compared with analytical uncertainties.Therefore,Sr/Ca content ratios may be used as a potential proxy to reveal the living environment variations the Scyphozoan jellyfish has experienced,such as temperature history,which is helpful to understand jellyfish bloom mechanisms.

Tao and Golden Ratio: A Scientific View of Contemporary Acupunctural Principles through Geometry

It is universally accepted that the philosophy of the Tao is the essence that animates the Chinese Cosmogony. Therefore, in last decades I have tried to consolidate its scientific background, looking for solid explanations through Exact Sciences (“Between Heaven and Earth” Scientific Basis of the Action of Shao Yin: Lightning’s Physical-Mathematical Analysis”;“Is Traditional Chinese Medicine Definitely an Exact Science?”;“Euclidean Geometry and Traditional Chinese Medicine: Diving into the Real Origin of the Five Elements”;“Solitons: A Cutting-Edge Scientific Proposal Explaining the Mechanisms of Acupuntural Action”) Currently, research on Chinese medicine leads us—with Dr. Erica Arakaki, collaborator and assistant—to verify through a profound bibliographic review the application of Fibonacci’s Golden Ratio in the constitution of T’ai Ji Tu, adding yet more substance to the hypothesis of Acupuncture and demonstrating how said Chinese Ancient Science is not only an empirical knowledge but a wisdom derived from the most ancient exact science: Geometry.

SIMULATION OF THE MAGNETIZATION REVERSAL PROCESS OF RECTANGLE-SHAPED NiFe FILM ELEMENTS UNDER AN ORTHOGONAL MAGNETIC FIELD

The magnetization reversal process of nano-size rectangle-shaped NiFe film elements with different aspect ratios have been investigated under the orthogonally applied magnetic fields by micromagnetic simulation. Different magnetization reversal modes can appear depending on whether the bias field is applied or not. When there is no bias field, double “C” state is the initial reversal state. However, when there is a bias field, “S” state is the starting mode. The larger the aspect ratio is, the larger the switching field is. But, when the aspect ratio is larger than 3, the increase of the switching field ceases. These results can provide useful information to the application of the patterned NiFe film with rectangular elements.