从黑奴制到收成制——美国南方重建时期经济体制和社会阶级结构的变化

美国南方重建时期,农业生产形式从黑奴制走向收成制。收成制的确立,引发商业领域的作物借贷制和乡村商店的兴盛,收成制、作物借贷制和乡村商店共同构成重建时期美国南方新经济体制的基础。随着奴隶制的废除和收成制的确立,奴隶主和奴隶的关系转变为种植园主和佃农的关系。社会阶级结构的其他变化还表现在:第一,种植园主阶级继续占据统治地位,但其权力日益受到商人和企业主的挑战,作为挑战和应战的结果,三者出现相互渗透;第二,自耕农阶级瓦解,部分继续拥有一份薄地,大部分沦为无地的佃农、白人佃农、穷白人和黑人佃农的界限日趋模糊。

10Gb/s EML Module Based on Identical Epitaxial Layer Scheme

A 10Gb/s transmitter module containing an electroabsorption modulator monolithically integrated with a distributed feedback (DFB) semiconductor laser is fabricated using the identical epitaxial layer scheme.Gain-coupling mechanism is employed to improve the single mode yield of the DFB laser,while inductively coupled plasma dry etching technique is utilized to reduce the modulator capacitance.The integrated device exhibits a threshold current as low as 12mA and an extinction ratio over 15dB at -2V bias.The small signal modulation bandwidth is measured to be over 10GHz.The transmission experiment at 10Gb/s indicates a power penalty less than 1dB at a bit-error-rate of 10 -12 after transmission through 35km single mode fiber.

Butt-Joint Monolithically Integrated DFB-LD/EA-MD Light Source for 10Gbit/s Transmission

This paper reports on the design,fabrication,and performance of an integrated electro-absorptive modulated laser based on butt-joint configuration for 10Gbit/s application.This paper mainly aims at two aspects.One is to improve the optical coupling between the laser and modulator;another is to increase the bandwidth of such devices by reducing the capacitance parameter of the modulator.The integrated devices exhibit high static and dynamic characteristics. Typical threshold current is 15mA,with some value as low as 8mA.Output power at 100mA is more than 10mW.The extinction characteristics,modulation bandwidth,and electrical return loss are measured.3dB bandwidth more than 10GHz is monitored.

A Novel Optical Gate by Integration of a Photodiodeand an Electroabsorption Modulator

A compact and stable three-port optical gate has been successfully fabricated by monolithically integrating a simple photodiode and an electroabsorption modulator. The gate shows an excellent DC logic ＂and＂ function with different load resistors. Its dynamical characteristics without packaging have also been measured. We observed a dynamic extinction ratio of over 7dB with a 95012 load resistor and a 7mW control light power at 622Mbit/s.

Cost control based on value chain paying equal attention to earning more income and cutting down expense

According to the idea of cost control based on the value chain, several important factors are necessary. Firstly, it is necessary to have enough resources, which must be invested to create advantageous value chain based on customer value. It is also necessary to be sure of the cost advantage of the value chain. Secondly, the consumption of resources must be reduced as much as possible to enable the smallest operating cost for the value chain and make sure of the cost advantage based on maximum business value or profit. It is a kind of cost control from the whole view of creation and supply of value. In practice, it is also a kind of cost control system based on the value chain. It includes enough control and necessary resource investment from the view of the value creation, and keeps consumption of resources to a reasonable level from the view of the value supply. The main object of the first factor is to construct the advantageous value chain from creating customer value; and the second factor is to strengthen the advantageous value chain from supplying or producing customer value. Therefore it is a new kind of idea to explore this cost control from the whole view of creation and supply of value. It is more profitable for businesses to gain sustainable competitive advantage.

AN IMPROVED GENETIC ALGORITHM FOR SEARCHING OPTIMAL PARAMETERS IN n-DIMENSIONAL SPACE

An improved genetic algorithm for searching optimal parameters in n-dimensional space is presented, which encodes movement direction and distance and searches from coarse to precise. The algorithm can realize global optimization and improve the search efficiency, and can be applied effectively in industrial optimization, data mining and pattern recognition.

Industrial Equipment Troubleshooting with Imaging Technique Improved Gamma-Ray Absorption Scans

Gamma scanning is one of the most common nuclear techniques on troubleshooting industrial equipments like distillation columns and reactors. With a very simple concept, the technique is easy to implement. Searching for a competitive edge the industry has been long developing solutions to achieve better results. On the last decades, significant development has been done with the advent of new equipments, electronics, portable computers and software. Continuous scanning and wireless detection systems are examples of successful field solutions, while new software aid on reporting and data presentation. However the type and quality of the results itself has not dramatically changed since its beginning. A scan profile is simple to understand, although the process to build it can be very complex as it requires a specific blend of knowledge and abilities. Process engineering, chemical engineering, internal hydraulic project, nuclear engineering and field abilities are pre requisites for of any scan specialist. Correct data gathering, interpretation and reporting are abilities often difficult to match or requires a long time of training. The industry faces a similar difficult on the customer side, as it is always necessary to train end users to understand a report and how to use its best. This paper describes our effort on developing a new approach on the gamma scan test using image reconstruction techniques that would result on a graphic image rather than a XY plot. Direct and easier to understand, a report with graphic images would be also be accessible to a wider audience, not limited to the customers experienced with gamma scan interpretation.

High Logistics Cost, Toll Road and Institutional Factors Countermeasure in China

Logistics industry has become the driving force of economic growth. However, the logistics industry develops very slowly because the institutional factors have critically hindered the whole development of logistics industry in China. Institutional factors are regarded as the important factor for logistics cost under the market segmentation of peasant mentality. By comparison of the institutional costs in United States, Japan, India and the Europe, deep reason of high cost behind cost driving force is analyzed. Countermeasure is put forward, such as reducing the prices of domestic toll road, using fuel tax as implemented for highway construction funds, and decreasing the restricted policy for carrying freight cars etc..

Role and Mechanism of Functional Components in Promoters for Enhancing FCC Propylene Yield

Phosphorus （P） and metal （M） components were incorporated into promoters for enhancing FCC propylene yield, and the reactive behavior of promoters, before and after modification, were investigated. The results showed that both LPG and propylene yields were increased, and propylene selectivity was improved after the incorporation of P or M into the matrix, resulting in an increased C3 to C4 ratio in LPG during FCC process. But the sole incorporation of M into the matrix also led to an increase in coke and H2 yields on the other hand. Simultaneous modification of the matrix by P and M components resulted in more enhancement in propylene yield and selectivity along with little influence on FCC product distribution. Physico-chemical characterizations and model compound reactions were used to assist in analyzing the mechanism for improving propylene selectivity. Two types of active centers could strengthen the oligomerization of C4 olefins in LPG and these oligomers could be further cracked into C3 olefins on ZSM-5 zeolite, therefore maximizing the ratio of C3 to C4 in liquefied petroleum gas obtained during FCC process.

Fabrication of cost effective iron ore slime ceramic membrane for the recovery of organic solvent used in coke production

Improvement of coking properties of sub-bituminous coal （A） and bituminous coal （B） was done using blended organic solvents, namely, n-methyl-2-pyrrolidinone （NMP） and ethylenediamine （EDA）. Various solvent blends were employed for the coal extraction under the total reflux condition. A low-cost ceramic membrane was fabricated using industrial waste iron ore slime of M/s TATA steel R＆D, Jamshedpur （India） to separate out the dissolved coking fraction from the solvent-coal mixture. Membrane separations were carried out in a batch cell, and around 75 % recovered NMP was reused. The fractionated coal properties were determined using proximate and ultimate analyses. In the case of bituminous coal, the ash and sulfur contents were decreased by 99.3 % and 79.2 %, respectively, whereas, the carbon content was increased by 23.9 % in the separated coal fraction. Three different cleaning agents, namely deionized water, sodium dodecyl sulphate and NMP were used to regain the original membrane permeability for the reusing.

Study on falling film generation heat transfer of lithium bromide solution in vertical tubes

Falling film generation process in lithium bromide absorption refrigeration generation system is researched in thispaper. To describe the coupled heat and mass transfer of laminar falling film in vertical generation tube, a mathematicalmodel is developed, in which the effect of mass transfer on heat transfer is carefully evaluated. Moreover,an equation related Re number with solution volume flow was also obtained in given conditions. We carried outthe experiments with the mass fraction of the inlet solution LiBr being 49.5% and obtained an empirical correlationof heat transfer with the film Re number and heat flux in different volume flow. Specifically, when 5kW/m2<qw<25kW/m2 and Re<500 the heat transfer correlation is given as: h=14009.87qw0.0764Re-0.5391.

Controlled synthesis and shape-dependent electromagnetic wave absorption characteristics of porous Fe_3O_4 sub-micro particles

Porous Fe3O4 sub-micro particles with sphere-like, cube-like and walnut-like morphologies were obtained by a two-step process, and the electromagnetic properties of the Fe3O4 particle/wax composites were investigated. The reflect loss was less than -20 dB for all of the composites in different frequency ranges. The cube-like and walnut-like Fe3O4 composites exhibit improved complex permittivity and permeability and dual-frequency and wide bandwidth absorption characteristics, which is mainly attributed to the larger shape anisotropy. Such a high absorption property indicates that these porous Fe3O4 particles with various morphologies are very promising for electromagnetic wave absorptive materials.