Inter-caste Marriage in Eastern Nepal： Context and Its Consequences

This study explores the current situation of inter-caste marriage in Eastern Nepal. It is based on a sample of 30 inter-caste couples collected in Sunsari District. It basically describes the extent and pattern of inter-caste marriage and responsible factors to be engaged in inter-caste marriage among diverse social groups. Inter-caste marriage is not only a matter of individual relation; it is also a matter of society and social transformation from traditional to modern. Love and affection, age factors, good moral character of the lower caste, modernization, migration, education, mass media, and identity based moments are taken major motivational factors for inter-caste marriage. Inter-caste couples are victimized from various factors of traditional society; they are facing different kinds of problems from their family, relatives, and society. Family problems, social problems, cultural problems, and psychological problems are the common for them.

Extrusion force analysis of aluminum pipe fabricated by CASTEX using expansion combination die

To determine the extrusion force of pipe fabricated by continuous casting and extrusion (CASTEX) using an expansion combination die, the metallic expansion combination die was divided into diversion zone, expansion zone, flow dividing zone, welding chamber, and sizing zone, and the corresponding stress formulae in various zones were established using the slab method. The deformation zones of CASTEX groove were divided into liquid and semisolid zone, solid primary gripping zone, and solid gripping zone, and the formulae of pipe extrusion forces were established. Experiments were carried out on the self-designed CASTEX machine to obtain the aluminum pipe and measure its extrusion force using the expansion combination die. The experimental results of radial extrusion force for aluminum pipe are in good agreement with the calculated ones.

mRNA expression and DNA methylation in three key genes involved in caste differentiation in female honeybees(Apis mellifera)

In honeybee （Apis mellifera） colonies, queens and workers are altemative forms of the adult female honeybee that develop from genetically identical zygotes but that depend on differential nourishment. Queens and workers display distinct morphologies, anatomies and behavior, better known as caste differentiation. Despite some basic insights, the exact mechanism responsible for this phenomenon, especially at the molecular level, remains unclear although some progress has been achieved. In this study, we examined mRNA levels of the TOR （target of rapamycin） and Dnmt3 （DNA methyltransferase 3） genes, closely related to caste differentiation in honeybees. We also investigated mRNA expression of the S6K （similar to RPS6-p70-protein kinase） gene linked closely to organismal growth and development in queen and worker larvae （1-day and 3-day old）. Last, we investigated the methylation status of these three genes in corresponding castes. We found no difference in mRNA expression for the three genes between 1st instar queen and worker larvae; however, 3rd instar queen larvae had a higher level of TOR mRNA than worker larvae. Methylation levels of all three genes were lower in queen larvae than worker larvae but the differences were not statistically significant. These findings provide basic data for broadening our understanding of caste differentiation in female honeybees.

Optimization of flow control devices in a tenstrand billet caster tundish

The physical model of a ten-strand billet caster tundish was established to study the effects of various flow control devices on the melt flow. Before and after the optimization of the melt flow, the inclusion removal in the tundish was evaluated by plant trials. The physical modeling results show that when combined with a baffle, the turbulence inhibitor, instead of the impact pad, can significantly improve the melt flow. A turbulence inhibitor with a longer length of inner cavity and without an extending lip at the top of the sidewall seems to be efficient in the improvement of the melt flow. Various types and designs of baffles all influence the flow characteristics significantly. The "V" type baffles are better than the straight baffles for flow control. The "V" type baffle with four inclined holes at the sidewall away from the stopper rods is better in melt flow control than the one with one inclined hole at each sidewall. The combination of a well-designed turbulence inhibitor and an appropriate baffle shows high efficiency on improving the melt flow and an optimal proposal was presented. Plant trials indicate that, compared with the original tundish configuration in prototype, the inclusions reduce by 42% and the inclusion distribution of individual strands is more similar with the optimal one. The optimal tundish configuration effectively improves the melt flow in the ten-strand billet caster tundish.

On the Symbols of The Mayor of Casterbridge

Thomas Hardy(1840-1928)is a famous British Novelists.His excellent works have a far-reaching significance to the later gen erations.Treating his The Mayor of Casterbridge as a text,this paper is aimed to detect Hardy's implied meanings of the symbols in a through textual analysis.This thesis is divided into three parts.The first part is the the symbol of the bridges.The second part deals with the symbol of the mel ody.Part three explores other symbols in The Mayor of Casterbridge.The symbols are all deliberately chosen in this book by the author to transmit his tragic view.Through the symbols of the bridges,the melody,the church,the tractor,the railway…,the author's tragic view is well presented.By the research of each of those three parts,the conclusion of Hardy's functions of the symbols can be drawn.

On the Tarmac of Nationhood： Dismantling Caste and Tribal Loyalty in Aravind Adiga＇s The White Tiger and Shadrach Ambanasom＇s Son of the Native Soil

The White Tiger is Aravind Adiga＇s first novel just like Son of the Native Soil which is Shadrach Ambanasom＇s first oeuvre. The two novels address two major social concerns （the caste system and tribal loyalty） that impair national cohesion in India and Cameroon respectively. Briefly speaking, the caste refers to the classification of peoples in India （and other South Asian countries） into in-marrying hereditary social classes of the privileged and the underprivileged while tribal loyalty refers to selfish attachment to a tribe or clan to the detriment of community or national feeling. The two concepts are related in the sense that the word ＂caste＂ derives from the Spanish or Portuguese ＂casta＂ meaning race, lineage, breed or clan. In both cases therefore, the issues of sectionalism, division, discrimination, selfishness, marginalization, and hegemony （amongst others） are at play--issues that impede the notion of nationhood. Read principally from the Marxist perspective of power dynamics and class struggle, the paper argues that Adiga and Ambanasom through skillful manipulation of symbols, time, characters and events, try to imagine the deconstruction of caste and ethnic loyalty in India and Cameroon respectively, which to the two authors, are only historically and socially erected edifices rather than natural order. For the two authors, although global forces may seem to play in favor of a more equitable human society, a necessarily violent revolution might be required to dismantle a blighted body politico-modus operandi that has operated in the people＇s psyche for a long time, as characters and events in the two novels reveal.

Numerical Simulation of Linear Electromagnetic Stirring in Secondary Cooling Region of Slab Caster

According to the theory of alternating magnetohydrodynamics and magnetic boundary renewal method,mathematical models were proposed for electromagnetic stirring in secondary cooling region( SEMS) of slab caster. The magnetic fields and flow fields of melt were simulated with SEMS. It's shown that the electromagnetic forces with inward and sidelong components produced by travel magnetic field at the wide faces of slab make the melt whirling in horizontal section,and the convection of the melt is strengthened obviously there. In addition,magnetic flux density attenuates from the edge to the center of slab,and the profile of the melt velocity along slab thickness in the center of the horizontal section takes a two-opposite-peak configuration. Ultimately,the stirring intensity and features are determined by the electromagnetic parameters,coil arrangement and stirring types.

Numerical and physical simulation of a twin-roll strip caster

The 1：1 water model of a twin-roll strip caster was set up based on the Froude number and the Reynolds number similarity criteria. A new type metal delivery system was designed for the twin-roll strip caster. The level fluctuation and the fluid flow in the pool of the water model were measured using the level detector and the 3D-LDV （laser Doppler velocimetry） technology. It is shown that a wedged delivery system can produce the desirable level fluctuation and even fluid flow distribution in the pool Numerical simulations for the water model were performed. Comparisons between the numerical and physical simulation results show good agreement near the side dams.

Surface turbulence in a physical model of a steel thin slab continuous caster

In the thin slab continuous casting （TSCC） of steel, the issue of optimum fluid flow is very important due to higher casting speeds and has direct influence on the formation of solidified shells and the quality of final products. In the current work, a full-scale physical mod- eling of a thin slab easter on the basis of dimensionless Reynolds and Froude similarity criteria was constructed. The flow pattern in the funnel shaped mold with a new tetra-furcated submerged entry nozzle （SEN） was investigated. To determinate optimum operational parameters, some experiments were carried out under various casting conditions. The results show that the tetra-furcated design of the nozzle leads to a special flow pattern in the mold cavity with three-dimensional recirculating flow. It is also shown that the increase of casting speed and gas injection results in surface turbulence. On the other hand, using a higher depth of SEN decreases the vortex in the free surface of the caster. To avoid surface turbulent and related casting problems, it is recommended to use 30-cm and 40-cm SEN depth at the casting speeds of 3.5 and 4.5 m/min, respectively.

SMART/ASTC dynamic soft reduction technology and its application on the bloom continuous caster at Pangang

The SMART/ASTC dynamic soft reduction technology of VAI and its application on the 6-strand bloom continuous caster at Pangang, China are presented. The operation results show that soft reduction technology is effective to improve the inner quality of continuously cast blooms. At Pangang, both the central porosity and the central segregation ratings are no more than 1.0, the central shrinkage cavity rating is no more than 0.5, and the central segregation index of carbon is no more than 1.05. Rails made from the blooms have excellent quality and are used for high-speed tracks.

Study on Level Fluctuation of Twin Roll Strip Caster by Water Modeling

An industrial trial was conducted on a billet casting machine at Atlas Steel, Canada, during which a mould was instrumented with 52 thermocouples. The measured data of ten heats were collected to determine mould wall temperature profiles for different steel grades at different casting speeds. Based on these data, heat fluxes were calculated with inverse heat conduction model. Heat fluxes for different operating parameters were compared and analyzed.

UPPER-BOUND APPROACH ANALYSIS OF DRIVING POWER OF WHEEL FOR CASTEX

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Numerical Simulation of Fluid Flow and Heat Transfer in Funnel Shaped Mold of Thin Slab Continuous Caster

Thin slab casting is used widely in the world. The control of molten steel flow and solidification in the mold is difficult due to the high casting speed and complicated configuration of the mold. Numerical simulation was carried out to study the fluid flow and heat transfer in the funnel shaped mold. The influence of nozzle design, casting speed and nozzle submersion depth on the flow and temperature fields in the mold was investigated, and guidance for selecting configurations of submerged nozzle was obtained.

Microstructure of AISI 304 stainless steel strips produced by a twin-roll caster

By optical inspection of macro-etched metallography and electron back-scattered diffraction （EBSD） mapping, this paper analyzed the microstructure of austenitic stainless steel strips produced with an equal-diameter twin-roll strip caster. The results indicate that the microstructure of the strips includes two columnar zones with highly compact dendrites and one equiaxed zone. The characteristics, such as grain size and growing direction of columnar grains and equiaxed grains, were investigated. An additional transitional area with many finer grains between the columnar zone and the equiaxed zone was found. As shown in EBSD analysis, small angle boundaries exist both in the columnar zone and the equiaxed zone, although they are especially more in the transitional area. Additionally, some 〈111〉 twin boundaries were found in the microstructure of the strips.

Extensive Analysis of Multi Strand Billet Caster Tundish Using Numerical Technique

Continuous casting of steel involving different grades in the same casting sequence remains a challenge to billet caster operators. The intermixed composition obtained during the grade change does not meet the specification of either grade and must be downgraded. Incorrect identification of this intermixed region may result in non-conforming products reaching the customer. In this study, a numerical model based on CFD (computational fluid dynamics approach) has been developed which predicts the start and end of the intermixed composition and the tonnage to be downgraded under different casting conditions. This model was validated and the results were in good agreement with the actual plant data for a 6-strand billet caster at LD-1 of TATA Steel, India. This model is used to calculate transition tonnage for different scenarios, e.g. when one of the outermost strands is not functional or some combinations are not functional and varying casting speed during operation. Furthermore, impact of different design of baffles on performance of Tundish has been evaluated to find a way to reduce transition or intermixed composition.

INFLUENCES OF CASTING SPEED AND SEN DEPTH ON FLUID FLOW IN THE FUNNEL TYPE MOLD OF A THIN SLAB CASTER

In recent years, thin slab continuous casting technology has been widely used to improve the quality of the product and to reduce the cost. One of the challenges faced by this technology is to design reasonable flow patterns, which strongly affect the surface and inner properties of the final slab in the mold. With the fixed scales and complex geometrical structures of nozzle and funnel type mold, a series of numerical simulations are made to analyze the flow patterns in melt steel using finite volume method based on structured body fitted coordinate grids. The CFD （computational fluid dynamics） package is validated first using one typical case described in previously published studies, and then it is developed to study the effect of operational parameters on fluid flow in thin slab caster. Two operational parameters, casting speed and SEN （submerged entry nozzle） depth, are mainly considered for numerical analysis. On the basis of present simulations, the reasonable SEN submergence depths corresponding to different casting speeds are suggested according to fluid flow characteristics like, flow jet impingement on the narrow side of the mold, flow speed of the melt steel beneath the meniscus and the recirculation region. This is the first stage of study on the numerical analysis of the whole thin slab casting process with electromagnetic brake.

Bonding of compound casted Ti/Al bimetal by heat treatment

The formation mechanism of the bonding between compound cast Al/Ti bimetal during a heat treatment regime was investigated.Commercially pure Al was cast and melt on a Ti bar in a steel tube,followed by heat treatment on the compound cast Ti/Al bimetal for different periods of time once the Al melt was solidified.No bonding was observed between the two metals after the initial casting,which can be attributed to the presence of oxide films on the liquid Al and solid Ti alloys and the trapped atmosphere between them.The effect of these layers in preventing the formation of bonding was eliminated after heat treating the cast part at~973 K(~700℃)for at least 15 min,and the metals started to bond with each other.A detailed description of this bonding mechanism is presented in this paper.

Behavior of Liquid Steel in Mold for Thin Slab Caster

The comparison of different submerged entry nozzles(SEN)was made by numerical simulation regarding the influence of liquid steel flow field,heat transfer and mold fluxes,as well as solidification shell stress and surface quality of thin slabs.The optimum internal shape of mold and the SEN were obtained.The foundation for choice of internal shape and casting parameters of mold was built.

Preparation of AZ31 magnesium alloy strips using vertical twin-roll caster

A newly developed technology for manufacturing magnesium alloy strip,vertical twin-roll strip casting,has been described.This manufacturing process is easy to be facilitated in an economical way to manufacture wrought magnesium alloy strips. As an example,AZ31 magnesium alloy was used to investigate the appropriate manufacturing conditions for vertical twin-roll strip casting by varying the temperatures of the molten materials and rolling speeds.The effects of manufacturing conditions on forming quality were clarified in terms of roll speeds and casting temperature.In addition,microscopic observation and X-ray diffraction of the as-cast strips were performed.It has been determined that AZ31 alloy strip of 1-3 mm in thickness can be produced at a speed of 30 m/min by a vertical twin-roll caster.The microstructure of as-cast strip only containsα-phase(Mg)and no other phase,and the twin-roll casting process can effectively refine the grain size.The fine equiaxed grain of as-cast strips is beneficial to the plastic deformation of the strips,and it is also suitable for direct cold-rolling with a maximum cold-rolling reduction of 40%.

Electromagnetic Dam in Twin-Roll Strip Caster

The electromagnetic dam （EMD） in twin-roll strip caster was simulated with FEM. The results show that the direction and magnitude of Lorentz force distributing in the EMD changed in a period. The negative part is about 30% of the positive part, and the acting time of the negative force is about 40% of a period. In order to prevent the liquid steel from leaking efficiently, the distance between two poles should be the same from the top to the bottom of the EMD, otherwise the magnetic induction will be very small at the top and large at the bottom.