scholarly journals Brass products in the coronet excavated from a M2-numbered Sui-Tang-dynasty tomb situated in Kun Lun Company in Xi'an, Shaanxi

2021 ◽  
Author(s):  
Yanbing Shao ◽  
Fengrui Jiang ◽  
Jingnan Du ◽  
Junchang Yang ◽  
Quanmin Zhang
Keyword(s):  
Tang Dynasty ◽  
Hot Forging ◽  
Metallographic Analysis ◽  
Historical Period ◽  
Central Plains ◽  
Second Stage ◽  
Feudal Society ◽  
Composition Segregation ◽  
Tangible Evidence ◽  
Selection Of

Abstract In this study, the brass wires in the coronet excavated from M2 tomb in Xi'an, Shaanxi, dating back to Sui-Tang-dynasty were probed via portable X-ray fluorescence spectrometry (XRF) and scanning electron microscopy in combination with energy dispersive spectrometry (SEM-EDS) techniques. The wires were found to be composed of 83 wt% of copper, 12 wt% of zinc, and 3 wt% of tin. According to the metallographic analysis, the wires were formed by integral hot forging, and were then installed on the coronet after surface cold shaping, via cutting and hammering during the production of the support parts. It indicated that the composition of brass was evenly distributed without obvious composition segregation, revealing the features of the second stage of brass smelting in ancient China, which may prove brass had appeared and brass smelting technology had been mastered in the Sui-Tang-dynasty in the Central Plains of China. In addition, the use of brass in the coronet was in accorded with the hierarchical symbol given to the material by the feudal society. And the selection of brass was based on the dual combination of the excellent mechanical properties and the golden surface of brass. Thus, brass in the Sui-Tang-dynasty historical period was the tangible evidence of the development level of metallurgical technology, and also reflected the artistic and social attributes given to materials by different stages of social development.

scholarly journals Brass products in the coronet excavated from an M2-numbered Sui-Tang-dynasty tomb situated in Kun Lun Company in Xi'an, Shaanxi

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Yanbing Shao ◽  
Fengrui Jiang ◽  
Jingnan Du ◽  
Junchang Yang ◽  
Quanmin Zhang
Keyword(s):  
Tang Dynasty ◽  
Hot Forging ◽  
Metallographic Analysis ◽  
Historical Period ◽  
Composition And Structure ◽  
The Social ◽  
Zinc Smelting ◽  
Properties Of Materials ◽  
Copper Ores

AbstractAncient Chinese brass smelting technology has promoted the invention of zinc smelting, thus becoming an important part of the metallurgical history. However, the information concerning its origin and development is still controversial. In that regard, thorough analysis of composition and structure of the early brass is crucial for studying various stages of the ancient brass smelting technology history. This study aimed to investigate brass artifacts from Kunlun M2 tomb in Xi'an, Shaanxi, dating back during Sui to early Tang Dynasty (581–712 AD). The composition and metallographic characterization of the materials was performed using XRF, SEM–EDS and metallographic analysis. According to the results, brass was composed of 83 wt% of copper, 12 wt% of zinc, and 3 wt% of tin. Furthermore, its microstructure consisted of α-isometric single crystals with some slip lines and a few twinned grains. This indicated that brass was obtained by melting an appropriate mixture of zinc ores and copper ores at a temperature above 920 °C. Furthermore, brass support components were installed on the coronet after integral hot forging and partial cold shaping. Besides, the use of brass in the coronet was in conformity with the social hierarchy of that historical period, and also reflected the attention paid to the properties of materials.

Researching American Muslims: A Case Study of Surveillance and Racialized State Control

2021 ◽  
pp. 1-16
Author(s):  
Hajer Al-Faham
Keyword(s):  
United States ◽  
Science Research ◽  
The United States ◽  
State Control ◽  
Limited Data ◽  
American Muslims ◽  
State Repression ◽  
Second Stage ◽  
Selection Of

How does surveillance shape political science research in the United States? In comparative and international politics, there is a rich literature concerning the conduct of research amid conditions of conflict and state repression. As this literature locates “the field” in distant contexts “over there,” the United States continues to be saturated with various forms of state control. What this portends for American politics research has thus far been examined by a limited selection of scholars. Expanding on their insights, I situate “the field” in the United States and examine surveillance of American Muslims, an understudied case of racialized state control. Drawing on qualitative data from a case study of sixty-nine interviews with Arab and Black American Muslims, I argue that surveillance operated as a two-stage political mechanism that mapped onto research methodologically and substantively. In the first stage, surveillance reconfigured the researcher-researchee dynamic, hindered recruitment and access, and limited data-collection. In the second stage, surveillance colored the self-perceptions, political attitudes, and civic engagement of respondents, thereby indicating a political socialization unfolding among Muslims. The implications of this study suggest that researchers can mitigate against some, but not all, of the challenges presented by surveillance and concomitant forms of state control.

scholarly journals Relationship between climate change and wars between nomadic and farming groups from the Western Han Dynasty to the Tang Dynasty period

2015 ◽  
Vol 11 (4) ◽  
pp. 3567-3595
Author(s):  
Y. Su ◽  
L. Liu ◽  
X. Q. Fang ◽  
Y. N. Ma
Keyword(s):  
Climate Change ◽  
Tang Dynasty ◽  
Animal Husbandry ◽  
Solid Material ◽  
Han Dynasty ◽  
The South ◽  
Central Plains ◽  
Western Han Dynasty ◽  
The Tang Dynasty ◽  
Background Climate

Abstract. In ancient China, the change in regional agriculture and animal husbandry productivity caused by climate change led to either wars or peaceful relations between nomadic and farming groups. From the Western Han Dynasty to the Tang Dynasty there were 367 wars between the two groups. The nomadic people initiated 69 % of the wars, but 62.4 % were won by the farmers. On a 30 year-period timescale, warm climates corresponded to a high incidence of wars. The conflicts between the nomadic and farming groups took place in some areas which are sensitive to climate change. During the cold periods, the battlefields were mostly in the southern regions. The main causes which leading to the above results are following: (1) warm climate provided a solid material foundation for nomadic and farming groups, especially contributed to improve the productivity of nomadic group; meanwhile, the excessive desire for essential means of subsistence in nomadic group could led to wars. (2) During the cold periods, people of farming group moved to the south and construct the south, meanwhile, nomadic group occupied the central plains, thus the battlefields also changed. As the background, climate change plays an indirect role in wars between groups.

scholarly journals Coverage of the Sprayed Objects in the Aspect of the Coefficient of the Spray Surfaces

2018 ◽  
Vol 66 (1) ◽  
pp. 9-16
Author(s):  
Beata Cieniawska ◽  
Deta Łuczycka ◽  
Jan Červinka ◽  
Katarzyna Dereń
Keyword(s):  
Significant Influence ◽  
Strong Relationship ◽  
Morphological Features ◽  
Spray Characteristics ◽  
Mutual Relation ◽  
Second Stage ◽  
Laboratory Conditions ◽  
Two Stages ◽  
Selection Of

The aim of the study was to compare the degree of coverage of the sprayed objects with the selected nozzles in the aspect of the characteristics of the sprayed object, determined by the coefficient of the position of the sprayed surfaces. Studies were conducted in two stages, in laboratory conditions, in which the first step was to determine the characteristics of the sprayed objects, and in the second there were conducted the studies of the degree of coverage. Based on the analysis of the obtained results from the first stage it was stated that the studied plants were characterised by great differentiation of morphological features having a significant influence on the parameters of their spray characteristics. Important was the fact that the use of the coefficient of the spray surfaces Wpo, determining the mutual relation of particular sprayed surfaces facilitates the selection of the most appropriate nozzles and treatment parameters in relation with the morphological features of the plant. In the second stage, concerning the studies of the degree of the coverage it was stated that the selected nozzles differed strongly in the degree of coverage of vertical and horizontal objects. Differentiated coverage for particular nozzles had a strong relationship with the coefficient of spray surfaces, except that the dual‑spray nozzles covered the vertical surfaces better compared to the single‑spray nozzles, which covered the horizontal surfaces better.

Prevention of Historically Challenging Sustained Casing Pressure from Shallow Gas Through Re-Engineered Cement Design and Execution Methodology

2021 ◽  
Author(s):  
Farah Shakina Ezani ◽  
Myat Thuzar ◽  
Avinash Kishore Kumar ◽  
Chee Hen Lau
Keyword(s):  
Mitigation Measures ◽  
Design Parameters ◽  
Two Stage ◽  
Shallow Gas ◽  
Second Stage ◽  
The Past ◽  
Sustained Casing Pressure ◽  
Dual Stage ◽  
Casing Pressure ◽  
Selection Of

Abstract Sustained casing pressure (SCP) is a very costly event for any operator either at production phase or at the end of a well’s lifecycle. SCP is a result of incomplete hydraulic isolation across hydrocarbon bearing zone. In one of the gas fields in Malaysia, notoriously known for shallow gas hazard, drilled development wells which have reportedly been suffering SCP. In the past, various improvements in cement slurry design and placement methods were deployed in order to provide complete zonal isolation, especially at the shallow gas sand, yet SCP issue was encountered occasionally. In the current development campaign, different strategy to providing annulus sealing was adopted. This paper discusses proactive steps taken in the slurry design, fit together with the dual stage cementing approach, as a primary means of placing cement above the shallow hazard interval. During the design phase, essential key parameters that would lead to successful placement of cement in the annulus as well as unique slurry design that suits for two stage cementing methods were studied. Risk involved in first stage cementing is one of the most important steps that should be analyzed in detail and put mitigation measures in place to ensure the second stage cement job can be performed as planned. In addition to the slurry properties, such as fluid-loss value, gas-tightness, etc., thickening time and top of cement (TOC) of the lead slurry in the first stage cement job has become enormously critical in designing dual stage cementing job in order to assure cement ports in the stage collar are not covered with hard cement forcing the termination of second stage job prematurely. Besides cementing design, careful selection of the stage collar location and casing annulus packer in the string is also of significant importance in leading to successful two stage cement job. Two development wells with above approached has been delivered and no sustained casing pressure has been experienced. This proactive approach to use two stage cementing as primary plan has proven to successfully eliminate the risk of SCP, which was a frequent struggle in their sister wells drilled with primary cementing in the past in the same field. The risk analysis combined with careful considerations of critical cementing design parameters and selection of stage tool location have become a novel approach to combat against SCP in this gas field.

scholarly journals Endovascular Treatment of Aneurysms Arising from the Basilar Artery Trunk and Branches

2010 ◽  
Vol 16 (4) ◽  
pp. 369-383 ◽  
Author(s):  
J.-L. Yu ◽  
H.-L. Wang ◽  
N. Xu ◽  
K. Xu ◽  
B. Wang ◽  
...  
Keyword(s):  
Endovascular Treatment ◽  
Basilar Artery ◽  
Aneurysm Rupture ◽  
Parent Artery ◽  
Proper Selection ◽  
Treatment Regimens ◽  
Second Stage ◽  
Endovascular Coil Embolization ◽  
Selection Of

This study reports our experience with the endovascular treatment of basilar artery (BA) trunk and branch aneurysms. Subjects included 16 patients with BA trunk and branch aneurysms who underwent endovascular treatment in our hospital from October 2000 to October 2009, including four patients with associated arteriovenous malformation (AVM), two with associated moyamoya disease, one with multiple aneurysms at adjacent sites, and one with a distant aneurysm. Endovascular coil embolization, together with stent or balloon assistance when necessary, or while occluding the parent artery was performed. Associated diseases were managed intraoperatively or in the second stage, or treated with gamma knife radiotherapy, or followed up. Two patients with unsuccessful embolization died of re-rupture at the fourth month and fifth month follow-up. The remaining 14 patients reported good outcomes and experienced no re-rupture of either the aneurysm or associated disease. Angiographic follow-ups were conducted for the 14 patients for six to 12 months. Digital subtraction angiography (DSA) examination at the last follow-up showed no recurrence of the BA trunk and branch aneurysms. Together, BA trunk and branch aneurysms should be actively managed via endovascular techniques to prevent serious consequences due to aneurysm rupture and bleeding. Favorable outcomes can be obtained by the proper selection of endovascular treatment regimens.

The effect of low sludge age on wastewater fractionation (SS, SI)

2003 ◽  
Vol 47 (11) ◽  
pp. 203-209 ◽  
Author(s):  
S. Haider ◽  
K. Svardal ◽  
P.A. Vanrolleghem ◽  
H. Kroiss
Keyword(s):  
Activated Sludge ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
The Other ◽  
Second Stage ◽  
Lower Maximum ◽  
The Difference ◽  
Selection Of ◽  
Activated Sludge Systems ◽  
Raw Wastewater

In lab-scale experiments at the 2-stage activated sludge pilot plant of Vienna's central WWTP it is shown that the wastewater soluble COD concentration, which is inert to a sludge with SRT < 1 d (SIA) is about double compared to the SI concentration in sludge with SRT > 10 d (SIB). Unexpectedly the ratio of SIA/SIB is independent of the sludge age between SRTs of 0.4 and 1.0 days. The difference between the two SI fractions is soluble COD that is readily biodegradable by the sludge with SRT > 10 d. However, it is degraded at a lower maximum growth rate. These results comply with earlier results gained with different methods and at different WWTPs. It is hypothesised that very low sludge ages result in a selection of fast growing bacteria, which can utilise only part of the SS in the raw wastewater. The other part of SS therefore remains in the wastewater and can thus be utilised for enhanced denitrification in the second stage. It is still unknown beyond which sludge age the soluble inert COD SIA starts to decrease, finally reaching the value SIB for low loaded systems (SRT > 5 days). From this point on SI and SS are assumed only to depend on the wastewater composition and not on the sludge age. The assumption of the Activated Sludge Model No.1 that the biodegradable fractions can be modelled as a single substrate and by a single removal kinetic (one Monod term) appears not to be applicable for low sludge ages. Some suggestions for mathematical modelling, design and operation of 2-stage activated sludge systems are given.

scholarly journals Quantification of the damage caused by Meloidogyne enterolobii in okra

2019 ◽  
Vol 54 ◽  
Author(s):  
Edgard Henrique Costa Silva ◽  
Renato Silva Soares ◽  
Heloísa Oliveira Borges ◽  
Carolina Andrade Franco ◽  
Leila Trevisan Braz ◽  
...  
Keyword(s):  
Agronomic Traits ◽  
Abelmoschus Esculentus ◽  
Second Stage ◽  
Randomized Design ◽  
Meloidogyne Enterolobii ◽  
Completely Randomized Design ◽  
Suitable Measure ◽  
Reproduction Factor ◽  
Selection Of

Abstract: The objective of this work was to estimate the damage caused by Meloidogyne enterolobii in okra (Abelmoschus esculentus) and to verify the reliability of the reproduction factor as a suitable measure for selecting resistant okra genotypes. Increasing populations of M. enterolobii - 0, 500, 1,500, 3,000, 5,000, and 7,000 eggs and second-stage juveniles (J2) per plant, - were evaluated, in a completely randomized design. The pathogen showed a parasitism pattern similar to that of M. incognita, causing a significant decrease in morphological and agronomic traits. The pathogen reproduction factor should be used in the selection of okra genotypes for tolerance to M. enterolobii, in populations above 3,000 eggs or J2.

Integrated Model for MCDM: Selection Contractor in Malaysian Construction Industry

2014 ◽  
Vol 548-549 ◽  
pp. 1587-1595
Author(s):  
Waled Alzober ◽  
Abdul Razak Yaakub
Keyword(s):  
Decision Making ◽  
Construction Industry ◽  
Construction Projects ◽  
Integrated Model ◽  
Decision Making Process ◽  
Contractor Selection ◽  
Second Stage ◽  
Proposed Model ◽  
Two Stages ◽  
Selection Of

A complex or unstructured problem is based on multi criteria not on a single criterion. A contractor selection problem is a multi-criteria problem. A correct decision-making is required for selecting the appropriate contractor for a construction project. Selection of a contractor is a key decision made by clients and the process of selection a contractor has become an important issue in construction projects. Many multi-criteria techniques have been proposed and applied to such problems solution. This paper aims to propose integrated model for MCDM. The integrated model contains two stages. First stage integrates two MCDM methods are AHP and ANN to prepare a shortlist of the best alternatives. Second stage apply statistical model COP to choose the optimum alternative from the best alternatives in a shortlist. Proposed model for tendering system provides automated a decision-making process that reduces the time and manpower requirements for processing tender

Oxidation Behavior of As-Forged Fe-25wt%Cr Alloys at 1100°C in Air

2011 ◽  
Vol 695 ◽  
pp. 348-352 ◽  
Author(s):  
Hui Xie ◽  
Lei Jia ◽  
Xiao Feng Zhang ◽  
Zhen Lin Lu
Keyword(s):  
Oxidation Behavior ◽  
Oxidation Process ◽  
Hot Forging ◽  
Oxygen Ions ◽  
Second Stage ◽  
Parabolic Law ◽  
Transport Velocity ◽  
Fast Transport ◽  
Kinetics Of ◽  
Oxidation Scale

Fe-25wt%Cr alloys were fabricated by combining Powder Metallurgy (PM) with hot-forging treatment, and their oxidation behavior at 1100°C in air was investigated systematically by using XRD, SEM and EDS, respectively. The results showed that a composite oxidation scale containing both Cr2O3and FeCr2O4formed on the surface of as-forged Fe-25wt%Cr alloys after oxidation at 1100°C in air for 100 hours. The oxidation process of Fe-Cr alloys could be obviously divided into two different stages, and the kinetics of two-stage oxidation agreed well with the parabolic law. The first could be corresponding to the formation of protective Cr2O3layer, while the second could be thought as the growth of FeCr2O4and the further oxidation of the inner Cr2O3oxidation scale. The faster oxidation rate in the second stage could be attributed to both the diffusion of iron ions rapider than that of Cr in the Cr2O3layer and the fast transport velocity of oxygen ions along the cracks.

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