scholarly journals Specific heat-temperature curves of some age-hardening alloys

1938 ◽  
Vol 168 (933) ◽  
pp. 237-264 ◽  
Keyword(s):  
Low Temperatures ◽  
Lattice Parameter ◽  
Age Hardening ◽  
Second Stage ◽  
Large Numbers ◽  
Heat Treated ◽  
Or Groups ◽  
Set Up ◽  
Lower Temperature ◽  
Two Stages

In a recent paper Gayler (1937) has dealt with the various theories of age hardening and has put forward the view that ageing takes place in two stages: in the first stage the solute atoms diffuse to planes about which precipitation proper will ultimately take place, and this gives rise to an increase in resistance to deformation and an increase in electrical resistivity without change in lattice parameter. The second stage follows the first and takes place nearly simultaneously. Some of the diffusing atoms will form molecules gradually form groups which will tend to produce a gradual decrease in resistivity and a diminution in the rate of hardening. When the molecular groups have grown to such an extent that the parent solid solution can no longer withstand the stresses set up, release of these stresses is caused by rejection of the groups, i. e. precipitation proper takes place. Once precipitation has set in them, according to Gayler's view, softening should begin. This theory tends to combine the "Knot" theory (Gayler and Preston 1932), which states that age-hardening occurs due to the formation of clusters or groups of atoms inside the parent lattice (the first stage, according to Gayler), and the precipitation theory (Merica and other 1919) which attributed hardening to the presence of large numbers of precipitated particles, probably ultramicroscopic in size, dispersed throughout the material. Naturally the formation of clusters or knots will occur at a lower temperature than precipitation, so that at low temperatures hardening will occur by the mechanism of the first stage. At high temperatures hardening may take place due to precipitation, the first stage being masked entirely. The question as to which of the tow processes is likely to be more effective in any particular alloy when heat-treated to give the maximum hardness obtainable in the hardening range is not specifically dealt with by Gayler, although it is stated that the experimental evidence available suggests that the second stage is, in general, more important. The work of Cohen (1936) on the silver-copper alloy containing 7∙5 % copper supports this contention, since his results show that hardening due to knot formation even at low temperatures (100-150°C) is very small indeed.

Size-Dependent Interdiffusion in Nanomaterials

2005 ◽  
Vol 101-102 ◽  
pp. 123-130 ◽  
Author(s):  
Lyudmila N. Paritskaya ◽  
Yuri S. Kaganovsky ◽  
V.V. Bogdanov
Keyword(s):  
Grain Growth ◽  
Volume Fraction ◽  
Bulk Diffusion ◽  
Solution Concentration ◽  
Lattice Parameter ◽  
Structural Element ◽  
Size Dependent ◽  
Second Stage ◽  
Temperature Homogenization ◽  
Two Stages

The phenomenon of low-temperature homogenization (LTH) during interdiffusion is studied under condition a t Dv £ 2 / 1 ) ( (Dv is the bulk diffusion coefficient, a is the lattice parameter) using nano-objects of binary Cu-Ni and Cr-Ni systems compacted from nano-powders and produced by mechanical alloying. Two stages of LTH were detected: at the first stage (t £ 103 s) the volume fraction of solution rapidly grows; at the second stage (t > 103 s) the volume fraction of solutions grows slowly with practically constant average solution concentration. The first stage of LTH correlates with active grain growth caused by small size (l) of structural element and nonequilibrium structure of nano-objects. Obtained results are analyzed theoretically in terms of interdiffusion along migrating GBs due to grain growth at the first stage and DIGM mechanism at the second stage. It is shown that the GB concentration distribution during interdiffusion along migrating GBs and the kinetics of LTH depend on a parameter l/l where 2 / 1 ) / ( b b V sD d l= is the characteristic diffusion length. The mechanisms and criteria of LTH are proposed.

Cytochemical and ultrastructural differences between intraspecific compatible and incompatible pollinations in Raphanus

1973 ◽  
Vol 183 (1070) ◽  
pp. 21-38 ◽  
Keyword(s):  
Pollen Tube ◽  
The Self ◽  
Self Incompatibility ◽  
Second Stage ◽  
Incompatible Pollen ◽  
Large Numbers ◽  
Third Stage ◽  
Incompatibility System ◽  
Three Stages ◽  
Two Stages

Examination of the behaviour of pollen on the style of Raphanus , following compatible and incompatible intraspecific pollinations, has revealed the self-incompatibility system in this species to be composed of at least three stages. The first, on which no information has been obtained in this study, involves the germination of the grain. The second stage concerns the ability of the pollen tube to penetrate the cuticle of the stigmatic papilla. It is possible that cutinase is deficient in incompatible pollen tubes but, in most instances, the outer layers of the stigmatic wall are penetrated. The third stage involves the interaction of substances secreted by the pollen tube with products of the stigmatic cytoplasm. The interaction is swiftly followed by the deposition, in the stigma, of a layered callosic body. This is formed immediately under the point of penetration and takes about 6 h to develop fully. Development of the pollen tube ceases as the first layers of callose are laid down. It is possible that the substances in the pollen responsible for the initiation of the second two stages are held in the tapetally synthesized tryphine, thus accounting for the sporophytic control of pollen compatibility in this species. The mature stigma contains large numbers of crystalline protein bodies, but it is not known whether they play any role in the self-incompatibility system.

Searching sheet metal parts based on bending process similarity

2003 ◽  
Vol 217 (3) ◽  
pp. 427-438 ◽  
Author(s):  
D Misaki ◽  
S Aomura
Keyword(s):  
Sheet Metal ◽  
Metal Parts ◽  
Sheet Metal Parts ◽  
Second Stage ◽  
Robot Gripper ◽  
Bending Process ◽  
Similar Part ◽  
Set Up ◽  
Two Stages ◽  
Flat Pattern

Sheet metal parts have been widely used in industry and much information for parts has been accumulated in a database. In planning the manufacturing process of a sheet metal part, if the process plan of a similar part can be retrieved from the database, the process planning would be faster and more consistent. In this paper, an effective method of searching the sheet metal parts based on bending process similarity is proposed. This method consists of two stages. In the first stage, flat pattern drawings of the parts with the same set-up numbers are classified into several topological structures. In the second stage, the parts that possess a similar bending process to the target part are selected. The bending process similarity is defined by the grasping position of a robot gripper. The number of reposition and grasping positions are decided by taking the geometric element of the flat pattern into consideration. The effectiveness of this method is described and illustrative examples are shown.

General Practitioners' Knowledge and Use of a Disabled Living Centre

1996 ◽  
Vol 59 (2) ◽  
pp. 79-83
Author(s):  
Anna V Phillips
Keyword(s):  
Monitoring System ◽  
General Practitioners ◽  
Telephone Interview ◽  
Response Rate ◽  
Postal Questionnaire ◽  
Professional Group ◽  
Second Stage ◽  
Set Up ◽  
Two Stages ◽  
To Receive

In March 1994, 141 Aberdeen general practitioners (GPs) were surveyed to clarify why Hillylands Disabled Living Centre (DLC) appeared to receive few direct referrals from this professional group. This was carried out in two stages. The first consisted of a postal questionnaire which received a 77% response rate. This identified that 90% of the 108 respondents knew of Hillylands' existence but only 24% were fully aware of the services it offered. Forty-six per cent had advised someone to visit Hillylands DLC, although only 17% of GPs had visited the centre themselves. The second stage, a telephone interview of 46 volunteer GPs, indicated that some GPs recognised a need to increase their awareness. Some felt that it was not appropriate that they visit Hillylands DLC, although those who had done so had found their visit useful. Recommendations are made to extend the mailing list at Hillylands and to set up a monitoring system to ensure regular liaison and supply of publicity material. It is also suggested that the feasibility of developing a comprehensive publicity initiative be investigated.

scholarly journals A Analysis on Queuing System with Setup Time in Revamp Process

2019 ◽  
Vol 9 (1S4) ◽  
pp. 967-969
Keyword(s):  
Performance Measures ◽  
Generating Functions ◽  
Setup Time ◽  
Repair Process ◽  
The Other ◽  
Queuing Model ◽  
Second Stage ◽  
Time Stage ◽  
Set Up ◽  
Two Stages

In this paper, we study about a M/G/1 Queuing model with single stage of service. Service interrupts during the time of service. The server does not get into the repair process immediately. It gets into a Set up time stage for the prior work to be done. On completion of set up stage service, the server will get into the repair process consisting of two stages, in which first stage is compulsory and the second stage of service is optional. For the model defined, we get the steady state results in closed form in terms of the probability generating functions and all the other execution performance measures of the model defined.

scholarly journals Policies for Improving PM2.5 Particles and GHGs Emissions in a Maritime Port of Taiwan: Evidence Based on the INDC and GGRMA Regulations

2021 ◽  
Vol 9 (12) ◽  
pp. 1315
Author(s):  
Ching-Chih Chang ◽  
Yi-An Tsai
Keyword(s):  
Pollution Reduction ◽  
Evidence Based ◽  
Second Stage ◽  
Reduce Emissions ◽  
Set Up ◽  
Liquid Natural Gas ◽  
Two Stages ◽  
The Impact ◽  
Policy Proposals ◽  
Port Of Kaohsiung

The impact of possible emission reduction policies designed to reduce port emissions in the Port of Kaohsiung in Taiwan was analyzed, focusing on ways to reduce air pollution from CO2, CH4, N2O, PM10, PM2.5, NOx, and SOx generated by vessels, cranes, and truck tractors in the port. This paper was set up in two stages to determine how pollution reduction policies could reach the 2030 and in 2050 goals. The results showed that emissions of CO2, CH4, N2O, PM10, PM2.5, NOx, and SOx could be reduced by 46%, 26%, 25%, 77%, 77%, 76%, and 68%, respectively, in the first stage (in 2030, INDC), and by 57%, 59%, 53%, 79%, 79%, 80%, and 69%, respectively, in the second stage (in 2050, GGGRMA), as compared to 2005 data. This paper concludes as follows: (1) for vessels, the use of liquid natural gas is the best way to reduce GHGs when navigating by water; (2) for bridge cranes, electrification is the better policy during operation; (3) in the case of truck tractors, the generation of battery-electric power is the best way to reduce emissions. These policy proposals for improving air quality can be applied to all ports in Taiwan.

Chlorophyll degradation in heat-treated Chlorella pyrenoidosa. A flow cytometric study

2001 ◽  
Vol 28 (1) ◽  
pp. 79
Author(s):  
Shainnfer Tzeng ◽  
Ban-Dar Hsu
Keyword(s):  
Present Model ◽  
Chlorella Pyrenoidosa ◽  
Chlorophyll Degradation ◽  
Continuous Illumination ◽  
Second Stage ◽  
Flow Cytometric ◽  
Heat Treated ◽  
Pre Treatment ◽  
Set Up ◽  
Flow Cytometric Study

The process of chlorophyll degradation of Chlorella pyrenoidosa was studied by flow cytometry using intrinsic chlorophyll fluorescence as the gauge. The small vegetative cells of a synchronous culture were subjected to a heat pre-treatment (46.5ºC for 1 h in the dark) and cultured again under continuous illumination thereafter. The cellular chlorophylls vanished within about 24 h after the heat pre-treatment in two distinguishable stages, which corresponded to the two major stages of the present model for chlorophyll degradation. It was found that, although both stages were light-dependent, they differed in several aspects. The first stage of degradation, in which the whole cell population uniformly converted its chlorophylls into pheopigments, started immediately after light-on during recultivation, and continued even after light-off for a long period (~60 h), indicating that all cells responded to light without delay, and the process continued once triggered. The second stage of degradation, in which cells opened their chlorophyll macrocycles and lost their green color, did not start until after about 8 h of illumination, and each individual cell actually entered this process at a somewhat different time (8–24 h). In addition, the conversion of each cell was fast, but the process in the population as a whole stopped whenever illumination was off. This indicates that the second stage proceeds in a random mode, and that light must be present during the conversion of each cell. It was also found that the process of pigment breakdown could be turned on by illumination as low as 4 mol m –2 s –1 , but was abolished by a period of dark treatment, suggesting that light played a triggering role, and the ‘signal’ for chlorophyll degradation set up by the heat pre-treatment was automatically canceled after a certain time without light triggering.

scholarly journals Investigation of Karst Spring Flow Cessation Using Grey System Model

2019 ◽  
Author(s):  
Yaru Guo ◽  
Tian-Chyi Jim Yeh ◽  
Yonghong Hao
Keyword(s):  
Anthropogenic Activities ◽  
Climate Variation ◽  
Grey System ◽  
Large Area ◽  
Karst Springs ◽  
Second Stage ◽  
Spring Flow ◽  
Set Up ◽  
One Year ◽  
Two Stages

Globally karst aquifers store large amount of precious water and create beautiful karst springs in many places. However, most of the karst springs flow declined, and some of the karst springs dried up with the effects of extensive groundwater development and climate variation. For example, Jinci Springs (China) is known for the beautiful landscape it created and large area of paddy fields it irrigated. Unfortunately, it dried up in May 1994. For better understanding of the hydrological processes of karst springs, this study introduced grey system models to quantify spring flow taking Jinci Springs as an example. Based on the characteristics of Jinci Springs flow, the spring flow was divided into two stages: the first stage (1954-1960), when the spring flow was affected only by climate variation; and the second stage (1961-1994), when the flow was impacted by both climate variation and anthropogenic activities. Results showed that the Jinci Springs flow had strong relations with precipitation occurring one year and three years earlier in the first stage. Subsequently, a grey system GM (1, 3) model with one-year and three-year lags was set up for the first stage. By using the GM (1, 3) model, we simulated the spring flow in the second stage under effects of climate variation only. Subtracting the observed spring flow from the simulated flow, we obtained the contribution of anthropogenic activities to Jinci Springs cessation. The contribution of anthropogenic activities and climate variation to Jinci Springs cessation was 1.46m3/s and 0.62m3/s, respectively. Finally, each human activity causing spring flow decline was estimated.

scholarly journals Characterization approach to develop distillation process for production of anode-grade coal tar pitch

2021 ◽  
Vol 882 (1) ◽  
pp. 012035
Author(s):  
Phiciato ◽  
S Rianda ◽  
C Irawan ◽  
D Sinaga
Keyword(s):  
Atmospheric Pressure ◽  
Coal Tar ◽  
Operating Conditions ◽  
Vacuum Pressure ◽  
Distillation Process ◽  
Soaking Time ◽  
Second Stage ◽  
Heat Treated ◽  
Distillation System ◽  
Two Stages

Abstract Many efforts have been spent to make a trade-off between designing an efficient distillation system and meeting very strict requirements of pitch product. The design of coal tar distillation for pitch production should be able not only energetically efficient but also to meet the physicochemical requirements of pitch. This paper presents a practical approach and a systematic method of material characterizations to evaluate appropriate distillation operating conditions. The purpose of this study was to develop a simple coal tar distillation process that focused on obtaining anode-grade binder having certain specifications. The distillation process was carried out in two stages. The first stage occurred up to 360-370°C at atmospheric pressure to separate all volatile fractions. The second stage distillation involves vacuum pressure with 4 conditions in which A<B<C<D ranging from -4 to -35 cmHg and varying soaking time to convert soft pitch into hard pitch. Higher vacuum pressure of distillation is not necessarily high to meet specifications. Our finding shows that B is the most favourable vacuum pressure and can be further heat treated for specific requirements of pitch.

scholarly journals Investigation of Karst Spring Flow Cessation Using Grey System Models

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1927
Author(s):  
Yaru Guo ◽  
Tian-Chyi Jim Yeh ◽  
Yonghong Hao
Keyword(s):  
Anthropogenic Activities ◽  
Strong Relationship ◽  
Climate Variation ◽  
Grey System ◽  
System Models ◽  
Second Stage ◽  
Spring Flow ◽  
Set Up ◽  
One Year ◽  
Two Stages

Karst aquifers are prominent sources of water worldwide; they store large amounts of water and are known for their beautiful springs. However, extensive groundwater development and climate variation has resulted in a decline in the flow of most karst springs; some have even dried up. In order to obtain a better understanding of the factors contributing to this development, this study introduced grey system models, which quantified spring flow, taking Jinci Springs (China), which dried up in May 1994, as an example. Based on the characteristics of Jinci Springs, spring flow was divided into two stages: first (1954–1960), when the spring flow was affected only by climate variation; and second (1961–1994), when the flow was impacted by both climate variation and anthropogenic activities. The results showed that Jinci Springs flow had a strong relationship with precipitation occurring one year and three years earlier in the first stage. Subsequently, a grey system GM (1,3) model with one-year and three-year lags was set up for the first stage. By using the GM (1,3) model, we simulated the spring flow in the second stage under effects of climate variation only. By subtracting the observed spring flow from the simulated flow, we obtained the contribution of anthropogenic activities to Jinci Springs’ cessation. The contribution of anthropogenic activities and climate variation to the decline was 1.46 m3/s and 0.62 m3/s, respectively. Finally, each human activity that caused the decline was estimated. The methods devised herein can be used to describe karst hydrological processes that are under the effects of anthropogenic activities and climate variation.

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