Wyniki wyszukiwania - BazTech

1

The relationship between green supply chain performance, energy demand, economic growth and environmental sustainability: an empirical evidence from developed countries

Yu Z., Golpîra H., Khan S. A. R.

LogForum

|

2018

|

Vol. 14, no. 4

479--494

EN

Background: This study is for examining the association between green logistics, energy demand, renewable energy consumptions, environmental performance and sustainable economic development in a panel of nineteen developed economies around the globe over the period from 2008-2017. In addition, the article expands domain of green logistics from firm level to country level and also connects national scale economic indicators with green logistical performance. Methods: The study employs Pools OLS (ordinary least square) statistical technique to check hypothesis, while secondary data have been used, which were downloaded from the World Bank. Results: The results reveal that the green logistics indicators have strongly positive correlation with green energy sources, FDI inflows, and Trade openness. On the other hand, greenhouse gas emissions and carbon emissions have negative correlation with green logistics. Furthermore, renewable energy is a driving factor of green logistics and supply chain operations which also promote environmental and economic sustainability. Conclusion: This article provides the insight of the association between green logistics performance and national scale economic and environmental indicators. In addition, this research will help practitioners, senior managers and policymaker to understand the importance of renewable energy and green practices in logistical operations.

PL

Wstęp: Praca prezentuje wyniki analizy powiązań pomiędzy zieloną logistyką, popytem na energię, konsumpcją energii odnawialnej, wpływem na środowisko oraz zrównoważonym rozwojem ekonomicznych na podstawie 19 rozwiniętych krajów z całego świata w okresie 2008-2017. Dodatkowo, omówiono rozwiniecie zielonej logistyki z poziomu przedsiębiorstwa do poziomu kraju jak również powiązano krajowe ekonomiczne wskaźniki z działalnością zielonej logistyki. Metody: Zastosowano metodę statystyczną Pools OLS dla sprawdzenia postawionych hipotez, gdzie użyto dane pochodzące z Banku Światowego. Rezultaty: Na podstawie otrzymanych wyników stwierdzono, że wskaźniki zielonej logistyki wykazują silną pozytywną korelację z zielonymi źródłami energii, przepływem FDI oraz otwartością handlu. Z drugiej strony emisja gazów cieplarnianych oraz węgla wykazuje negatywną korelację z zieloną logistyką. Dodatkowo, energia odnawialna jest wiodącym czynnikiem zielonej logistyki i operacji łańcucha dostaw, wspierającym również ekonomiczny rozwój zrównoważony. Wnioski: Praca przedstawia powiązania pomiędzy zieloną logistyką a krajowymi wskaźnikami ekonomicznymi i ekologicznymi. Dodatkowo, daje wskazówki dla praktyków, zarządzających średniego szczebla oraz politykom dla lepszego zrozumienia istotności energii odnawialnej oraz zielonych praktyk w operacjach logistycznych.

2

Effect of Air Gap Entrapped in Firefighter Protective Clothing on Thermal Resistance and Evaporative Resistance

He H., Yu Z.

Autex Research Journal

|

2018

|

Vol. 18, no. 1

28--34

EN

Heat and water vapor transfer behavior of thermal protective clothing is greatly influenced by the air gap entrapped in multilayer fabric system. In this study, a sweating hot plate method was used to investigate the effect of air gap position and size on thermal resistance and evaporative resistance of firefighter clothing under a range of ambient temperature and humidity. Results indicated that the presence of air gap in multilayer fabric system decreased heat and water vapor transfer abilities under normal wear. Moreover, the air gap position slightly influenced the thermal and evaporative performances of the firefighter clothing. In this study, the multilayer fabric system obtained the highest thermal resistance, when the air space was located at position B. Furthermore, the effect of ambient temperature on heat and water vapor transfer properties of the multilayer fabric system was also investigated in the presence of a specific air gap. It was indicated that ambient temperature did not influence the evaporative resistance of thermal protective clothing. A thermographic image was used to test the surface temperature of multilayer fabric system when an air gap was incorporated. These results suggested that a certain air gap entrapped in thermal protective clothing system could affect wear comfort.

3

Barycenter reflected equatorial Pacific sea level structure evolution and its indication of ENSO events

Luo W., Yi L., Yu Z., Sun H., Yuan L.

Oceanologia

|

2015

|

No. 57 (2)

107--115

EN

Focused on the zonal and meridional response of sea level change to El Niño-Southern Oscillation (ENSO) events, this paper retrieves the overall average, positive anomaly and negative anomaly sea surface height (SSH) series of equatorial Pacific area (EPA) from satellite altimetry data from 1993 to 2013. The barycenter method is then applied to each of the three series to get the zonal and meridional barycenter coordinates. The barycenter coordinates are then compared with the Multivariate ENSO index (MEI) to reveal the zonal and meridional response of sea level change to ENSO. The meridional and zonal spatio-temporal evolutionary processes of sea level change in EPA during different ENSO events are reconstructed by the Principle Tensor Analysis of Rank 3 Method (PTA3). Comparative analysis shows that the meridional change of positive anomalies barycenter, rather than the mean series of sea level height anomaly in EPA, can well characterize the intensity and evolutionary process of ENSO events. Meanwhile, the zonal migration of barycenter may reflect the lag adjustment of the sea level to the ENSO signal. The analysis on the meridional and zonal evolution of the sea level change in different ENSO periods shows that the response of sea level change to the ENSO events can be mainly characterized by the position differences between positive and negative sea level anomaly barycenter, SSH gradient in the meridional direction and the inconsistency in the overall spatial structure and temporal evolution characteristics in the zonal direction.

4

Study of an adaptive accelerated model and a data transfer method based on a Reliability Enhancement Test

Tao J., Yu Z., Ren Z., Yi X.

Eksploatacja i Niezawodność

|

2014

|

Vol. 16, no. 1

128--132

PL

Aby ocenić niezawodność produktu za pomocą testu poprawy niezawodności (Reliability Enhancement Test, RET), w badaniach najpierw rozważano proces zmiany parametrów modelu Arrheniusa poprzez połączenie modelu Arrheniusa z modelem Duane'a oraz przedstawiono adaptacyjny model przyspieszony i metodę oceny parametrów. Następnie, na podstawie adaptacyjnego modelu przyspieszonego opisano metodę transferu danych z RET do badań przy normalnym oddziaływaniu czynników zewnętrznych. Wreszcie, omówiono różnice obserwowane przy zastosowaniu RET do badań identyfikacyjnych niezawodności i badań wzrostu niezawodności. Na przykładzie zagadnienia inżynierskiego przedstawiono także metodę obliczania wskaźnika niezawodności produktu za pomocą RET.

EN

To assess the reliability of a product using a Reliability Enhancement Test (RET), this study first considers the change process of the Arrhenius model parameters by combining the Arrhenius model with the Duane model and gives an adaptive accelerated model and a parameter estimation method. Then, the data transfer method from the RET to normal test stress are described based on the adaptive accelerated model. Finally, the differences observed when the RET is used for a reliability identity test or a reliability growth test are discussed, and an engineering case demonstrates a method for obtaining the reliability index of a product using the RET.

5

Load-deflection relations of t-section rails under lateral loads

Song Y., Yu Z

Journal of Theoretical and Applied Mechanics

|

2013

|

Vol. 51 nr 1

195--202

EN

This paper studies the load-deflection relations of T-section rails under lateral loads based on elastic-plastic theory. A linear-hardening model and an elastic-plastic power-exponent hardening model of the material are adopted in this study. The analytical expressions for the load-deflection relations in the loading process are given. Compared with the experimental results, it is found that the load-deflection curves calculated with the elastic-plastic powerexponent hardening model are closer to the experimental results than those with the linearhardening model.

PL

W pracy zaprezentowano charakterystyki obciążeniowo-odkształceniowe obciążanych poprzecznie szyn o przekroju teowym otrzymane na podstawie teorii lepkosprężystości. W badaniach przyjęto model materiału o liniowym oraz potęgowym umocnieniu. Podano analityczne wyrażenia dla krzywych obciążenia w funkcji odkształcenia. W wyniku weryfikacji eksperymentalnej stwierdzono, że charakterystyki obciążeniowo-odkształceniowe otrzymane przy zastosowaniu modelu z potęgowym umocnieniem materiału są bliższe rezultatom doświadczalnym niż w przypadku modelu z umocnieniem liniowym.

6

Springback prediction in T-section beam bending process using neural networks and finite element method

Song Y., Yu Z.

Archives of Civil and Mechanical Engineering

|

2013

|

Vol. 13, no. 2

229--241

EN

In this paper, three point bending method is used for the T-section beam bending process. The prediction model of springback is developed using artificial neural network approach. The corresponding loading stroke that can theoretically eliminate the residual deflection of a beam after springback is determined. Application examples indicate that the proposed approach could achieve an allowable straightness error. Numerical simulations using finite element method are also performed to investigate the effect of material properties on springback. A neural network for identification of material parameters is developed by the simulation data. Besides, the residual stress distributions across the beam section are analyzed. The finite element model is validated with experimental results of springback.

7

Isometric scaling relationship between leaf number and size within current-year shoots of woody species across contrasting habitats

Li T., Deng J., Wang G., Cheng D., Yu Z.

Polish Journal of Ecology

|

2009

|

Vol. 57, nr 4

659-667

EN

The scaling relationship between the number and size of plant.s components has been observed traditionally as reflective of a trade-off in resource allocation over ontogeny. The recent finding of a negative isometric leaf size/number trade-off across 24 deciduous woody species extends knowledge of such trade-offs to current-year shoots. Before generally accepted, this isometry has to be consistent across more datasets that represent diverse habitats. We tested this scaling relationship using 12 deciduous shrub species from the western Gobi Desert and 56 woody species from the northeastern temperate zone of China. Our results showed that leaf number per stem mass of current-year shoots scaled approximately isometrically with individual leaf mass within and across habitats, which, combined with the independence of total leaf mass and individual leaf mass, supports isometric scaling for shoot-scale leaf deployment. However, the intercepts of these relationships decreased significantly along the environmental gradients, suggesting that habitats could place a constraint on the total leaf number that can be supported by a given size shoot. Convergence towards higher leaf number and smaller leaf size for some desert species suggests important adaptive implications for photosynthetic carbon gain and reproductive growth.

8

Carbon storage of cycad and other gymnosperm ecosystems in China: implications to evolutionary trends

Ma Y., Jiang H., Wang B., Zhou G., Yu S., Peng S., Hao Y., Wei X., Liu J., Yu Z.

Polish Journal of Ecology

|

2009

|

Vol. 57, nr 4 (2

635-646

EN

Cycads are an ancient lineage of plants that originated in the Permian, which are vital to the interpretation of plant ecology. The evidence in the fossil records indicates that the morphological and anatomical features of cycads are remarkably similar to the extant taxa, which has been instrumental in our understanding the connections between the early origins of seed plants and their present-day counterparts. The cycad ecosystem is an important vegetation type throughout geological time. Research on the ecological function of the cycad plays a significant role in the study of evolutionary ecology. In this study, we investigated the biomass, productivity and total carbon storage (total of vegetation, litter, and soil carbon) of cycad (Cycas panzhihuaensis L. Zhou et S.Y. Yang) ecosystems in the National C. panzhihuaensis Reserve of China (latitude 26[degrees]37', longitude 101[degrees]35', at 1635 m altitude) by applying the site-standard tree sampling harvest. Cycads are considered to be rare and endangered species, and are in the list of key protected wild plants in the world. The National C. panzhihuaensis Reserve is in Southwestern China, which area approximately 1358 ha, growing approximately 20 000 C. panzhihuaensis individuals. 20 sample plots, each 5 x 5 m were established in the spring of 2006. The mean height of cycads within the stand was 0.44 m and the mean basal diameter was 23.2 cm. The biomass and productivity data for other communities was compiled from references published over the past 20 years throughout China. The biomass and productivity of cycad ecosystems (8.102 [plus or minus] 6.880 t C ha[^-1] and 1.183 [plus or minus] 0.975 t C ha[^-1] yr[^-1], respectively) are smaller than tree fern (Alsophila spinulosa (Wall. ex Hook.) R. M. Tryon) or gymnosperm (Pinaceae, Cupressaceae or Taxodiaceae for representative) ecosystems. The community biomass of Pinaceae-, Cupressaceae- or Taxodiaceae-dominated ecosystems are 6.8, 5.4, and 5.3 times larger than the cycad ecosystem, respectively. The productivity of each is 2.3, 2.8 and 3.8 times larger than the cycad ecosystem. Cycad is an ancient dioecious plant. However, the results show that the differences between the biomass of male and female cycads, as well as the productivity, are not significant.

9

A study on interaction between ethyl violet and nucleic acids and its analytical application

Liu B., Lu L., Huang Y., Yu Z.

Chemia Analityczna

|

2009

|

Vol. 54, No. 4

733-742

EN

An interaction mechanism between ethyl violet and nucleic acids and their quantitative determination have been reported. Reaction mechanism indicated that binding of EV to yRNA proceeds mainly via electrostatic interactions and hydrogen bond formation with the phosphate groups. Resonance light scattering (RLS) of ethyl violet was greatly enhanced by nucleic acids. Based on this, ethyl violet was used as the RT,S probe for determination of nucleic acids.

PL

Opisano mechanizm oddziaływania między fioletem etylowym (EV) i kwasami nukleinowymi oraz ich ilościowe oznaczanie. Mechanizm rekacji wskazuje że wiązanie EV z yRNA zachodzi głównie przez oddziaływania elektrostatyczne i powstawanie wiązań wodorowych z grupami fosforowymi. Rezonansowe rozproszenie światła (RLS) fioletu etylowego było znacznie wzmacniane w obecności kwasów nukleinowych. Na tej podstawie fiolet etylowy zastosowano jako wskaźnik RLS do oznaczania kwasów nukleinowych.

10

On-line identification of squeeze-film dymanics of multi-mode rotor-bearing system

Yu Z., Meng L. T.

Computer Assisted Mechanics and Engineering Sciences

|

1998

|

Vol. 5, nr 3

253-266

EN

This paper presents a practical algorithm for on-line parameter identification of squeeze-film bearing of multi-mode rotor-bearing system.The identification procedure is based on modeling each of the bearing pedestal by applying a multi-frequency excitation force on the rotor and frequency transfer function data are used. It suggested that accurate identification coefficients with reduced standard errors can be achieved without resource to full or reduced-order rotor system measurements. The approach can be applied to rotor-bearing system with any degree of complexity and other types of bearing. Simulation and experimental investigation show that the identification algorithm developed in the paper will considerably simplify the measurement and calculation task for testing work in laboratory and industral environment without any lost of identification accuracy. The experimental results of stiffness and damping characteristics of the squeeze-film bearings for different rotating speed are also presented.