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21.
彭丹 《艺术与设计.数码设计》2007,(1)
广告和CI作为一种信息和视觉传递形式,在对现代企业的发展中起着重要作用。这已经是无可非议的事实了。文章首先叙述广告和CI的概念,以及两者分别对现代企业发展的作用,然后分析两者之间的不同点、相同点以及相辅相成的关系,充分注意两者之间相互促进、相互强化、而又相互制约,共同为企业的发展发挥巨大作用。 相似文献
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给出了1998年在上海交通大学举行的第7届全国青年计算机学术会议上青年计算机学者提出的一些当前中国计算机领域面临的问题以及对策。 相似文献
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Many short-run studies point to the potential for direct fueling of compression ignition engines with plant oil fuels. There is a much smaller body of work that examines the potential for these fuels in long-run tests that illuminate engine endurance and longevity issues. Generally, longevity studies involving direct fueling of engines with straight plant oils have shown significant impact to the life of the engine, though test results vary widely depending on the oil, engine type, test conditions, and measurement approach. This study utilizes a previously designed modification kit [1] to investigate the longevity implications of directly fueling straight plant oil in an indirect injection (IDI) listeroid type, slow speed stationary engine common in agro-processing applications in developing countries. Specifically this study focuses on the lubrication oil by developing a model to characterize the engine wear and estimate lube oil change frequency. The model is extended to an analysis of the piston rings. Cylinder liner wear, emissions, engine performance, and a visual investigation of several critical engine components are also studied. 相似文献
26.
M. Heck H.M. Ortner S. Flege U. Reuter W. Ensinger 《International Journal of Refractory Metals and Hard Materials》2008,26(3):197-206
Compacted graphite iron (CGI) is the material for the upcoming new generation of high-power diesel engines. Due to its increased strength compared to grey cast iron (CI) it allows an increase in the cylinder-pressures and therefore a better fuel economy and a higher power output are possible. First examples of such engines are the 3.3 L Audi V8 TDI and the 4.0 L BMW V8. The reason why CGI is not used to a larger extent in large scale production up to now is its much more difficult machinability as compared to conventional CI, especially at high cutting speeds. In modern transfer lines high cutting speeds are used in the cylinder-boring operation. And especially in these continuous cutting operations the tool life decreased due to the change from CI to CGI by about a factor of 20. As was found out previously by us, the difference in tool lifetime can be explained by the formation of a MnS-layer on the tool surface in the case of CI. This layer cannot form when machining CGI because the formation of MnS-inclusions is not possible in this material due to the higher magnesium content which in turn is responsible for the formation of the graphite vermicles. The MnS-layer acts as a lubricant and prevents the adhesion of workpiece particles. This is the reason for the greatly reduced wear of CI in high speed machining operations. This MnS-layer is inspected closer by X-ray diffraction, X-ray induced photoelectron spectrometry, atomic force microscopy and secondary ion mass spectrometry in this work. Furthermore, available information on the performance of MnS as lubricant in PM-steels is comparatively discussed. This knowledge led to an economic solution of high productivity machining of CGI. The key was to reduce the cutting speed, replacing single insert tools with multiple insert tools. This allowed to increase the feed rate. By increasing the feed rate in the same amount as decreasing the cutting speed, the same productivity can be realized. This concept is leading to a number of multiple insert tools thus realizing a high productivity machining of CGI cylinder-bores with multi-layer-coated carbide tools. 相似文献
27.
Kathrin Strebel Ulrike Rolle-Kampczyk Annegret Kindler Uwe Schlink 《The Science of the total environment》2010,408(18):3931-3942
This paper presents an investigation into spatial risk differences over small distances for the Helicobacter pylori infection in the city of Leipzig, Germany and two rural districts. A model, using Bayesian inference, was developed that adjusts the risk for individual-specific factors, and for spatial or individual over-dispersion, respectively. Additionally, the model takes into account conditional spatial autocorrelation. We found a significant positive association to the H. pylori infection risk for: “more than three children live in the household” (OR = 2.4, p = 0.001), “more persons live per sq.m than average” (OR = 1.4, p = 0.03), “home situated at main road” (OR = 1.4, p = 0.04) and “using well water” (OR = 2.3, p = 0.05). A protective effect was identified for “travelled to low prevalence region” (OR = 0.4, p < 0.0001) and “born in Germany” (OR = 0.2, p < 0.0001). Three administrative areas with significantly increased spatial risk were identified: one in the rural district and two in the city of Leipzig. The model explained 24.9% of the total deviance. Contrary to expectations, the largest part of deviance of the data was not explained by the identified significant risk factors, but by individual-specific heterogeneities. We conclude that further - so far not discussed - factors influence the risk and the spatial variation of the H.pylori infection. Furthermore, from the results we speculate about a possible impact of long-time air pollution and surface water. 相似文献
28.
Lubica Sobotova Jana Jurkovicova Ludmila Sevcikova 《The Science of the total environment》2010,408(6):1264-1270
Objective
The objective of our study was to investigate and evaluate the relationship between road traffic noise and cardiovascular risk.Methods
The study sample (n = 659; 36.9% male, 63.1% female university students, mean age 22.83 ± 1.58 years) included a group exposed to road traffic noise (n = 280, Leq,24 h = 67 ± 2 dB(A)) and a control group (n = 379, Leq,24 h = 58.7 ± 6 dB(A)). Subjective response was determined by a validated noise annoyance questionnaire. The ten year risk of developing a coronary heart disease event was quantified as an evaluation of cardiovascular risk (SCORE60, Framingham 10-year risk estimation and projection to the age of 60, relative risk SCORE chart).Results
Cardiovascular risk scores were significantly higher in the exposed group based on the Framingham scores projected to the age of 60, SCORE60 (AOR = 2.72 (95% CI = 1.21-6.15)) and the relative risk SCORE chart (AOR = 2.81 (1.46-5.41)).Conclusions
These findings highlight the association between road traffic noise and cardiovascular risk. 相似文献29.
Yuming Guo Shilu Tong Adrian G. Barnett Xiaochuan Pan 《The Science of the total environment》2010,408(20):4446-1817
Background
A number of epidemiological studies have examined the adverse effect of air pollution on mortality and morbidity. Also, several studies have investigated the associations between air pollution and specific-cause diseases including arrhythmia, myocardial infarction, and heart failure. However, little is known about the relationship between air pollution and the onset of hypertension.Objective
To explore the risk effect of particulate matter air pollution on the emergency hospital visits (EHVs) for hypertension in Beijing, China.Methods
We gathered data on daily EHVs for hypertension, fine particulate matter less than 2.5 μm in aerodynamic diameter (PM2.5), particulate matter less than 10 μm in aerodynamic diameter (PM10), sulfur dioxide, and nitrogen dioxide in Beijing, China during 2007. A time-stratified case-crossover design with distributed lag model was used to evaluate associations between ambient air pollutants and hypertension. Daily mean temperature and relative humidity were controlled in all models.Results
There were 1,491 EHVs for hypertension during the study period. In single pollutant models, an increase in 10 μg/m3 in PM2.5 and PM10 was associated with EHVs for hypertension with odds ratios (overall effect of five days) of 1.084 (95% confidence interval (CI): 1.028, 1.139) and 1.060% (95% CI: 1.020, 1.101), respectively.Conclusion
Elevated levels of ambient particulate matters are associated with an increase in EHVs for hypertension in Beijing, China. 相似文献30.
Concentrations and determinants of organochlorine levels among pregnant women in Eastern Spain 总被引:1,自引:0,他引:1
Sabrina Llop Ferran Ballester Esther Vizcaino Maria-Jose Lopez-Espinosa Marisa Rebagliato Alfredo Marco Joan O. Grimalt 《The Science of the total environment》2010,408(23):5758-5767
Persistent organic pollutants (POPs) comprise a large variety of toxic substances with ample distribution. While exposure to these toxins occurs mainly through diet, maternal POP levels may be influenced by certain sociodemographic, environmental, or lifestyle factors. This is important given that these substances may have adverse effects on fetal development. The aim of this study is to examine the sociodemographic, environmental, lifestyle, and dietary determinants of the levels of hexachlorobenzene (HCB), b-hexachlorocyclohexane (b-HCH), 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (4,4′-DDT), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (4,4′-DDE), and polychlorinated biphenyls (PCB congeners 118, 138, 153, 180) measured in the blood of pregnant women participating in a mother-child cohort study conducted in Valencia (Spain).The study population consisted of 541 pregnant women who formed part of the INMA (Childhood and the Environment) cohort (2004-2006). POP levels were determined in blood taken during the 12th week of pregnancy with the aid of gas chromatography with electron capture detection. Sociodemographic, environmental, and dietary information was obtained from a questionnaire. Multivariate Tobit regression models were constructed in order to assess the association between POP levels and selected covariates.The results showed that all the women had detectable levels of at least one of these compounds while in 43% of the subjects, all eight compounds were detected. The compounds found in the greatest number of women were 4,4′-DDE (100%) and PCBs 153 and 180 (95%). The most important determinants of high POP levels were the mother's age, country of origin, increased body mass index, and number of weeks of breastfeeding after previous pregnancies. With regard to diet, 4,4′-DDT and 4,4′-DDE levels increased with the intake of meat, fruit, and cereal. PCB 153 levels increased with the intake of seafood. The levels of HCB, b-HCH, 4,4′-DDT, and 4,4′-DDE observed in this study were slightly higher than in other studies, whereas the PCB levels were similar. 相似文献