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排序方式: 共有204条查询结果,搜索用时 15 毫秒
1.
Joel Kuula Heino Kuuluvainen Jarkko V. Niemi Erkka Saukko Harri Portin Anu Kousa 《Aerosol science and technology》2020,54(2):190-202
AbstractLung deposited surface area (LDSA) is a relatively new metric that has been argued to be more accurate at predicting health effects from aerosol exposure. For typical atmospheric aerosol, the LDSA concentration depends mainly on the concentration of ultrafine particles (e.g. vehicular exhaust emissions and residential wood combustion) and therefore optical methods cannot be used to measure and quantify it. The objective of this study was to investigate and describe typical characteristics of LDSA under different urban environments and evaluate how a diffusion charging-based Pegasor AQ Urban sensor (Pegasor Ltd., Finland) can be used as an alternative to optical sensors when assessing local combustion emissions and respective LDSA concentrations. Long-term (12?months) sensor measurements of LDSA were carried out at three distinctly different measurement sites (four sensor nodes) in the Helsinki metropolitan area, Finland. The sites were affected mainly by vehicular exhaust emission (street canyon and urban background stations) and by residential wood combustion (two detached housing area stations). The results showed that the accuracy of the AQ Urban was good (R2 = 0.90) for the measurement of LDSA when compared to differential mobility particle sizer. The mean concentrations of LDSA were more than twice as high at the street canyon (mean 22 µm2 cm?3) site when compared to the urban background site (mean 9.4 µm2 cm?3). In the detached housing area, the mean concentrations were 12 µm2 cm?3, and wood combustion typically caused high LDSA peaks in the evenings. High correlations and similar diurnal cycles were observed for the LDSA and black carbon at street canyon and urban background stations. The utilization of a small-scale sensor network (four nodes) showed that the cross-station variability in hourly LDSA concentrations was significant in every site, even within the same detached housing area (distance between the two sites ~670?m). 相似文献
2.
An expenmental and theoretical study of heat and mass transfer analogy and a comparison of that to a binary liquid mixture evaporation is presented. Common organic solvents, ethanol and n-heptane, were used to form an alcohol - hydrocarbon mixture. Studies were carried out in a horizontal rectangular channel having air flow velocities of 0.2 - 0.9 m/s. Heat transfer coefficients were measured with a copper plate resistor and mass transfer coefficients with a square pool. The heat and mass transfer analogy is presented for a system having two evaporating compounds with a fixed value of air flow and verified by measuring and comparing mass transfer coefficients for distilled water with air flow velocities of 0.2 - 0.9 mls. An illustrative example of the use of the theory for industrial ventilation is presented. 相似文献
3.
Faisal Ahmed Carlos Rodríguez-Fernández Henry A. Fernandez Yi Zhang Abde Mayeen Shafi Md Gius Uddin Xiaoqi Cui Hoon Hahn Yoon Naveed Mehmood Andreas C. Liapis Lide Yao Humeyra Caglayan Zhipei Sun Harri Lipsanen 《Advanced functional materials》2023,33(33):2302051
Developing selective and coherent polymorphic crystals at the nanoscale offers a novel strategy for designing integrated architectures for photonic and optoelectronic applications such as metasurfaces, optical gratings, photodetectors, and image sensors. Here, a direct optical writing approach is demonstrated to deterministically create polymorphic 2D materials by locally inducing metallic 1T′-MoTe2 on the semiconducting 2H-MoTe2 host layer. In the polymorphic-engineered MoTe2, 2H- and 1T′- crystalline phases exhibit strong optical contrast from near-infrared to telecom-band ranges (1–1.5 µm), due to the change in the band structure and increase in surface roughness. Sevenfold enhancement of third harmonic generation intensity is realized with conversion efficiency (susceptibility) of ≈1.7 × 10−7 (1.1 × 10−19 m2 V−2) and ≈1.7 × 10−8 (0.3 × 10−19 m2 V−2) for 1T′ and 2H-MoTe2, respectively at telecom-band ultrafast pump laser. Lastly, based on polymorphic engineering on MoTe2, a Schottky photodiode with a high photoresponsivity of 90 AW−1 is demonstrated. This study proposes facile polymorphic engineered structures that will greatly benefit realizing integrated photonics and optoelectronic circuits. 相似文献
4.
Tuomas Haggren Ali Shah Anton Autere Joona-Pekko Kakko Veer Dhaka Maria Kim Teppo Huhtio Zhipei Sun Harri Lipsanen 《Nano Research》2017,10(8):2657-2666
Light management and electrical isolation are essential for the majority of optoelectronic nanowire (NW) devices.Here,we present a cost-effective technique,based on vapor-phase deposition of parylene-C and subsequent annealing,that provides conformal encapsulation,anti-reflective coating,improved optical properties,and electrical insulation for GaAs nanowires.The process presented allows facile encapsulation and insulation that is suitable for any nanowire structure.In particular,the parylene-C encapsulation functions as an efficient antireflection coating for the nanowires,with reflectivity down to <1% in the visible spectrum.Furthermore,the parylene-C coating increases photoluminescence intensity,suggesting improved light guiding to the NWs.Finally,based on this process,a NW LED was fabricated,which showed good diode performance and a clear electroluminescence signal.We believe the process can expand the fabrication possibilities and improve the performance of optoelectronic nanowire devices. 相似文献
5.
Adam Kłodowski Timo Rantalainen Aki Mikkola Ari Heinonen Harri Sievänen 《Multibody System Dynamics》2011,25(4):395-409
A method for bone strain estimation is examined in this article. The flexibility of a single bone in an otherwise rigid human
skeleton model has been studied previously by various authors. However, in the previous studies, the effect of the flexibility
of multiple bones on the musculoskeletal model behavior was ignored. This study describes a simulation method that can be
used to estimate the bone strains at both tibias and femurs of a 65-year-old Caucasian male subject. The verification of the
method is performed by the comparison of the results with other studies available in literature. The results of the study
show good correlation with the results of previous empirical studies. A damping effect of the flexible bones on the model
is also studied in this paper. 相似文献
6.
Harri Tuomisto Petra Lundstrm Ritva Korhonen Jzsef Elter Milan Hladký Jozef Tomek Ludovít Fagula 《Nuclear Engineering and Design》2003,221(1-3):181
There are twelve operating VVER-440/213 reactors in the Czech Republic, Hungary and Slovakia. The plant owners have carried out extensive safety enhancement programmes, which have included measures to improve prevention, mitigation and control of design basis accidents. Recently, there have been a number of projects to study the Severe Accident Management aspects of these plants. The plant owners have also initiated Plant Life Management programmes. The objective of the VERSAFE Concerted Action is to create a network of the VVER-440/213 plant owners and operators, which aims at definition of the further research needs of severe accidents and plant ageing from the utilities’ viewpoint. The starting point is to formulate a general approach to severe accident management and plant life management and then proceed to define the needs for the additional information expected from the safety research. The role of national research institutes and organisations of the partner countries is of crucial importance in performing such research and, thus, creating and maintaining the expertise on the national level. The successful completion of the project will assist in establishing well-defined research projects that are oriented to the needs of the end-users and provide information that can be used to facilitate and support the negotiations of the EU applicant countries operating VVER-440 reactors. 相似文献
7.
Siet J. Sijtsema Katarzyna Jesionkowska Ronan Symoneaux Dorota Konopacka Harriëtte Snoek 《LWT》2012,49(2):275-281
Dried fruits consumption has not received much research attention, although these foods are associated with potential health benefits. Therefore, the aim of this study was to compare fresh fruits and dried fruits on measures of health, convenience and consumer feelings.An on-line questionnaire that measured consumers' perceptions of the health benefits and convenience characteristics and their feelings about the consumption of both fresh fruits (apples and plums) and dried fruits (e.g., raisins, dates, and apricots) was completed by 693 respondents (Polish, French, and Dutch).Generally, fresh fruits were perceived to be healthier and less convenient than dried fruits. Consumers also reported more positive feelings about the consumption of fresh fruits compared to dried fruits. The more that the respondents were willing to sacrifice for their health, the more positively they rated the health aspects of both fresh and dried fruits, as well as several perceptions of convenience of both fresh and dried fruits. Health preoccupation was unrelated to most of the convenience perceptions and was associated with lower scores on several perceptions of healthiness. Recommendations for the consumer-oriented development of dried fruits are also provided. 相似文献
8.
9.
Peltokoski Merja Eskelinen Harri 《The International Journal of Advanced Manufacturing Technology》2018,99(9-12):2137-2148
Effective production in a networking environment of sheet metal products needs accurate and relevant PDM (product data management) data, appropriate modeling of components supported by local and global network solutions, and utilization of advantages of feature-based modeling. To enable these aspects of effective production in sheet metal production, it is necessary to evaluate the integration of DFMA (design for manufacturing and assembly) and PDM. This paper aims at identifying the challenges of DFMA and PDM integration through recognizing possible malfunctioning parts of their integration. The observations are based on sheet metal specimens in which the DFMA and PDM aspects are visible in punching and bending. This study will focus on five issues that are included either in DFMA or PDM, or both: the effects of different calculation methods for the flattened length, utilization viewpoints of global or local manufacturability guidelines, assembly conditions, options to tune the manufacturing process instead of changing the product geometry, and possible additional requirements given by the customers. Based on practical design and manufacturing tests, it has become evident that one option to improve the quality of analyzed sheet metal parts is to further develop the integration of DFMA features with the workshop’s cutting and punching parameters. As one possible improvement to these kinds of integration tasks of DFMA and PDM, it is suggested that the responsibilities for developing DMFA and PDM applications with proper design parameters could be analyzed more deeply between persons working with information exchange, product design, software design, or production machine design. 相似文献
10.
Jonas Sidaravicius Ringaudas Rinkūnas Justinas Jurksus Tadeus Lozovski Isto Heiskanen Kaj Backfolk 《应用聚合物科学杂志》2014,131(22)
The number of polymers successfully electrospun is increasing, and methods are needed predict the electrospinnability of polymers. With such methods, researchers should consider the polymer solution parameters and perform measurements in conditions that mimic the electrospinning process. A novel test method based on the electromechanical simulation of the fiber formation was developed. We formed fibers by mechanically dragging a conductive ball from the solution at an applied voltage and measuring the electrical current. The changes in the time of the electrical current (the ball current) reflect the fiber‐formation process, which depended on certain polymer solution properties (e.g., viscosity, surface tension, liquid flow) and on the influence of charges on the fiber surface. The data obtained with the proposed method was compared with experimental data from electrospinning trials with the spinneret and bubble electrospinning. The results demonstrate that the ball‐current method made it possible to predict the polymer solution behavior in the electrospinning process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41091. 相似文献