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Estimation of drag forces caused by natural woody vegetation of different scales

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Journal of Hydrodynamics 2014年第4期26卷 608-623页

作者： JALONEN Johanna JRVEL juha Department of Civil and Environmental Engineering Aalto University

To reliably estimate water levels and velocities in vegetated rivers and floodplains, flow resistance models based on physical plant properties are advantageous. The purpose of this study is （1） to assess the suitable parameterization of woody riparian vegetation in estimating the drag forces, （2） to address the effect of plant scale on the drag estimates and reconfiguration, and （3） to evaluate the applicability of three recently developed flow resistance models. Experiments on four tree species in a towing tank together with detailed characterization of tree properties were carried out to establish a novel dataset. Despite the variability in the tree height （0.9 m-3.4 m）, the stem, leaf and total areas proved to be suitable characteristic dimensions for estimating the flow resistance at different scales. Evaluations with independent data revealed that the tested models produced reasonable results. The performance of the models was controlled by the parameter values used rather than the model structure or the plant scale.

关键词： drag force flow resistance woody vegetation modelling

The comparison of design airflow rates with dynamic and steady-state displacement models in varied dynamic conditions

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Building Simulation 2021年第4期14卷 1201-1219页

作者： Natalia Lastovets Risto Kosonen juha Jokisalo Department of Mechanical Engineering Aalto UniversityEspooFinland College of Urban Construction Nanjing Tech UniversityNanjingChina

A temperature-based method is usually applied in displacement ventilation (DV) design when overheating is the primary indoor climate concern. Different steady-state models have been developed and implemented to calculate airflow rate in rooms with DV. However, in practical applications, the performance of DV depends on potentially dynamic parameters, such as strength, type and location of heat gains and changing heat gain schedule. In addition, thermal mass affects dynamically changing room air temperature. The selected steady-state and dynamic models were validated with the experimental results of a lecture room and an orchestra rehearsal room. Among the presented models, dynamic DV model demonstrated a capability to take into account the combination of dynamic parameters in typical applications of DV. The design airflow rate is calculated for the case studies of dynamic DV design in the modelled lecture room in both dynamic and steady-state conditions. In dynamic conditions of heavy construction in 2–4 hours occupancy periods, the actual airflow rate required could be 50% lower than the airflow rate calculated with the steady-state models. The difference between steady-state and dynamic multi-nodal model is most significant with heavyweight construction and short occupancy period (17%–28%). In cases with light construction, the dynamic DV model provides roughly the same airflow rates for four-hour occupancy period than the Mund’s model calculates. The dynamic model can significantly decrease the design airflow rate of DV, which can result in a reduction of investment costs and electrical consumption of fans.

关键词： displacement ventilation design airflow rate temperature gradient dynamic model simplified building energy models

Geometrically modeling 2D scattered points: a review of the potential for methodologically improving mobile laser scanning in data processing

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International Journal of Digital Earth 2014年第6期7卷 432-449页

作者： Yi Lin juha Hyyppa Department of Remote Sensing and Photogrammetry Finnish Geodetic Institute MasalaFinland

As a state-of-the-art mapping technology,mobile laser scanning(MLS)is increasingly applied to fields such as digital presentations of city ***,its application has recently met a bottleneck in data *** has been found that conventional methods for geometrically modeling 3D scattered points are inadequate when dealing with large volumes of MLS *** fact,this is a challenge that has already been noted in the MLS-relevant fields,*** sensing,robot perception,and pattern recognition.A variety of algorithms under the schematic frame of analysis,modeling and synthesis(AMS)have been developed in these *** AMS paradigm is to first extract the implicit geometric primitives within each scan profile by geometrically modeling its 2D scattered points(GM2P).The resultant 2D geometric primitives are then integrated to restore the real 3D geometrical *** this process,GM2P is a kernel procedure whereby a review of the GM2P algorithms is assumed to be of significance for developing new efficient algorithms for geometrically modeling 3D scattered *** idea is supported by MLS sampling often being executed via parallel scan ***,the results of the literature review indicate an avenue for methodologically improving MLS in data processing.

关键词： MLS geometrically modeling scattered points GM2P AMS scan profile

Variation in the timing of river entry of Atlantic salmon (Salmo salar L.) in the Baltic

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Current Zoology 2009年第5期55卷 342-349页

作者： Anna KUPARINEN juha MERIL Department of Biological and Environmental Sciences

The timing of river entry in the Atlantic salmon is known to depend on genetic, demographic and environmental factors, but little is known about the relative magnitude of among population and among year variation and covariation in this respect in natural state Atlantic salmon rives. To investigate this, variability in the timing of river entry in three historical Finnish Atlantic salmon populations were analyzed using salmon trap data collected during 1870- 1902. The analyses reveled that 1 ） the timing of river entry differed substantially and consistently among the rivers, and that 2） variation among the rivers was much larger than variation among years. Annual variations were not explained by regional environmental conditions, whereas in one river the timing of the local flood peak was a significant predictor of the timing of river entry. Differences in the timing of salmon entry to geographically closely situated rivers suggests that a regionally fixed opening date for coastal fisheries might not be the best management strategy as it may lead to uneven exploitation of salmon populations from different rivers [ Current Zoology 55 （5）： 342 - 349, 2009] .

关键词： Atlantic salmon Coastal fisheries Fisheries management Freshwater entry Migration River entry

Fluid dynamic modeling of a free piston engine with labyrinth seals

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Journal of Thermal Science 2010年第2期19卷 141-147页

作者： Jaakko Larjola juha Honkatukia Petri Sallinen Jari Backman Lappeenranta University of Technology P.O.Box 2053851 Lappeenranta

Preliminary design and simulation of a free piston engine suitable for small-scale energy production in distributed energy systems is presented in this *** properties,particularly the properties of gas seals of the engine are simulated using a simulation program developed for this case,and the results are utilized in preliminary main design parameter *** engine simulation program was developed by combining and modifying the source codes of the simulation and calculation programs obtained from Helsinki University of Technology,Tampere University of Technology,and Lappeenranta University of *** of the contact-free labyrinth seal used in the piston,the efficiency of the motor is lower than the efficiency of a conventional motor with oil lubricated piston *** the other hand,the lack of bearing losses,and the lack of losses associated with a crankshaft system and a gearbox,as well as the lack of lubrication oil expenses,compensates this *** a net result,this new motor would perform slightly better than the conventional *** completely oil-free,it is very environmentally friendly,and its exhaust gases are completely free of oil residuals which are causing problems in normal gas motors.

关键词： free piston engine distributed energy systems simulation labyrinth seal

Feasibility of Pulse Combustion in Micro Gas Turbines

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Journal of Thermal Science 2012年第5期21卷 466-473页

作者： juha Honkatukia Esa Saari Timo Knuuttila Jaakko Larjola Jari Backman Lappeenranta University of Technology P.O. Box 2053851 Lappeenranta Finland T-Turbine Oy Rakentajainkuja 4 B02330 Espoo Finland

In gas turbines, a fast decrease of efficiency appears when the output decreases; the efficiency of a large gas tur-bine （20...30 MW） is in the order of 40 %, the efficiency of a 30 kW gas turbine with a recuperator is in the order of 25 %, but the efficiency of a very small gas turbine （2...6 kW） in the order of 4...6 % （or 8... 12 % with an op- timal recuperator）. This is mainly a result of the efficiency decrease in kinetic compressors, due to the Reynolds number effect. Losses in decelerating flow in a flow passage are sensitive to the Reynolds number effects. In con- trary to the compression, the efficiency of expansion in turbines is not so sensitive to the Reynolds number; very small turbines are made with rather good efficiency because the flow acceleration stabilizes the boundary layer. This study presents a system where the kinetic compressor of a gas turbine is replaced with a pulse combustor. The combustor is filled with a combustible gas mixture, ignited, and the generated high pressure gas is expanded in the turbine. The process is repeated frequently, thus producing a pulsating flow to the turbine; or almost a uni- form flow, if several parallel combustors are used and triggered a/ternately in a proper way. Almost all the com- pression work is made by the temperature increase from the combustion. This gas turbine type is investigated theoretically and its combustor also experimentally with the conclusion that in a 2 kW power size, the pulse flow gas turbine is not as attractive as expected due to the big size and weight of parallel combustors and due to the ef- ficiency being in the order of 8 % to 10 %. However, in special applications having a very low power demand, below 1000 W, this solution has better properties when compared to the conventional gas turbine and it could be worth of a more detailed investigation.

关键词： Gas turbine pulse combustion micro size low Reynolds number

Inhibition and enhancement of neural regeneration by chondroitin sulfate proteoglycans

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Neural Regeneration Research 2017年第5期12卷 687-691页

作者： Heikki Rauvala Mikhail Paveliev juha Kuja-Panula Natalia Kulesskaya Neuroscience Center University of Helsinki Helsinki Finland Department of Biological and Environmental Sciences University of Helsinki Helsinki Finland

The current dogma in neural regeneration research implies that chondroitin sulfate proteoglycans（CSPGs） inhibit plasticity and regeneration in the adult central nervous system（CNS）. We argue that the role of the CSPGs can be reversed from inhibition to activation by developmentally expressed CSPG-binding factors. Heparin-binding growth-associated molecule（HB-GAM; also designated as pleiotrophin） has been studied as a candidate molecule that might modulate the role of CSPG matrices in plasticity and regeneration. Studies in vitro show that in the presence of soluble HB-GAM chondroitin sulfate（CS） chains of CSPGs display an enhancing effect on neurite outgrowth. Based on the in vitro studies, we suggest a model according to which the HB-GAM/CS complex binds to the neuron surface receptor glypican-2, which induces neurite growth. Furthermore, HB-GAM masks the CS binding sites of the neurite outgrowth inhibiting receptor protein tyrosine phosphatase sigma（PTPσ）, which may contribute to the HB-GAM-induced regenerative effect. In vivo studies using two-photon imaging after local HB-GAM injection into prick-injury of the cerebral cortex reveal regeneration of dendrites that has not been previously demonstrated after injuries of the mammalian nervous system. In the spinal cord, two-photon imaging displays HB-GAM-induced axonal regeneration. Studies on the HB-GAM/CS mechanism in vitro and in vivo are expected to pave the way for drug development for injuries of brain and spinal cord.

关键词： CNS injury axon regeneration dendrite regeneration proteoglycans aggrecan glypican HB-GAM pleiotrophin PTEN

Carbonic anhydrases in normal gastrointestinal tract and gastrointestinal tumours

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World Journal of Gastroenterology 2005年第2期11卷 155-163页

作者： Antti J. Kivel Jyrki Kivel juha Saarnio Seppo Parkkila Department of Anatomy and Cell Biology University of OuluFinland Institute of Medical TechnologyUniversity of Tampere and Tampere University HospitalFinland Institute of Dentistry University of HelsinkiFinlandResearch Institute of Military MedicineCentral Military HospitalHelsinkiFinland Department of Surgery University of OuluFinland Institute of Medical Technology University of Tampere and Tampere University HospitalFinland Department of Clinical ChemistryUniversity of OuluFinland

Carbonic anhydrases (CAs) catalyse the hydration of C02 to bicarbonate at physiological pH. This chemical interconversion is crucial since HCO3- is the substrate for several biosynthetic reactions. This review is focused on the distribution and role of CA isoenzymes in both normal and pathological gastrointestinal (GI) tract tissues. It has been known for many years that CAs are widely present in the GI tract and play important roles in several physiological functions such as production of saliva, gastric acid, bile, and pancreatic juice as well as in absorption of salt and water in intestine. New information suggests that these enzymes participate in several processes that were not envisioned earlier. Especially, the recent reports on plasma membrane-bound isoenzymes IX and XII have raised considerable interest since they were reported to participate in cancer invasion and spread. They are induced by tumour hypoxia and may also play a role in von Hippel-Lindau (VHL)-mediated carcinogenesis.

关键词： Gastrointestinal tract Gastrointestinal tumour Carbonic anhydrases

Systemic inflammation in colorectal cancer: Underlying factors,effects, and prognostic significance

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World Journal of Gastroenterology 2019年第31期25卷 4383-4404页

作者： Anne E Tuomisto Markus J Makinen juha P Vayrynen Cancer and Translational Medicine Research Unit University of OuluOulu 90220Finland Department of Pathology Oulu University Hospital and Medical Research Center OuluOulu 90220Finland Department of Medical Oncology Dana-Farber Cancer Institute and Harvard Medical SchoolBostonMA 02115United States

Systemic inflammation is a marker of poor prognosis preoperatively present in around 20%-40%of colorectal cancer *** hallmarks of systemic inflammation include an increased production of proinflammatory cytokines and acute phase proteins that enter the *** the low-level systemic inflammation is often clinically silent,its consequences are many and may ultimately lead to chronic cancer-associated wasting,*** this review,we discuss the pathogenesis of cancer-related systemic inflammation,explore the role of systemic inflammation in promoting cancer growth,escaping antitumor defense,and shifting metabolic pathways,and how these changes are related to less favorable outcome.

关键词： Colorectal cancer Inflammation Prognosis Cytokine Chemokine C-reactive protein Glasgow prognostic score Cachexia Metastasis