953 resultados para Elongation at break
Resumo:
Weldability of powder bed fusion (PBF) fabricated components has come to discussion in past two years due to resent developments in the PBF technology and limited size of the machines used in the fabrication process. This study concentrated on effects of energy input of welding on mechanical properties and microstructural features of welds between PBF fabricated stainless steel 316L sheets and cold rolled sheet metal of same composition by the means of destructive testing and microscopic analysis. Optical fiber diameter, laser power and welding speed were varied during the experiments that were executed following one variable at a time (OVAT) method. One of the problems of welded PBF fabricated components has been lower elongations at break comparing to conventionally manufactured components. Decreasing energy input of the laser keyhole welding decreased elongations at break of the welded specimens. Ultimate tensile strengths were not affected significantly by the energy input of the welding, but fracturing of the specimens welded using high energy input occurred from the weld metal. Fracturing of the lower energy input welds occurred from the PBF fabricated base metal. Energy input was found to be critical factor for mechanical properties of the welds. Multioriented grain growth and formation of neck at fusion zone boundary on the cold rolled side of the weld was detected and suspected to be result from weld pool flows caused by differences in molten weld pool behaviour between the PBF fabricated and cold rolled sides of the welds.
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Sphingolipids are widely expressed molecules, which traditionally were considered to have majorly structural properties. Nowadays, however, they are implicated in a wide range of different biological processes. The bioactive lipid sphingosine 1-phosphate (S1P) has emerged during the past decade as one of the most studied molecules due to its proliferative and pro-migratory abilities both during normal physiology and in the pathology of a subset of different diseases. Migration and invasion of cancer cells require changes in cell behavior and modulation of the tissue microenvironment. Tumor aggressiveness is markedly enhanced by hypoxia, in which hypoxia inducible transcription factors 1-2α (HIF-1-2α) are activated to promote metabolism, proliferation and migration. Invasion requires degradation of the extracellular matrix (ECM) achieved by several degrading and remodeling enzymes. Matrix metalloproteinases (MMPs) are broadly expressed and well accepted as proteolytic enzymes with essential roles both in normal physiology and in pathology. Previously, S1P was shown to strongly evoke migration of follicular ML-1 thyroid cancer cells. The objective of this study was to further investigate and understand the mechanisms behind this regulation. In the first project it was demonstrated that S1P enhances the expression and activity of HIF-1α. S1P enhanced the expression of HIF-1α by increasing its synthesis and stability. The S1P-increased HIF-1α was mediated via S1P3, Gi/0, PI3K, PKCβI, ERK1/2, mTOR and translation factors p70S6K and eIF4E. Finally, it was shown that HIF-1α mediated S1P-induced migration. The ECM is constituted of a complex and coordinated assembly of many types of proteins. In order to be able to invade, cells need to break down the ECM, therefore several key players in this event were investigated in the second project. S1P increased the secretion and activity of MMP2 and MMP9 via S1P-receptor 1 and 3 and that these MMPs participated in the S1P-facilitated invasion of ML-1 cells. In this interplay, calpains and Rac1 were involved, both of which are crucial players in migration and invasion. The prognosis for some types of thyroid cancer is relatively good. However, there are forms of thyroid cancers, for which there are no treatments or the current available treatments are inefficient. Thus, new medical interventions are urgently needed. In the third project the significance of the S1P-receptor modulating drug FTY720, which is currently used for the treatment of multiple sclerosis (MS), was studied. The effect of FTY720 was tested on several thyroid cancer cell lines, and it inhibited the proliferation and invasion of all cancer cell lines tested. In ML-1 cells, FTY720 attenuated invasion by blocking signaling intermediates important for migration and invasion of the cells. Moreover, FTY720 inhibited the proliferation of ML-1 cells by increasing the expression of p21 and p27, hence, inducing cell arrest in G1 phase of the cell cycle. Thus, it can be suggested that FTY720 could be used in the treatment of thyroid cancer.
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Laser cutting implementation possibilities into paper making machine was studied as the main objective of the work. Laser cutting technology application was considered as a replacement tool for conventional cutting methods used in paper making machines for longitudinal cutting such as edge trimming at different paper making process and tambour roll slitting. Laser cutting of paper was tested in 70’s for the first time. Since then, laser cutting and processing has been applied for paper materials with different level of success in industry. Laser cutting can be employed for longitudinal cutting of paper web in machine direction. The most common conventional cutting methods include water jet cutting and rotating slitting blades applied in paper making machines. Cutting with CO2 laser fulfils basic requirements for cutting quality, applicability to material and cutting speeds in all locations where longitudinal cutting is needed. Literature review provided description of advantages, disadvantages and challenges of laser technology when it was applied for cutting of paper material with particular attention to cutting of moving paper web. Based on studied laser cutting capabilities and problem definition of conventional cutting technologies, preliminary selection of the most promising application area was carried out. Laser cutting (trimming) of paper web edges in wet end was estimated to be the most promising area where it can be implemented. This assumption was made on the basis of rate of web breaks occurrence. It was found that up to 64 % of total number of web breaks occurred in wet end, particularly in location of so called open draws where paper web was transferred unsupported by wire or felt. Distribution of web breaks in machine cross direction revealed that defects of paper web edge was the main reason of tearing initiation and consequent web break. The assumption was made that laser cutting was capable of improvement of laser cut edge tensile strength due to high cutting quality and sealing effect of the edge after laser cutting. Studies of laser ablation of cellulose supported this claim. Linear energy needed for cutting was calculated with regard to paper web properties in intended laser cutting location. Calculated linear cutting energy was verified with series of laser cutting. Practically obtained laser energy needed for cutting deviated from calculated values. This could be explained by difference in heat transfer via radiation in laser cutting and different absorption characteristics of dry and moist paper material. Laser cut samples (both dry and moist (dry matter content about 25-40%)) were tested for strength properties. It was shown that tensile strength and strain break of laser cut samples are similar to corresponding values of non-laser cut samples. Chosen method, however, did not address tensile strength of laser cut edge in particular. Thus, the assumption of improving strength properties with laser cutting was not fully proved. Laser cutting effect on possible pollution of mill broke (recycling of trimmed edge) was carried out. Laser cut samples (both dry and moist) were tested on the content of dirt particles. The tests revealed that accumulation of dust particles on the surface of moist samples can take place. This has to be taken into account to prevent contamination of pulp suspension when trim waste is recycled. Material loss due to evaporation during laser cutting and amount of solid residues after cutting were evaluated. Edge trimming with laser would result in 0.25 kg/h of solid residues and 2.5 kg/h of lost material due to evaporation. Schemes of laser cutting implementation and needed laser equipment were discussed. Generally, laser cutting system would require two laser sources (one laser source for each cutting zone), set of beam transfer and focusing optics and cutting heads. In order to increase reliability of system, it was suggested that each laser source would have double capacity. That would allow to perform cutting employing one laser source working at full capacity for both cutting zones. Laser technology is in required level at the moment and do not require additional development. Moreover, capacity of speed increase is high due to availability high power laser sources what can support the tendency of speed increase of paper making machines. Laser cutting system would require special roll to maintain cutting. The scheme of such roll was proposed as well as roll integration into paper making machine. Laser cutting can be done in location of central roll in press section, before so-called open draw where many web breaks occur, where it has potential to improve runability of a paper making machine. Economic performance of laser cutting was done as comparison of laser cutting system and water jet cutting working in the same conditions. It was revealed that laser cutting would still be about two times more expensive compared to water jet cutting. This is mainly due to high investment cost of laser equipment and poor energy efficiency of CO2 lasers. Another factor is that laser cutting causes material loss due to evaporation whereas water jet cutting almost does not cause material loss. Despite difficulties of laser cutting implementation in paper making machine, its implementation can be beneficial. The crucial role in that is possibility to improve cut edge strength properties and consequently reduce number of web breaks. Capacity of laser cutting to maintain cutting speeds which exceed current speeds of paper making machines what is another argument to consider laser cutting technology in design of new high speed paper making machines.
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Calcium bioavailability of raw and extruded amaranth grains was assessed in a biological assay in rats. Rats were fed for 28 days on diets in which raw or extruded amaranth was the only calcium source, compared to a control diet with calcium carbonate. Calcium and phosphorous levels were determined in the rats' serum during the experimental period and in the bones at the end of the experiment. Amaranth extrusion increased its calcium bioavailability, assessed by tibia and femur weights and calcium and phosphorous content of the bones. Apparent calcium absorption index, the force needed to break the bones and bone densitometry of both extruded and raw amaranth were the same, though different from the control group. The results show that amaranth can be a complementary source of dietary calcium the bioavailability of which is favorably modified by the extrusion process.
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Mimic biological structures such as the cell wall of plant tissues may be an alternative to obtain biodegradable films with improved mechanical and water vapor barrier properties. This study aims to evaluate the mechanical properties and water vapor permeability (WVP) of films produced by using the solvent-casting technique from blended methylcellulose, glucomannan, pectin and gelatin. First, films from polysaccharides at pH 4 were produced. The film with the best mechanical performance (tensile strength = 72.63 MPa; elongation = 9.85%) was obtained from methylcellulose-glucomannan-pectin at ratio 1:4:1, respectively. Then, gelatin was added to this polysaccharide blend and the pH was adjusted to 4, 5 and 6. Results showed significant improvement in WVP when films were made at pH 5 and at polysaccharides/gelatin ratio of 90/10 and 10/90, reaching 0.094 and 0.118 g.mm/h.m².kPa as values, respectively. Films with the best mechanical properties were obtained from the blend of polysaccharides, whereas WVP was improved from the blend of polysaccharides and gelatin at pH 5.
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The objective of this study was to obtain babassu coconut milk powder microencapsulated by spray drying process using gum Arabic as wall material. Coconut milk was extracted by babassu peeling, grinding (with two parts of water), and vacuum filtration. The milk was pasteurized at 85 ºC for 15 minutes and homogenized to break up the fat globules, rendering the milk a uniform consistency. A central composite rotatable design with a range of independent variables was used: inlet air temperature in the dryer (170-220 ºC) and gum Arabic concentration (10-20%, w/w) on the responses: moisture content (0.52-2.39%), hygroscopicity (6.98-9.86 g adsorbed water/100g solids), water activity (0.14-0.58), lipid oxidation (0.012-0.064 meq peroxide/kg oil), and process yield (20.33-30.19%). All variables influenced significantly the responses evaluated. Microencapsulation was optimized for maximum process yield and minimal lipid oxidation. The coconut milk powder obtained at optimum conditions was characterized in terms of morphology, particle size distribution, bulk and absolute density, porosity, and wettability.
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This study aimed at evaluating the effect of different concentrations of hydrolyzed collagen (HC) on the properties of an orally disintegrating film containing propolis ethanol extract (PEE) as an active component. The films were evaluated in terms of total phenols, mechanical properties, solubility, contact angle, disintegration time, and microstructure. The films were prepared by casting with 2 g of protein mass (gelatin and HC), 30 g of sorbitol/100 g of protein mass, and 100 g of PEE/100 g of protein mass. HC was incorporated at concentrations of 0, 10, 20, and 30 g/100 g of protein mass. It was found that increased concentrations of HC reduced tensile strength and increased elongation; however, all films showed plastic behavior. An increase in solubility at 25 ºC, a reduction in the contact angle, and disintegration time were also observed. Thus, higher concentrations of collagen led to more hydrophilic and more soluble polymeric matrices that showed shorter dissolution time, favoring the use of these materials as carriers for active compounds to be delivered in the oral cavity.
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The current thesis manuscript studies the suitability of a recent data assimilation method, the Variational Ensemble Kalman Filter (VEnKF), to real-life fluid dynamic problems in hydrology. VEnKF combines a variational formulation of the data assimilation problem based on minimizing an energy functional with an Ensemble Kalman filter approximation to the Hessian matrix that also serves as an approximation to the inverse of the error covariance matrix. One of the significant features of VEnKF is the very frequent re-sampling of the ensemble: resampling is done at every observation step. This unusual feature is further exacerbated by observation interpolation that is seen beneficial for numerical stability. In this case the ensemble is resampled every time step of the numerical model. VEnKF is implemented in several configurations to data from a real laboratory-scale dam break problem modelled with the shallow water equations. It is also tried in a two-layer Quasi- Geostrophic atmospheric flow problem. In both cases VEnKF proves to be an efficient and accurate data assimilation method that renders the analysis more realistic than the numerical model alone. It also proves to be robust against filter instability by its adaptive nature.
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Abstract Composite films of chitosan, fish gelatin and microbial transglutaminase (MTgase) were developed. Films were produced by the casting method and dried at room temperature for 30 h, conditioned for 7 days at 30 °C at a relative humidity (RH) from 11 to 90%, and characterized. Chitosan:fish gelatin films in different proportions (100:0, 75:25, 50:50) with MTgase, were subjected to tensile properties and water vapor transmission (WVT) testing. The results showed that tensile strength decreased with an increase in RH and with an increase in gelatin content. Percent of elongation also increased with increasing RH and gelatin concentration. Water vapor transmission showed an increase proportional to an increase in RH with the presence of gelatin being unfavorable for reducing WVT. Results in this work allowed studying the effect of relative humidity on tensile and water vapor properties of chitosan and fish gelatin films.
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Abstract The research work aimed at investigating the effect of pre-harvest gibberellic acid (GA3) treatment on the quality of ‘Obilnaja’ and ‘Black Star’ Japanese plum varieties. GA3 was sprayed onto the trees during the fruit color break at 0, 25, 50, 75, and 100 ppm concentrations. After pre-cooling, the plums were placed in modified atmosphere packages and exposed to the following conditions as follows: short storage-transportation (ST) [20 days at 2 °C and 90% relative humidity (RH)]; distribution center (DC) (5 days at 6 °C and 80% RH), and shelf life conditions (SL) (2 days at 20 °C and 70% RH). Pre-harvest GA3 treatments increased the fruit weight and size. Treatment of GA3 at 50, 75, and 100 ppm increased the fruit flesh firmness and total soluble substances (TSS) values in both the plum varieties during storage, transport, and marketing; it also limited the weight loss during the marketing process. Treatment of GA3 had no significant effects on the color, titratable acidity (TA), and the total phenolic and antioxidant activity values of plums. Pre-harvest GA3 treatment at 50 ppm GA3 can be thus recommended for both the plum varieties due to its effect on the fruit quality.
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The aim of this work was to calibrate the material properties including strength and strain values for different material zones of ultra-high strength steel (UHSS) welded joints under monotonic static loading. The UHSS is heat sensitive and softens by heat due to welding, the affected zone is heat affected zone (HAZ). In this regard, cylindrical specimens were cut out from welded joints of Strenx® 960 MC and Strenx® Tube 960 MH, were examined by tensile test. The hardness values of specimens’ cross section were measured. Using correlations between hardness and strength, initial material properties were obtained. The same size specimen with different zones of material same as real specimen were created and defined in finite element method (FEM) software with commercial brand Abaqus 6.14-1. The loading and boundary conditions were defined considering tensile test values. Using initial material properties made of hardness-strength correlations (true stress-strain values) as Abaqus main input, FEM is utilized to simulate the tensile test process. By comparing FEM Abaqus results with measured results of tensile test, initial material properties will be revised and reused as software input to be fully calibrated in such a way that FEM results and tensile test results deviate minimum. Two type of different S960 were used including 960 MC plates, and structural hollow section 960 MH X-joint. The joint is welded by BöhlerTM X96 filler material. In welded joints, typically the following zones appear: Weld (WEL), Heat affected zone (HAZ) coarse grained (HCG) and fine grained (HFG), annealed zone, and base material (BaM). Results showed that: The HAZ zone is softened due to heat input while welding. For all the specimens, the softened zone’s strength is decreased and makes it a weakest zone where fracture happens while loading. Stress concentration of a notched specimen can represent the properties of notched zone. The load-displacement diagram from FEM modeling matches with the experiments by the calibrated material properties by compromising two correlations of hardness and strength.
Resumo:
Tämän pro gradu -tutkielman tavoitteena oli ymmärtää ja kuvata korkeasti koulutettujen henkilöiden selviytymistä työn menetyksestä ja pitkittyneestä työttömyydestä. Tutkimuksessa tarkasteltiin pakotettua uramuutosta ja työttömyyttä sekä siitä selviytymistä yksilön kokemuksen näkökulmasta. Lisäksi tutkittiin työttömyyden tukipalveluiden hyödyllisyyttä. Tutkimus toteutettiin kvalitatiivisena kuvailevana tapaustutkimuksena. Tutkimuksen empiirinen aineisto kerättiin haastattelemalla 13 korkeasti koulutettua uusimaalaista työtöntä henkilöä. Haastattelut toteutettiin puolistrukturoitua teemahaastattelumenetelmää käyttäen. Tutkimuksen tulosten perusteella voidaan havaita, että työn menetyksellä koettiin olevan sekä negatiivisia että positiivisia vaikutuksia. Työn menetys koettiin osittain helpotuksena ja hengähdystaukona. Henkilöt selviytyivät itse työn menetyksen tilanteesta jokseenkin hyvin, etenkin jos muutokseen oli voinut varautua ja irtisanomisperusteet olivat selkeät. Korkeasti koulutetut henkilöt käyttivät monipuolisesti sekä tunne- että ongelmakeskeisiä selviytymisstrategioita selviytyäkseen työttömyydestä. Näistä aktiivinen työnhaku sekä opiskelu korostuivat selviytymiskeinoina. Työttömyyden pitkittyminen heikensi selvästi yksilön hyvinvointia ja vertaistuen merkitys korostui työttömyyden pitkittyessä. Tutkimuksesta ilmeni, että julkiset työvoimapalvelut eivät tue riittävästi korkeasti koulutettuja työttömiä. Tukipalveluja tulisi kehittää vastaamaan paremmin muuttuneiden työmarkkinoiden vaateita, sillä työmarkkinoiden muutokset haastavat urien uudenlaiseen tarkasteluun.
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Inside cyber security threats by system administrators are some of the main concerns of organizations about the security of systems. Since operating systems are controlled and managed by fully trusted administrators, they can negligently or intentionally break the information security and privacy of users and threaten the system integrity. In this thesis, we propose some solutions for enhancing the security of Linux OS by restricting administrators’ access to superuser’s privileges while they can still manage the system. We designed and implemented an interface for administrators in Linux OS called Linux Admins’ User Interface (LAUI) for managing the system in secure ways. LAUI along with other security programs in Linux like sudo protect confidentiality and integrity of users’ data and provide a more secure system against administrators’ mismanagement. In our model, we limit administrators to perform managing tasks in secure manners and also make administrators accountable for their acts. In this thesis we present some scenarios for compromising users’ data and breaking system integrity by system administrators in Linux OS. Then we evaluate how our solutions and methods can secure the system against these administrators’ mismanagement.
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Diplomityön tavoitteena on Rikosseuraamuslaitoksen tulosohjauksen kuvaaminen, mää-rittely, arviointi ja kehitysehdotusten tekeminen. Lisäksi määritellään normi- ja informaa-tio-ohjaus sekä tarkastellaan kuinka ne näkyvät tulosohjauksessa. Informaatio-ohjauksesta tuodaan esille keskeisimpiä kehityskohteita. Toiminnan tehostamistarpeet johtuvat yleisestä taloustilanteesta ja sitä seuraavasta määrärahojen pienenemisestä. Aluksi pidettiin puolistrukturoidut haastattelut, joiden perusteella kuvattiin laitoksen pro-sessikartta. Tämän jälkeen tulos- ja normiohjauksesta tehtiin eritasoisia prosessikuvauk-sia. Kuvauksilla rajattiin ja selvennettiin tarkasteltavia prosesseja. Kirjallisuuden, tutki-musten ja selvitysten avulla kartoitettiin tulosohjauksen yleisiä kehityskohteita. Niitä ver-rattiin haastattelutietoihin, arvioitiin tulosohjauksen nykytilaa ja tehtiin kehitysehdotuksia. Tulosohjauksesta löytyi useita kehityskohteita. Strategisen toimenpidesuunnitelman edis-tymiseen tulisi tehdä raportointiaikataulu. Tulostavoitteita voisi valmistella enemmän työntekijälähtöisesti ja yksiköille tulisi laatia omat strategiat. Asiakaspalautekyselyä tulisi kehittää, toteuttaa se verkkopohjaisena ja ottaa käyttöön kaikissa yksiköissä. Mittarit tuli-si liittää ydinprosesseihin ja jakaa ne laitos-alue-yksikkö -tasoille. Säännölliset raportit tulisi automatisoida ja antaa niiden tulostusoikeudet käyttäjille. Lisäksi kehittämishankkeita ja projekteja voisi hieman vähentää mutta viedä ne tehokkaammin läpi. Normi- ja informaatio-ohjaus ovat kiinteä osa tulosohjausta. Normiohjaus perustuu pääasiassa säädöksiin ja informaatio-ohjaus tiedolla ohjaamiseen. Informaatio-ohjauksessa tulisi kiinnittää huomiota aluekeskuksen tiedottamiseen, ettei yksiköitä ohjata keskushallinnosta aluekeskuksen ohi. Keskushallinnon tulisi myös päivittää ohjeistukset nopeammin erityisesti lakimuutosten yhteydessä. Myös vastuuta voisi jakaa enemmän alueille. Käyttöön voisi ottaa uuden tiedotuskanavan, esimerkiksi sähköinen uutislehtinen tai info-näytöt taukotiloissa.
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Viimeaikaisen talouden yleisen heikon tilanteen johdosta päättäjät ympäri Eurooppaa ovat kääntyneet pienten ja keskisuurten yritysten (pk-yritys) puoleen työllisyyden parantamiseksi. Pk-yritysten edustaessa yli 99% Suomen yrityskannasta, ovat ne erittäin tärkeässä asemassa työllisyystilanteen lisäksi myös maamme talouden kannalta, ja pk-yrityksille onkin asetettu kasvupaineita viimeaikaisten kasvuyritysten menestystarinoiden innoittamana. Tässä tutkimuksessa pääasiallisena tavoitteena on tutkia pk-yritysten kasvuun liittyviä tekijöitä kasvun mahdollistavien sekä kasvua rajoittavien tekijöiden kannalta. Pääasiallisen tavoitteen ohella on tutkittu myös pk-yritysten tekemiä konkreettisia toimia kasvua mahdollistavien tekijöiden vahvistamiseksi, sekä kasvua rajoittavien tekijöiden murtamiseksi. Tutkimus etenee siten, että ensin käydään läpi pk-yritysten kasvuun liittyviä yleisiä asioita, jonka jälkeen siirrytään kasvun mahdollistaviin ja sitä rajoittaviin tekijöihin. Tutkimus on toteutettu laadullisena tutkimuksena eli se on kvalitatiivinen tutkimus. Tutkimuksen empiirinen aineisto koostuu neljän pk-yrityksen teemahaastatteluista, sekä kyselylomakkeesta, joissa kartoitettiin pk-yritysten omistaja-johtajien mielipiteitä yritysten kasvun mahdollistavista ja sitä rajoittavista tekijöistä. Teemahaastattelujen haastattelurunko on rakennettu pk-yritysten kasvua käsittelevien artikkelien ja niissä ilmenneiden kasvuun liittyvien havaintojen pohjalta. Tutkimuksen perusteella pk-yritysten omistaja-johtajat ovat sitä mieltä, että Suomen veropoliittiset, sekä työlainsäädännölliset ratkaisut rajoittavat yritysten kasvua, eivätkä kannusta yrittäjyyteen. Tämän lisäksi kasvua rajoittavat omistaja-johtajien tavoitteet yritystoimintaan liittyen, sekä pätevän työvoiman rekrytointiin liittyvät ongelmat. Kasvun mahdollistavien tekijöiden osalta omistaja-johtajat pitivät tärkeinä yritystoimintaa tukevien järjestelmien merkitystä, yrityksen tunnetuksi tekemistä, yrityksen ja sen sidosryhmien välisten suhteiden kehittämistä ja yhteistyötä sekä yritystoiminnan laadun kehittämistä ja valvontaa. Tutkimuksessa ilmeni myös pk-yritysten pystyvän murtamaan aikaisemmissa tutkimuksissa ilmenneitä kasvua rajoittavia tekijöitä tehokkaasti, saavan aikaan kasvua niiden olemassaolosta huolimatta.