Towards conceptually comprehensive and integrated theory of entrepreneurial opportunity

Insufficient understanding of entrepreneurial opportunities characterizes entrepreneurship research (Companys & McMullen 2006, 302). Subsequently, the purpose of this study was to analyze the concept of entrepreneurial opportunity and to explore and synthetize the integrated theory of entrepreneurial opportunity. A theoretical and concept analytical approach was adapted. Findings of this study was that entrepreneurial opportunity concept was used for variety of different phenomena. No commonly accepted definition existed. Altogether 24 attributes that described the concept were found. The most frequently attached attributes were agent and action, new goods and services, market, value, new means ends or both, and future. Further, the results implied that opportunity could be best understood as a part of a process. Opportunity emerges out of intervened factors. Changes in the environment together with factors related to knowledge, cognition and social ties are the most important drivers of opportunity. Preventing factors that impeded the emergence of opportunity were typically related to cognitive and organizational factors. This study found a tendency towards more integrated theory of entrepreneurial opportunity. The integrated theory acknowledged the usefulness of both discovery and creation theories of opportunity in explaining opportunity. Yet three argument types of integrating two different opportunity theories were identified. These were process category, contextual category and complementing category. Opportunity is at the same time cognitive, social and linguistic construct, although it is shaped by the objective environment. Opportunity requires linguistic endeavors to become explicit. Materialization of opportunity occurs in a social context. Moreover, it is always characterized by some extent of subjectivity, as opportunities cannot appear without the agent and their action. Due to these the concept remains always to some extent ambiguous. Tolerating and harnessing change and investing in human and social capital create the preeminent environment for the entrepreneurial opportunity to be identified.

Re-usable ASIC integrationverification software architecture

Mikropiirien valmistus- ja suunnittelutekniikoiden kehittyminen mahdollistaa yhä monimutkaisempien mikropiirien valmistamisen. Piirien verifioinnista onkin tullut prosessin aikaa vievin osa,sillä kompleksisuuden kasvaessa kasvaa verifioinnin tarve eksponentiaalisesti. Vaikka erinäisiä strategioita piirien integroinnin verifiointiin on esitetty, mm. verifioinnin jakaminen koko suunnitteluprosessin ajalle, jopa yli puolet koko piirin suunnitteluun ja valmistukseen käytetystä työmäärästä kuluu verifiointiin. Uudelleenkäytettävät komponentit ovat pääosassa piirin suunnittelussa, mutta verifioinnissa uudelleenkäytettävyyttä ei ole otettu kunnolla käyttöön ainakaan verifiointiohjelmistojen osalta. Tämä diplomityö esittelee uudelleenkäytettävän mikropiirien verifiointiohjelmistoarkkitehtuurin, jolla saadaan verifiointitaakkaa vähennettyä poistamalla verifioinnissa käytettävien ohjelmistojen uudelleensuunnittelun ja toteuttamisen tarvetta.

FPGA-Based Control Design for Power Electronic Applications

Tehoelektoniikkalaitteella tarkoitetaan ohjaus- ja säätöjärjestelmää, jolla sähköä muokataan saatavilla olevasta muodosta haluttuun uuteen muotoon ja samalla hallitaan sähköisen tehon virtausta lähteestä käyttökohteeseen. Tämä siis eroaa signaalielektroniikasta, jossa sähköllä tyypillisesti siirretään tietoa hyödyntäen eri tiloja. Tehoelektroniikkalaitteita vertailtaessa katsotaan yleensä niiden luotettavuutta, kokoa, tehokkuutta, säätötarkkuutta ja tietysti hintaa. Tyypillisiä tehoelektroniikkalaitteita ovat taajuudenmuuttajat, UPS (Uninterruptible Power Supply) -laitteet, hitsauskoneet, induktiokuumentimet sekä erilaiset teholähteet. Perinteisesti näiden laitteiden ohjaus toteutetaan käyttäen mikroprosessoreja, ASIC- (Application Specific Integrated Circuit) tai IC (Intergrated Circuit) -piirejä sekä analogisia säätimiä. Tässä tutkimuksessa on analysoitu FPGA (Field Programmable Gate Array) -piirien soveltuvuutta tehoelektroniikan ohjaukseen. FPGA-piirien rakenne muodostuu erilaisista loogisista elementeistä ja niiden välisistä yhdysjohdoista.Loogiset elementit ovat porttipiirejä ja kiikkuja. Yhdysjohdot ja loogiset elementit ovat piirissä kiinteitä eikä koostumusta tai lukumäärää voi jälkikäteen muuttaa. Ohjelmoitavuus syntyy elementtien välisistä liitännöistä. Piirissä on lukuisia, jopa miljoonia kytkimiä, joiden asento voidaan asettaa. Siten piirin peruselementeistä voidaan muodostaa lukematon määrä erilaisia toiminnallisia kokonaisuuksia. FPGA-piirejä on pitkään käytetty kommunikointialan tuotteissa ja siksi niiden kehitys on viime vuosina ollut nopeaa. Samalla hinnat ovat pudonneet. Tästä johtuen FPGA-piiristä on tullut kiinnostava vaihtoehto myös tehoelektroniikkalaitteiden ohjaukseen. Väitöstyössä FPGA-piirien käytön soveltuvuutta on tutkittu käyttäen kahta vaativaa ja erilaista käytännön tehoelektroniikkalaitetta: taajuudenmuuttajaa ja hitsauskonetta. Molempiin testikohteisiin rakennettiin alan suomalaisten teollisuusyritysten kanssa soveltuvat prototyypit,joiden ohjauselektroniikka muutettiin FPGA-pohjaiseksi. Lisäksi kehitettiin tätä uutta tekniikkaa hyödyntävät uudentyyppiset ohjausmenetelmät. Prototyyppien toimivuutta verrattiin vastaaviin perinteisillä menetelmillä ohjattuihin kaupallisiin tuotteisiin ja havaittiin FPGA-piirien mahdollistaman rinnakkaisen laskennantuomat edut molempien tehoelektroniikkalaitteiden toimivuudessa. Työssä on myösesitetty uusia menetelmiä ja työkaluja FPGA-pohjaisen säätöjärjestelmän kehitykseen ja testaukseen. Esitetyillä menetelmillä tuotteiden kehitys saadaan mahdollisimman nopeaksi ja tehokkaaksi. Lisäksi työssä on kehitetty FPGA:n sisäinen ohjaus- ja kommunikointiväylärakenne, joka palvelee tehoelektroniikkalaitteiden ohjaussovelluksia. Uusi kommunikointirakenne edistää lisäksi jo tehtyjen osajärjestelmien uudelleen käytettävyyttä tulevissa sovelluksissa ja tuotesukupolvissa.

Combining Customer Requirements and Modularity in Complete Tap Water Solution

This thesis studies forming a complete solution concept for tap water systems in project business environment. The aim of the study is to find tools and means for the target company to determine the scope of their tap water solution offering and to research what kind of organizational capabilities and resources are needed to supply such system solutions. With the help of literature, the characteristics of systems selling and project business and thematics of systems integration and integrated solutions are examined, and the significance of modularity and customer requirements in the given operational environment is discussed. After this, a checklist tool for customer requirements management is developed for the tap water system along with a module allocation method. The study proposes that with the checklist and module allocation the technical specifications can be extensively and innovatively defined for the system. The tools developed are a part of a complete tap water solution concept, which suggests that integrated solutions might constitute possibilities for the company to outperform its competitors when the traditional business methods of the industry are becoming obsolete.

Exploring Adaptive Implementation of On-Chip Networks

As technology geometries have shrunk to the deep submicron regime, the communication delay and power consumption of global interconnections in high performance Multi- Processor Systems-on-Chip (MPSoCs) are becoming a major bottleneck. The Network-on- Chip (NoC) architecture paradigm, based on a modular packet-switched mechanism, can address many of the on-chip communication issues such as performance limitations of long interconnects and integration of large number of Processing Elements (PEs) on a chip. The choice of routing protocol and NoC structure can have a significant impact on performance and power consumption in on-chip networks. In addition, building a high performance, area and energy efficient on-chip network for multicore architectures requires a novel on-chip router allowing a larger network to be integrated on a single die with reduced power consumption. On top of that, network interfaces are employed to decouple computation resources from communication resources, to provide the synchronization between them, and to achieve backward compatibility with existing IP cores. Three adaptive routing algorithms are presented as a part of this thesis. The first presented routing protocol is a congestion-aware adaptive routing algorithm for 2D mesh NoCs which does not support multicast (one-to-many) traffic while the other two protocols are adaptive routing models supporting both unicast (one-to-one) and multicast traffic. A streamlined on-chip router architecture is also presented for avoiding congested areas in 2D mesh NoCs via employing efficient input and output selection. The output selection utilizes an adaptive routing algorithm based on the congestion condition of neighboring routers while the input selection allows packets to be serviced from each input port according to its congestion level. Moreover, in order to increase memory parallelism and bring compatibility with existing IP cores in network-based multiprocessor architectures, adaptive network interface architectures are presented to use multiple SDRAMs which can be accessed simultaneously. In addition, a smart memory controller is integrated in the adaptive network interface to improve the memory utilization and reduce both memory and network latencies. Three Dimensional Integrated Circuits (3D ICs) have been emerging as a viable candidate to achieve better performance and package density as compared to traditional 2D ICs. In addition, combining the benefits of 3D IC and NoC schemes provides a significant performance gain for 3D architectures. In recent years, inter-layer communication across multiple stacked layers (vertical channel) has attracted a lot of interest. In this thesis, a novel adaptive pipeline bus structure is proposed for inter-layer communication to improve the performance by reducing the delay and complexity of traditional bus arbitration. In addition, two mesh-based topologies for 3D architectures are also introduced to mitigate the inter-layer footprint and power dissipation on each layer with a small performance penalty.

Thinking Outside the Box: Enhancing Science Teaching by Combining (Instead of Contrasting) Laboratory and Simulation Activities

The focus of the present work was on 10- to 12-year-old elementary school students’ conceptual learning outcomes in science in two specific inquiry-learning environments, laboratory and simulation. The main aim was to examine if it would be more beneficial to combine than contrast simulation and laboratory activities in science teaching. It was argued that the status quo where laboratories and simulations are seen as alternative or competing methods in science teaching is hardly an optimal solution to promote students’ learning and understanding in various science domains. It was hypothesized that it would make more sense and be more productive to combine laboratories and simulations. Several explanations and examples were provided to back up the hypothesis. In order to test whether learning with the combination of laboratory and simulation activities can result in better conceptual understanding in science than learning with laboratory or simulation activities alone, two experiments were conducted in the domain of electricity. In these experiments students constructed and studied electrical circuits in three different learning environments: laboratory (real circuits), simulation (virtual circuits), and simulation-laboratory combination (real and virtual circuits were used simultaneously). In order to measure and compare how these environments affected students’ conceptual understanding of circuits, a subject knowledge assessment questionnaire was administered before and after the experimentation. The results of the experiments were presented in four empirical studies. Three of the studies focused on learning outcomes between the conditions and one on learning processes. Study I analyzed learning outcomes from experiment I. The aim of the study was to investigate if it would be more beneficial to combine simulation and laboratory activities than to use them separately in teaching the concepts of simple electricity. Matched-trios were created based on the pre-test results of 66 elementary school students and divided randomly into a laboratory (real circuits), simulation (virtual circuits) and simulation-laboratory combination (real and virtual circuits simultaneously) conditions. In each condition students had 90 minutes to construct and study various circuits. The results showed that studying electrical circuits in the simulation–laboratory combination environment improved students’ conceptual understanding more than studying circuits in simulation and laboratory environments alone. Although there were no statistical differences between simulation and laboratory environments, the learning effect was more pronounced in the simulation condition where the students made clear progress during the intervention, whereas in the laboratory condition students’ conceptual understanding remained at an elementary level after the intervention. Study II analyzed learning outcomes from experiment II. The aim of the study was to investigate if and how learning outcomes in simulation and simulation-laboratory combination environments are mediated by implicit (only procedural guidance) and explicit (more structure and guidance for the discovery process) instruction in the context of simple DC circuits. Matched-quartets were created based on the pre-test results of 50 elementary school students and divided randomly into a simulation implicit (SI), simulation explicit (SE), combination implicit (CI) and combination explicit (CE) conditions. The results showed that when the students were working with the simulation alone, they were able to gain significantly greater amount of subject knowledge when they received metacognitive support (explicit instruction; SE) for the discovery process than when they received only procedural guidance (implicit instruction: SI). However, this additional scaffolding was not enough to reach the level of the students in the combination environment (CI and CE). A surprising finding in Study II was that instructional support had a different effect in the combination environment than in the simulation environment. In the combination environment explicit instruction (CE) did not seem to elicit much additional gain for students’ understanding of electric circuits compared to implicit instruction (CI). Instead, explicit instruction slowed down the inquiry process substantially in the combination environment. Study III analyzed from video data learning processes of those 50 students that participated in experiment II (cf. Study II above). The focus was on three specific learning processes: cognitive conflicts, self-explanations, and analogical encodings. The aim of the study was to find out possible explanations for the success of the combination condition in Experiments I and II. The video data provided clear evidence about the benefits of studying with the real and virtual circuits simultaneously (the combination conditions). Mostly the representations complemented each other, that is, one representation helped students to interpret and understand the outcomes they received from the other representation. However, there were also instances in which analogical encoding took place, that is, situations in which the slightly discrepant results between the representations ‘forced’ students to focus on those features that could be generalised across the two representations. No statistical differences were found in the amount of experienced cognitive conflicts and self-explanations between simulation and combination conditions, though in self-explanations there was a nascent trend in favour of the combination. There was also a clear tendency suggesting that explicit guidance increased the amount of self-explanations. Overall, the amount of cognitive conflicts and self-explanations was very low. The aim of the Study IV was twofold: the main aim was to provide an aggregated overview of the learning outcomes of experiments I and II; the secondary aim was to explore the relationship between the learning environments and students’ prior domain knowledge (low and high) in the experiments. Aggregated results of experiments I & II showed that on average, 91% of the students in the combination environment scored above the average of the laboratory environment, and 76% of them scored also above the average of the simulation environment. Seventy percent of the students in the simulation environment scored above the average of the laboratory environment. The results further showed that overall students seemed to benefit from combining simulations and laboratories regardless of their level of prior knowledge, that is, students with either low or high prior knowledge who studied circuits in the combination environment outperformed their counterparts who studied in the laboratory or simulation environment alone. The effect seemed to be slightly bigger among the students with low prior knowledge. However, more detailed inspection of the results showed that there were considerable differences between the experiments regarding how students with low and high prior knowledge benefitted from the combination: in Experiment I, especially students with low prior knowledge benefitted from the combination as compared to those students that used only the simulation, whereas in Experiment II, only students with high prior knowledge seemed to benefit from the combination relative to the simulation group. Regarding the differences between simulation and laboratory groups, the benefits of using a simulation seemed to be slightly higher among students with high prior knowledge. The results of the four empirical studies support the hypothesis concerning the benefits of using simulation along with laboratory activities to promote students’ conceptual understanding of electricity. It can be concluded that when teaching students about electricity, the students can gain better understanding when they have an opportunity to use the simulation and the real circuits in parallel than if they have only the real circuits or only a computer simulation available, even when the use of the simulation is supported with the explicit instruction. The outcomes of the empirical studies can be considered as the first unambiguous evidence on the (additional) benefits of combining laboratory and simulation activities in science education as compared to learning with laboratories and simulations alone.

Private Home Care in Municipal Service Systems – A Case Study among Finnish and Swedish Municipalities

The aim of this study is to assess the current and future preconditions for conducting private business in municipal service systems for home care in Lahti and Hyvinkää in Finland, and in Uppsala and Huddinge in Sweden. This study also aims to assess the implications of quality related issues on the preconditions for conducting private business in the service systems in question. The theories and the research methodologies of the study are based on the Business Model Generation and the Business Model Canvas -concepts. Also a couple of frameworks on implications of quality are applied and integrated into the study. The study is completed as a case study – with structured and identical approaches for all four municipalities. The analyses and assessments of the study are primarily qualitative, but supported by simple quantitative methodologies. The data of the study consists primarily of publicly available information, and secondarily of answers provided by the case-municipalities to multiple choice questions. The results of the study show that the service systems for home care among the case-municipalities are, from perspective of private companies, diverse with local characteristics. Both the premises for conducting private business and the quality-issues are in many respects different in the Finnish and the Swedish case-municipalities. This is partly due to differences in the national service systems; the service voucher system versus the system of choice. Still, it appears that the current preconditions for conducting private business in the service systems for home care, including the implications of quality, would be more favorable in Uppsala and Huddinge than in Lahti and Hyvinkää. On the other hand, the service systems are subject to changes, and the most positive and significant development is here forecasted for a Finnish case-municipality (Lahti). Communication of quality is clearly more advanced in the Swedish case-municipalities. The results of this study can be utilized in several ways, for instance by private companies interested in entering into service systems for home care, either in some of the case-municipalities, or in some other Finnish or Swedish municipalities. Also municipalities can apply the analyses of the study when designing, developing or evaluating their own service systems for home care.

Establishment of a health and safety management system according to the OHSAS 18001 standard

The thesis develops guidelines for the implementation of the health and safety management system according to the OHSAS 18001 standard, as well as the feasible threat analysis, project proposal schedule, future system quality improvements and organizational change evaluation. The theoretical part clarifies determination of occupational health and safety, its management system, the OHSAS 18001 standard and integrated management system compounded of triple ISO 14001, ISO 9001 and OHSAS 18001 standards. The literature includes such important aspects as human factor, organizational policies, possible benefits, threats, organizational safety culture, Deming’s quality improvement cycle, system implementation, maintenance and cost matters. The empirical part demonstrates real-life situation by using Andritz Pulp & Paper Oy as a case study. Prior the thesis proposal, Andritz Group is analysed including separate business areas, acquisition and integration strategies, current status of the health and safety management and parallel experiences of the largest business area Andritz Hydro. The proposal is aimed at improving the current health and safety system for the permanent and sub-contracted employees at Andritz Pulp & Paper both in Finland and in various projects globally.

Qualitative Characteristics and Quantitative Measures of Solution's Reliability in Discrete Optimization: Traditional Analytical Approaches, Innovative Computational Methods and Applicability

The purpose of this thesis is twofold. The first and major part is devoted to sensitivity analysis of various discrete optimization problems while the second part addresses methods applied for calculating measures of solution stability and solving multicriteria discrete optimization problems. Despite numerous approaches to stability analysis of discrete optimization problems two major directions can be single out: quantitative and qualitative. Qualitative sensitivity analysis is conducted for multicriteria discrete optimization problems with minisum, minimax and minimin partial criteria. The main results obtained here are necessary and sufficient conditions for different stability types of optimal solutions (or a set of optimal solutions) of the considered problems. Within the framework of quantitative direction various measures of solution stability are investigated. A formula for a quantitative characteristic called stability radius is obtained for the generalized equilibrium situation invariant to changes of game parameters in the case of the H¨older metric. Quality of the problem solution can also be described in terms of robustness analysis. In this work the concepts of accuracy and robustness tolerances are presented for a strategic game with a finite number of players where initial coefficients (costs) of linear payoff functions are subject to perturbations. Investigation of stability radius also aims to devise methods for its calculation. A new metaheuristic approach is derived for calculation of stability radius of an optimal solution to the shortest path problem. The main advantage of the developed method is that it can be potentially applicable for calculating stability radii of NP-hard problems. The last chapter of the thesis focuses on deriving innovative methods based on interactive optimization approach for solving multicriteria combinatorial optimization problems. The key idea of the proposed approach is to utilize a parameterized achievement scalarizing function for solution calculation and to direct interactive procedure by changing weighting coefficients of this function. In order to illustrate the introduced ideas a decision making process is simulated for three objective median location problem. The concepts, models, and ideas collected and analyzed in this thesis create a good and relevant grounds for developing more complicated and integrated models of postoptimal analysis and solving the most computationally challenging problems related to it.

Theses and Dissertations Digital Library: Ten years of Open Access and Open Archives in Brazil

Poster at Open Repositories 2014, Helsinki, Finland, June 9-13, 2014

Advanced analysis and design methods for preparative chromatographic separation processes

Preparative liquid chromatography is one of the most selective separation techniques in the fine chemical, pharmaceutical, and food industries. Several process concepts have been developed and applied for improving the performance of classical batch chromatography. The most powerful approaches include various single-column recycling schemes, counter-current and cross-current multi-column setups, and hybrid processes where chromatography is coupled with other unit operations such as crystallization, chemical reactor, and/or solvent removal unit. To fully utilize the potential of stand-alone and integrated chromatographic processes, efficient methods for selecting the best process alternative as well as optimal operating conditions are needed. In this thesis, a unified method is developed for analysis and design of the following singlecolumn fixed bed processes and corresponding cross-current schemes: (1) batch chromatography, (2) batch chromatography with an integrated solvent removal unit, (3) mixed-recycle steady state recycling chromatography (SSR), and (4) mixed-recycle steady state recycling chromatography with solvent removal from fresh feed, recycle fraction, or column feed (SSR–SR). The method is based on the equilibrium theory of chromatography with an assumption of negligible mass transfer resistance and axial dispersion. The design criteria are given in general, dimensionless form that is formally analogous to that applied widely in the so called triangle theory of counter-current multi-column chromatography. Analytical design equations are derived for binary systems that follow competitive Langmuir adsorption isotherm model. For this purpose, the existing analytic solution of the ideal model of chromatography for binary Langmuir mixtures is completed by deriving missing explicit equations for the height and location of the pure first component shock in the case of a small feed pulse. It is thus shown that the entire chromatographic cycle at the column outlet can be expressed in closed-form. The developed design method allows predicting the feasible range of operating parameters that lead to desired product purities. It can be applied for the calculation of first estimates of optimal operating conditions, the analysis of process robustness, and the early-stage evaluation of different process alternatives. The design method is utilized to analyse the possibility to enhance the performance of conventional SSR chromatography by integrating it with a solvent removal unit. It is shown that the amount of fresh feed processed during a chromatographic cycle and thus the productivity of SSR process can be improved by removing solvent. The maximum solvent removal capacity depends on the location of the solvent removal unit and the physical solvent removal constraints, such as solubility, viscosity, and/or osmotic pressure limits. Usually, the most flexible option is to remove solvent from the column feed. Applicability of the equilibrium design for real, non-ideal separation problems is evaluated by means of numerical simulations. Due to assumption of infinite column efficiency, the developed design method is most applicable for high performance systems where thermodynamic effects are predominant, while significant deviations are observed under highly non-ideal conditions. The findings based on the equilibrium theory are applied to develop a shortcut approach for the design of chromatographic separation processes under strongly non-ideal conditions with significant dispersive effects. The method is based on a simple procedure applied to a single conventional chromatogram. Applicability of the approach for the design of batch and counter-current simulated moving bed processes is evaluated with case studies. It is shown that the shortcut approach works the better the higher the column efficiency and the lower the purity constraints are.

Issues in the Transatlantic Trade and Investment Partnership: A critical discourse analysis

Negotiating trade agreements is an important part of government trade policies, economic planning and part of the globally operating trading system of today. European Union and the United States have been active in the formation of trade agreements in global comparison. Now these two economic giants are engaged in negotiations to form their own trade agreement, the so called Transnational Trade and Investment Partnership (TTIP). The purpose of this thesis is to understand the reasons for making a trade agreement between two economic areas and understanding the issues it may include in the case of the TTIP. The TTIP has received a great deal of attention in the media. The opinions towards the partnership have been extreme, and the debate has been heated. The purpose of this study is to introduce the nature of the public discussion regarding the TTIP from Spring 2013 until 2014. The research problem is to find out what are the main issues in the agreement and what are the values influencing them. The study was conducted applying methods of critical discourse analysis to the chosen data. This includes gathering the issues from the data based on the attention each has received in the discussion. The underlying motives for raising different issues were analysed by investigating the authors’ position in the political, economic and social circuits. The perceived economic impacts of the TTIP are also under analysis with the same criteria. Some of the most respected economic newspapers globally were included in the research material as well as papers or reports published by the EU and global organisations. The analysis indicates a clear dichotomy of the attitudes towards the TTIP. Key problems include lack of transparency in the negotiations, the misunderstood investor-state dispute settlement, the constantly expanding regulatory issues and the risk of protectionism. The theory and data does suggest that the removal of tariffs is an effective tool for reaching economic gains in the TTIP and even more effective would be the reducing of non-tariff barriers, such as protectionism. Critics are worried over the rising influence of corporations over governments. The discourse analysis reveals that the supporters of the TTIP have values related to increasing welfare through economic growth. Critics do not deny the economic benefits but raise the question of inequality as a consequence. Overall they represent softer values such as sustainable development and democracy as a counter-attack to the corporate values of efficiency and the maximising of profits.

Analogisen tunnisteanalyysin käyttö korjauspalveluissa mikropiirien ylijännitteestä aiheutuneiden vaurioiden paikantamisen

Korjauspalveluissa aikaa vieviä tapauksia ovat mikropiirien vaikeasti paikannettavat viat. Tällaista vianetsintää varten yrityksemme oli ostanut Polar Fault Locator 780 –mittalaitteen, jolla voidaan mitata mikropiirien toimintaa käyttämällä analogista tunnisteanalyysiä. Diplomityön tavoitteena oli selvittää, miten mittaustapaa voidaan käyttää korjauspalveluissa. Tutkintaa lähestyttiin joidenkin tyypillisten komponenttien näkökulmasta, mutta pääpaino oli mikropiireissä. Joitain mikropiirejä vaurioitettiin tahallisesti, jolloin mittaustulokset uusittiin ja tutkittiin miten vaurioituminen näkyy mittaustuloksissa. Tutkimusmenetelmänä oli kirjallisuus ja empiirinen kokeellisuus. Diplomityön tuloksena oli, että tätä mittaustapaa käyttämällä mikropiirien kuntoa voidaan tutkia. Ongelmiksi osoittautuivat alkuperäinen oletus mittalaitteen tuloksien tulkinnasta ja taustamateriaalin heikko saatavuus. Täten mittalaite parhaiten soveltuu tilanteisiin, joissa sen antamia tuloksia verrataan suoraan toisen toimivaksi tunnetun yksikön mittaustuloksiin. Vaurioitettaessa komponenteissa oli kuitenkin havaittavissa selvä poikkeavuus.

Flexible Sensor for Wearable Vital Sign Monitoring System

In modern society, the body health is a very important issue to everyone. With the development of the science and technology, the new and developed body health monitoring device and technology will play the key role in the daily medical activities. This paper focus on making progress in the design of the wearable vital sign system. A vital sign monitoring system has been proposed and designed. The whole detection system is composed of signal collecting subsystem, signal processing subsystem, short-range wireless communication subsystem and user interface subsystem. The signal collecting subsystem is composed of light source and photo diode, after emiting light of two different wavelength, the photo diode collects the light signal reflected by human body tissue. The signal processing subsystem is based on the analog front end AFE4490 and peripheral circuits, the collected analog signal would be filtered and converted into digital signal in this stage. After a series of processing, the signal would be transmitted to the short-range wireless communication subsystem through SPI, this subsystem is mainly based on Bluetooth 4.0 protocol and ultra-low power System on Chip(SoC) nRF51822. Finally, the signal would be transmitted to the user end. After proposing and building the system, this paper focus on the research of the key component in the system, that is, the photo detector. Based on the study of the perovskite materials, a low temperature processed photo detector has been proposed, designed and researched. The device is made up of light absorbing layer, electron transporting and hole blocking layer, hole transporting and electron blocking layer, conductive substrate layer and metal electrode layer. The light absorbing layer is the important part of whole device, and it is fabricated by perovskite materials. After accepting the light, the electron-hole pair would be produced in this layer, and due to the energy level difference, the electron and hole produced would be transmitted to metal electrode and conductive substrate electrode through electron transporting layer and hole transporting layer respectively. In this way the response current would be produced. Based on this structure, the specific fabrication procedure including substrate cleaning; PEDOT:PSS layer preparation; pervoskite layer preparation; PCBM layer preparation; C60, BCP, and Ag electrode layer preparation. After the device fabrication, a series of morphological characterization and performance testing has been done. The testing procedure including film-forming quality inspection, response current and light wavelength analysis, linearity and response time and other optical and electrical properties testing. The testing result shows that the membrane has been fabricated uniformly; the device can produce obvious response current to the incident light with the wavelength from 350nm to 800nm, and the response current could be changed along with the light wavelength. When the light wavelength keeps constant, there exists a good linear relationship between the intensity of the response current and the power of the incident light, based on which the device could be used as the photo detector to collect the light information. During the changing period of the light signal, the response time of the device is several microseconds, which is acceptable working as a photo detector in our system. The testing results show that the device has good electronic and optical properties, and the fabrication procedure is also repeatable, the properties of the devices has good uniformity, which illustrates the fabrication method and procedure could be used to build the photo detector in our wearable system. Based on a series of testing results, the paper has drawn the conclusion that the photo detector fabricated could be integrated on the flexible substrate and is also suitable for the monitoring system proposed, thus made some progress on the research of the wearable monitoring system and device. Finally, some future prospect in system design aspect and device design and fabrication aspect are proposed.