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  • Rautio, Sanna (2022)
    Social and urban scholars have long been concerned with questions of how unknown others encounter and relate to one another in the city. Stranger encounters can happen spontaneously and serendipitously, for example, at bus stops, in trains or on park benches, often viewed as “chance” encounters. Other stranger encounters are carefully planned, for example, by using digital technology including online social networks, websites, and digital platforms. Today, digital platforms are reshaping the way we relate with strangers, yet there is little research on how stranger encounters are reconfigured by practices mediated through digital platforms. Against this background, the thesis attempts to address this research gap: stranger encounters mediated by two location-based digital platforms for social networking in Helsinki. The thesis focuses on two Finnish digital platforms for social networking, Nappi Naapuri and Commu, which are based around neighbourhood and community interactions. Both platforms lower the threshold of communication between strangers which have the potential to help eliminate loneliness, stress, and promote a sense of community. The thesis analyses planned encounters when meeting with other platform users to better understand what types of stranger encounters are emerging from digital platforms. Rather than focusing on the figure of the stranger as ‘other,’ the thesis examines digitally mediated practices whereby stranger encounters are valued and actively pursued by platform users. Through fieldwork encounters with strangers in Helsinki, the thesis analyses six stranger encounter vignettes to argue that by practicing an open and generous attitude towards unknown others can allow for moments of sociable curiosity, escapism, and intimacy to emerge between strangers. Using multiple methodologies including, autoethnography, walking with participants, participant observation and interviews, the thesis aims to better understand the role digital platforms can play in increasing stranger encounters in the city and how they have the potential to bring different people together to learn from one another and work on manners of cohabitation.
  • Suomalainen, Janne (2016)
    Waring's problem is one of the two classical problems in additive number theory, the other being Goldbach's conjecture. The aims of this thesis are to provide an elementary, purely arithmetic solution of the Waring problem, to survey its vast history and to outline a few variations to it. Additive number theory studies the patterns and properties, which arise when integers or sets of integers are added. The theory saw a new surge after 1770, just before Lagrange's celebrated proof of the four-square theorem, when a British mathematician, Lucasian professor Edward Waring made the profound statement nowadays dubbed as Waring's problem: for all integers n greater than one, there exists a finite integer s such that every positive integer is the sum of s nth powers of non-negative integers. Ever since, the problem has been taken up by many mathematicians and state of the art techniques have been developed - to the point that Waring's problem, in a general sense, can be considered almost completely solved. The first section of the thesis works as an introduction to the problem. We give a profile of Edward Waring, state the problem both in its original form and using present-day language, and take a broad look over the history of the problem. The main emphasis is on the classical version of the problem, whereas the modern version is described in Section 5 with numerous other variations. In addition, generalizations to integer-valued polynomials and to general algebraic fields are described. Goldbach's conjecture is also briefly illustrated. The elementary solution of Waring's problem is presented in Sections 2 to 4. Historical perspective is carried through the thesis with the profiles of the key mathematicians to the solution. The proof presented is an improved and simplified version of Yuri Linnik's solution of Waring's problem. The second section provides the groundwork, an ingenious density argument by Lev Shnirelman, which is applied to the problem in the so called Fundamental lemma presented in Section 3. The proofs of the intermediate results needed to prove the lemma are presented in the following sections. The third section reduces the proof to an estimation of the number of solutions of a certain system of Diophantine equations. The final argument, longish induction is given at the end of the fourth section. Even though Waring's problem is solved, the progress made in the field is far from being idle. The plethora of variations and generalizations, especially Ideal Waring's problem, Modern Waring's problem and Waring–Goldbach problem are actively studied today. It is surprising how deep a problem with such a seemingly simple assertion can be. Conclusively, the challenge in this branch of mathematics is to develop new mathematical methods to prove and explain what seems so obvious.
  • Juurinen, Iina (Helsingin yliopistoHelsingfors universitetUniversity of Helsinki, 2009)
    Water-ethanol mixtures are commonly used in industry and house holds. However, quite surprisingly their molecular-level structure is still not completely understood. In particular, there is evidence that the local intermolecular geometries depend significantly on the concentration. The aim of this study was to gain information on the molecular-level structures of water-ethanol mixtures by two computational methods. The methods are classical molecular dynamics (MD), where the movement of molecules can be studied, and x-ray Compton scattering, in which the scattering cross section is sensitive to the electron momentum density. Firstly, the water-ethanol mixtures were studied with MD simulations, with the mixture concentration ranging from 0 to 100%. For the simulations well-established force fields were used for the water and ethanol molecules (TIP4P and OPLS-AA, respectively). Moreover, two models were used for ethanol, rigid and non-rigid. In the rigid model the intramolecular bond lengths are fixed, whereas in the non-rigid model the lengths are determined by harmonic potentials. Secondly, mixtures with three different concentrations employing both ethanol models were studied by calculating the experimentally observable x-ray quantity, the Compton profile. In the MD simulations a slight underestimation in the density was observed as compared to experiment. Furthermore, a positive excess of hydrogen bonding with water molecules and a negative one with ethanol was quantified. Also, the mixture was found more structured when the ethanol concentration was higher. Negligible differences in the results were found between the two ethanol models. In contrast, in the Compton scattering results a notable difference between the ethanol models was observed. For the rigid model the Compton profiles were similar for all the concentrations, but for the non-rigid model they were distinct. This leads to two possibilities of how the mixing occurs. Either the mixing is similar in all concentrations (as suggested by the rigid model) or the mixing changes for different concentrations (as suggested by the non-rigid model). Either way, this study shows that the choice of the force field is essential in the microscopic structure formation in the MD simulations. When the sources of uncertainty in the calculated Compton profiles were analyzed, it was found that more statistics needs to be collected to reduce the statistical uncertainty in the final results. The obtained Compton scattering results can be considered somewhat preliminary, but clearly indicative of the behaviour of the water-ethanol mixtures when the force field is modified. The next step is to collect more statistics and compare the results with experimental data to decide which ethanol model describes the mixture better. This way, valuable information on the microscopic structure of water-ethanol mixtures can be found. In addition, information on the force fields in the MD simulations and on the ability of the MD simulations to reproduce the microscopic structure of binary liquids is obtained.
  • Muukkonen, Satu (Helsingin yliopistoHelsingfors universitetUniversity of Helsinki, 2007)
    In Cambodia, water has a special purpose as a source of life and livelihoods. Along with agriculture, fishing and forest use, industry, hydropower, navigation and tourism compete for the water resources. When rights and responsibilities related to essential and movable water are unclear, conflicts emerge easily. Therefore, water management is needed in order to plan and control the use of water resources. The international context is characterized by the Mekong River that flows through six countries. All of the countries by the river have very different roles and interests already depending on their geographical location. At the same time, water is also a tool for cooperation and peace. Locally, the water resources and related livelihoods create base for well-being, for economical and human resources in particular. They in turn are essential for the local people to participate and defend their rights to water use. They also help to construct the resource base of the state administration. Cambodia is highly dependent on the Mekong River. However, Cambodia has a volatile history whose effects can be seen for example in population structure, once suspended public institutions and weakened trust in the society. Relatively stable conditions came to the country as late as in the 1990s, therefore Cambodia for example has a weak status within the Mekong countries. This Master s thesis forms international, national and local interest groups of water use and analyzes their power relations and resources to affect water management. The state is seen as the salient actor as it has the formal responsibility of the water resources and of the coordination between the actions of different levels. In terms of water use this study focuses on production, in management on planning and in power relations on the resources. Water resources of Cambodia are seen consisting of the Mekong River and Tonle Sap Lake and the time span of the study is between the years 1991 and 2006. The material consists of semi-structured interviews collected during summer 2006 in Finland and in Cambodia as well as of literature and earlier studies. The results of the study show that the central state has difficulties to coordinate the actions of different actors because of its resource deficit and internal conflicts. The lessons of history and the vested interests of the actors of the state make it difficult to plan and to strengthen legislation. It seems that the most needed resources at the central state level are intangible as at the village level instead, the tangible resources (fulfilling the basic needs) are primarily important. The local decision-making bodies, NGOs and private sector mainly require legislation and legitimacy to support their role. However, the civil society and the international supporters are active and there are possibilities for new cooperation networks.
  • Murakami, Margaret (2023)
    Antarctic Bottom Water (AABW), a water mass that sinks to form the deepest limb of the meridional overturning circulation (MOC), is a key control on the ventilation of the Southern Ocean as well as global exchanges of heat, freshwater, and carbon. Sources of this water mass include latent heat polynyas found in Prydz Bay, East Antarctica, which expose the Southern Ocean to the colder atmosphere and are important sources of high salinity shelf water (HSSW). This water mass is the precursor to Dense Shelf Water (DSW) which can be exported from the continental shelf to form Antarctic Bottom Water (AABW). In this study, Lagrangian particle tracking of water masses within Prydz Bay was used to investigate the roles of seasonality, bathymetry, and the presence of other water masses on the mechanisms of water mass transformation (WMT), a series of key processes in the MOC. Online particles were released weekly within the Prydz Bay polynya region in a 10 km resolution simulation of the Whole Antarctic Ocean Model (WAOM10) and their forward trajectories were tracked for one year. Results highlight the export of Prydz Bay water along the westward Antarctic Slope Current (ASC). Cluster analysis of the results shows a winter signal for bottom water forming particles. When advected beneath the ice shelf, polynya water can mix with fresh meltwater, becoming less dense and forming ice shelf water (ISW). After this polynya-originating water departs the ice shelf again, its increased buoyancy can make future AABW formation less likely. This study confirms that the presence of modified circumpolar deep water (mCDW) can play a controlling factor in rates of DSW export as bottom water. Results show export of DSW from the Prydz Channel and Cape Darnley, mixing either along or across isopycnals depending on the influence of other water masses and cross-slope flow. Interactions with the ASC and major topographic features including the Enderby Land projection and several underwater canyons appear to influence the export of water to the deep ocean. WAOM10 finds realistic ratios of AABW formation as compared with observational data and shows greater low-density water formation than other models.
  • Nurminen, Tiina (2013)
    Hannukainen is an old mining area, at commune of Kolari in western Finnish Lapland. Rautaruukki Oy and Outokumpu Oy mined iron, copper and cold from the area in 1978 - 1990. Area is located in the Pajala-Kolari shear zone. Kaunisvaara mining project at Sweden is related to the same shear zone. Northland Mines Finland Oy is planning to restart mining of IOCG-type ore at Hannukainen area within the next couple of years. Quaternary deposits or water resources in Hannukainen area has not been examined in detail before. The mine development site is surrounded be three rivers, Valkeajoki in east, Kuerjoki in west and Äkäsjoki in south. The stratigraphical and hydrostratigraphical field studies in Hannukainen area were made in summer 2011. Stratigraphy of the Quaternary deposits was observed from the sections of Laurinoja open pit and from test pits dug to the area. Permeability of the sediment units were measured by using ring infiltration tests and calculated from grain size evaluations made from sediment samples. Groundwater was observed by evaluating the quality and representativeness of the groundwater monitoring wells, groundwater level measurements and also laboratory analyzes of main ions, trace-elements and isotope ratios of oxygen and hydrogen. In addition to chemistry samples, electric conductivity, pH, temperature and ratio of oxygen was measured with YSI multielectrode probe from rivers and open pit ponds. Groundwater - surface water interactions were observed by taking chemistry samples, measuring river bed temperatures and by installing minipiezometers. Quaternary deposits are mostly glaciofluvial and fluvial sands and gravels instead of tills. Sorted sandy sediments related to the braided river bars formed by Muonio Ice lake spillways are found from the present valleys of River Äkäsjoki, Valkeajoki and Kuerjoki. Sand and gravel sediments have good permeability and they host considerable amounts of water. Fine sediment units are thin and as discontinuous layers they host perched groundwater and confined groundwater. From the observed 23 groundwater monitoring wells only three represented the whole saturated aquifer and altogether six were other vice usable. The most remarkable problems were the lack of installation information and shortness of monitoring wells compared to the thick quaternary deposits in the area. Acid Mine Drainage -effect (AMD) of the old open pits, waste rock area and ore deposit itself could be detected from the groundwater monitoring wells in the old mining area and from the groundwater discharging to the river Äkäsjoki. Isotope ratios, river bed temperatures and hydraulic head difference in mini- piezometers reveal that groundwater is discharging from the mine development site to the rivers surrounding it. Hannukainen area is a challenging environment for mine siting. Hydrostratigraphy in the area is complicated, permeability of the Quaternary deposits is generally good, aquifer is multileveled and rivers surrounding the area get a significant amount of their water from groundwater forming in the mine development site. Most of the present groundwater monitoring wells are unusable, and in order to monitor the groundwater reliably some new monitoring wells should be installed. Major flow direction of surface and groundwater are from the mine development site to the rivers surrounding it. Classified groundwater areas should be outlined again, because present linings do not relate to true aquifers. Location of tailings area planned to the mine development site has been reconsidered.
  • Korkiakoski, Mika (2014)
    Cavity ring-down spectroscopy is a laser absorption technique based on the principle of measuring the rate of exponential decay of light intensity inside the ring-down cavity. When the absorption spectrum of a gas is known, it is possible to determine the mole fraction of this gas by measuring the height of the absorption peak, which can be acquired from the rate of decay of light. This technique is used in G1301, G2301 and G2401 (Picarro Inc.) gas analyzers which measure carbon dioxide (CO2), methane (CH4) and water vapor. However, measured gas mole fractions are diluted from their actual value; mostly due to variations in atmospheric water vapor. This effect causes large errors and it has to be corrected either by drying the sample or applying a water vapor correction. A default water vapor correction is included in Picarro gas analyzers, but it might not be accurate enough for use in some measurements. In this study, determination of water vapor correction coefficients was carried out by doing several droplet tests for seven different gas analyzers, which included one G2401, two G1301, four G2301gas analyzers. Mean correction functions determined for the analyzers were compared to the Picarro default correction. In addition, the comparison was made with time series data for one of the analyzers. Also, the water vapor measurement of the gas analyzers was calibrated to acquire the actual water vapor mole fraction. As a result, the factory correction for CO2 was proved sufficient for high accuracy measurements only up to 0.7 % water vapor mole fraction. For CH4, the factory coefficient was enough up to 2.0 %, which corresponds to dew point temperature of 18 °C. In conclusion, neither of factory corrections is enough for use all year round. So, the water vapor correction should be made for each gas analyzer when making high accuracy measurements. Due to cyclic drift of water vapor measurement, the correction should remain stable over time, but this needs further verification. Currently, the correction should be made at least once per year.
  • Boughdiri, Larbi (2022)
    The topic of thesis is the wave equation. The first chapter is introduction, the overview of the thesis is presented. The second chapter treats the transport equation, which is needed to solve the wave equation. In the third chapter we discuss the d’Alembert formula, and we prove the existence and uniqueness of solution. We treat the domain of dependence and region of influence. The last chapter concentrates on solving wave equations in high dimensions by Kirchhoff’s formula, method of descent and methods of spherical means.
  • Haataja, Anna (2020)
    The purpose of this thesis is to look from two different perspectives how wave equations can be solved. These are the forward problem of wave equations as partial differential equations of the initial or boundary-value type, and later in the framework of control theory. First, to provide a meaningful solution space, the basics of the theory of weak derivatives and Sobolev spaces are discussed along with some approximation, extension, and embedding theorems. Then, the initial or boundary value problem of the wave equation is defined, its weak solutions are constructed based on general hyperbolic partial differential equations, and the existence and uniqueness of said solutions is proved. The last part of this thesis concentrates on linear control theory: controllability of a linear system, and especially how it can be defined and proven form the first half of the last chapter. The other half is reserved for wave equations in control theory and why it is possible to reduce a wave control problem to solving the control problem of the aforementioned linear system.
  • Kankaanniemi, Marko (Helsingin yliopistoHelsingfors universitetUniversity of Helsinki, 2011)
    Google Wave is a real-time communication and collaboration system introduced in 2009. The Wave system allows multiple users to view and modify hosted conversations called waves simultaneously. A wave conversation consists of a tree-like structure of messages. The messages can contain rich text, images and other attachments. Concurrency control is handled using a technique called operational transformation. It enables users to modify a wave simultaneously without acquiring any locks. Google has released Wave protocol descriptions and other technical documentation about the implementation of Wave. Google has also released a large portion of Wave source code under an open source license. Google ended the development of Google Wave in the late 2010 but the development of Wave is continued by the Apache Software Foundation. The open source version of Wave is called Wave in a Box. Wave in a Box contains the implementations of a web-based client and a Wave server. Wave is based on a federated client-server architecture. Although the Wave client is connected only to the user's own Wave service provider, the user can still communicate with users of other service providers. Wave servers are connected to each other and communicate with each other transparently to the user. In this sense the Wave architecture resembles email architecture. In this thesis we present the design for a new peer-to-peer-based Wave system called P2P-Wave. P2P-Wave was designed to be much like the original Wave. Operational transformation is used in both systems and the same functionality is available to the user in both systems. However, the systems are very different with respect to network communication. P2P-Wave has no centralized servers; all communication happens between users' own computers through the Pastry routing system. P2P-Wave also uses the Scribe multicast system and the distributed file system Past.
  • Gibson, Clint (2017)
    Albert Einstein’s General Theory of Relativity radically transformed our understanding of gravitation. Along with this transformative view came several powerful predictions. One of these predictions, the deflection of light in a gravitational field, has proven in recent decades to be crucial to the study of cosmology. In this work we present the foundational theory of gravitational lensing, with a particular focus on the weak regime of lensing. Weak gravitational lensing produced by the large scale structure, called cosmic shear, induces percent level distortions in the images of distant galaxies. Gravitational lensing is of particular interest, since the image distortions are due to all of the matter in the large scale structure, including dark matter. We present the definitions of shear and convergence which are used to quantify the source galaxy image distortions, and discuss some techniques shown in literature which are used for measuring these quantities. This includes presenting the necessary derivations which connect these quantities to two particular classes of results: mass map reconstructions and cosmological parameter constraints. We present some results obtained in recent years: mass map reconstructions obtained using the Canada-France-Hawaii-Telescope Lensing Survey (CFHTLenS) and the Cosmological Evolution Survey (COSMOS), and constraints on the parameters Ω_m and σ_8 (the total matter density parameter and the power spectrum normalization) obtained using CFHTLenS, COSMOS, the Kilo Degree Survey (KiDS), and the Dark Energy Survey (DES). This includes some discussion of apparent tensions with results obtained from Planck (using observations of the cosmic microwave background—a completely different cosmological probe) and of some inconsistencies within the more recent survey results.
  • Kovanen, Ville (2021)
    Maxwell’s equations are a set of equations which describe how electromagnetic fields behave in a medium or in a vacuum. This means that they can be studied from the perspective of partial differential equations as different kinds of initial value problems and boundary value problems. Because often in physically relevant situations the media are not regular or there can be irregular sources such as point sources, it’s not always meaningful to study Maxwell’s equations with the intention of finding a direct solution to the problem. Instead in these cases it’s useful to study them from the perspective of weak solutions, making the problem easier to study. This thesis studies Maxwell’s equations from the perspective of weak solutions. To help understand later chapters, the thesis first introduces theory related to Hilbert spaces, weak derivates and Sobolev spaces. Understanding curl, divergence, gradient and their properties is important for understanding the topic because the thesis utilises several different Sobolev spaces which satisfy different kinds of geometrical conditions. After going through the background theory, the thesis introduces Maxwell’s equations in section 2.3. Maxwell’s equations are described in both differential form and timeharmonic differential forms as both are used in the thesis. Static problems related to Maxwell’s equations are studied in Chapter 3. In static problems the charge and current densities are stationary in time. If the electric field and magnetic field are assumed to have finite energy, it follows that the studied problem has a unique solution. The thesis demonstrates conditions on what kind of form the electric and magnetic fields must have to satisfy the conditions of the problem. In particular it’s noted that the electromagnetic field decomposes into two parts, out of which only one arises from the electric and magnetic potential. Maxwell’s equations are also studied with the methods from spectral theory in Chapter 4. First the thesis introduces and defines a few concepts from spectral theory such as spectrums, resolvent sets and eigenvalues. After this, the thesis studies non-static problems related to Maxwell’s equations by utilising their time-harmonic forms. In time-harmonic forms the Maxwell’s equations do not depend on time but instead on frequencies, effectively simplifying the problem by eliminating the time dependency. It turns out that the natural frequencies which solve the spectral problem we study belong to the spectrum of Maxwell’s operator iA . Because the spectrum is proved to be discrete, the set of eigensolutions is also discrete. This gives the solution to the problem as the natural frequency solving the problem has a corresponding eigenvector with finite energy. However, this method does not give an efficient way of finding the explicit form of the solution.
  • Salla, Anni (2019)
    Climate change is globally considered as one of the biggest threats to the economy and development. Agriculture is the sector that faces the heaviest consequences and agriculture is also the primary livelihood for 2.5 billion people. Especially vulnerable are those who rely on rain-fed agriculture and for them adequate information on weather and climate is essential, enabling the adaptation to climatic changes. Weather and climate information services (WCIS) which are the entity from the generation to the dissemination and utilization of the information, plays a significant role for farmers especially in the developing countries. Adequate information is accessible and accurate, also in terms of time and location, and is communicated in a way that enables using the information in practice. The connection between agricultural production and WCIS has been more acknowledged and most of the African countries are able to provide monthly and seasonal forecasts, agrometeorological forecasts and extreme weather event warnings. However, still many areas suffer from lack of information systems which would help farmers to plan their agricultural activities and to adopt better farming practices. This study focuses on the adequacy of WCIS through farmer’s experiences in the Taita Hills, Kenya. Using semi-structured interviews, it identifies ICT- and human-based sources, content, and utilization of the information and how the information is shared through social networks. Additionally, it acknowledges the role of traditional knowledge to forecast weather through indicators in the environment. Local subsistence farmers, who are the key informants of this study, have experienced the impacts of climate change mainly as delayed rain seasons and decreased rainfall as well as increased temperatures. Important weather information for the farmers, in terms of agriculture, is dominantly the information about the onset and volume of rainfall that is used to schedule farming practices to achieve successful yield. The results of the study indicate that ICT-based information sources, such as daily forecasts from the radio, do not offer useful information for the farmers due to high uncertainty. The main sources of weather and climate information are human-based sources such as chiefs’ barazas and agricultural extension officers which offer seasonal forecasts and guidance on suitable crop types and other agricultural counselling. The information is shared in a communicative way which enables a dialog between the source and the farmer. In addition to seasonal forecasts, farmers rely heavily on traditional knowledge and regard it as reliable since it is observed through own senses and has a long local history through generations. Social networks in general, including barazas and extension officers but also, for example, neighbours and farmer groups, play an essential role in sharing information. Farmers both receive and share information through several forums. However, there are still farmers that are excluded from any WCIS related social networks and hence lack capacity to adapt to climatic changes. There is still a need to develop extension services to reach everybody in need and to generate more locally accurate forecasts which require local weather data gathering. Also, there is great potential in ICT as an information dissemination tool to a large audience.
  • Rasheed, Junaid (2015)
    The World Wide Web has emerged as a powerful tool and an entity that has formed a major part of everyday human life. Since web technology has become vital to humans, it is emerging as a platform where web applications mean more than they have ever meant. This demands for the user experience to be pleasurable and fast. But the disruptions in flow in traditional web applications stop the user from getting the desired experience. Initially web browsers were developed for displaying static pages linked together and user navigated to retrieve information from a server. This phenomenon is also known as multipage paradigm. It took more than two decades to evolve from a mere information-displaying entity to an application execution platform. The Ubiquitous nature of the web changed the trends, and complex web applications started emerging. These applications on user actions reload the entire web page from the server. Client and server communicate using synchronous communication mode. User action on the client triggers a call to the server and blocks the input/output until the server responds. Even after the advancement of web technologies, the web applications multipage paradigm remains the same and so do the problems of disruption in the user experience and application workflow. This thesis analyzes the design and development of modern web applications aimed at providing new single page paradigm and asynchronous communication between the client and the server to solve problems found in the multipage web application paradigm. This thesis also discusses the tools and technologies used in building single page web applications. The new single page paradigm introduces some challenges that are also considered in this thesis. Furthermore, the thesis covers that how the new paradigm can be used to develop applications on fragmented devices. Finally, the thesis describes the implementation of an example application aimed at producing a single page paradigm.
  • Zhen, Shi (2020)
    Location tracking has been quite an important tool in our daily life. The outdoor location tracking can easily be supported by GPS. However, the technology of tracking smart device users indoor position is not at the same maturity level as outdoor tracking. AR technology could enable the tracking on users indoor location by scanning the AR marker with their smart devices. However, due to several limitations (capacity, error tolerance, etc.) AR markers are not widely adopted. Therefore, not serving as a good candidate to be a tracking marker. This paper carries out a research question whether QR code can replace the AR marker as the tracking marker to detect smart devices’ user indoor position. The paper has discussed the research question by researching the background of the QR code and AR technology. According to the research, QR code should be a suitable choice to implement as a tracking marker. Comparing to the AR marker, QR code has a better capacity, higher error tolerance, and widely adopted. Moreover, a web application has also been implemented as an experiment to support the research question. It utilized QR code as a tracking marker for AR technology which built a 3D model on the QR code. Hence, the position of the user can be estimated from the 3D model. This paper discusses the experiment result by comparing a pre-fixed target user’s position and real experiment position with three different QR code samples. The limitation of the experiment and improvement ideas have also been discussed in this paper. According to the experiment, the research question has being answered that a combination of QR code and AR technology could deliver a satisfying indoor location result in a smart device user.
  • Sinisalo, Seppo Hannu Ilari (2018)
    Welcome, in this thesis, some of the higher ranked, popular web content management software (CMS), namely Drupal, WordPress, Joomla and Plone, are compared by usability, from a developer’s perspective, and by performance of the resultant site build with these CMSs, to find out, among other topics, about their potential to build websites to different needs. This thesis tries to discover if a CMS exists, in this selected group, that is a clear choice above the others in both usability and performance. A substantial portion of source material for this research comes from measurements, and small demo systems built and used, in addition to any literature sources used and experience garnered from career as a web developer. In this thesis, we provide an overview of these four selected CMS; their characteristics, statistics and how they measure up to each other. And so doing, expand upon the still narrow research done in this field.
  • Luostarinen, Veera (Helsingin yliopistoUniversity of HelsinkiHelsingfors universitet, 2001)
  • Magnússon, Joonas (2019)
    Tässä tutkielmassa vertaillaan vertaillaan keskenään web-sovellusten käyttöliittymien automaattitestauksen menetelmiä. Tutkielmassa selvitetään mitä erityistä webohjelmistojen testaamisessa on, ja miten niitä on mahdollista testata. Tutkielmassa vertaillaan myös muutamia testiautomaation tekniikoita ja niitä hyödyntäviä ohjelmointikirjastoja ja työkaluja. Cypress on Javascript-pohjainen testiautomaatio kehys web-ohjelmistojen testaamiseen. Selenium Webdriver on Wedriver protokollaa hyödyntävä selainautomaatiokirjasto, jota käytetään mm. selainohjelmistojen testaamiseen. Sikuli on automaatiokirjasto, joka perustuu kuvantunnistukseen. Näitä kirjastoja ja niiden soveltamia tekniikoita vertaillaan keskenään niiden webohjelmistojen testaamiseen soveltuvuuden, testien kehityksen ja suorituksen tehokkuuden sekä alusta- ja selaintuen näkökulmista.
  • Pakarinen, Eveliina (2020)
    Tässä tutkielmassa ohjelmiston vaiheittaisella käyttöönotolla tarkoitetaan sitä, että ohjelmiston käyttäjille annetaan vaiheittain pääsy tuotantoon vietyyn ohjelmistoon. Otettaessa ohjelmistoa vaiheittain käyttöön annetaan tuotantoon vietyyn ohjelmistoon aluksi pääsy esimerkiksi vain tietylle osajoukolle ohjelmiston käyttäjistä. Tämän jälkeen kasvatetaan vaiheittain käyttäjien pääsyä ohjelmistoon. Vaiheittainen käyttöönotto päättyy, kun kaikille ohjelmiston käyttäjille on annettu pääsy ohjelmistoon. Tässä tutkielmassa kehitettiin menetelmä web-ohjelmiston uuden version vaiheittaiselle käyttöönotolle ympäristöön, jossa vaatimuksena on palvelun käytön katkottomuus. Tutkielman tutkimuskysymyksenä on, miten web-ohjelmiston vaiheittainen käyttöönotto voidaan toteuttaa käytännössä. Tutkielma toteutettiin ohjelmistopalveluita tarjoavalle kohdeyritykselle, joka toimii yritykseltä-yritykselle-toimialalla. Tutkimusmenetelmänä tutkielmassa käytettiin design science -tutkimusmenetelmää. Tutkielman aikana kehitettiin AphoDeploy-sovellus, jonka avulla vaiheittainen käyttöönotto voitiin automatisoida Kubernetes-klusterissa. Kubernetes-klusteriin asennettiin palveluverkkoratkaisu, jonka tarjoamien välityspalvelinten avulla Kubernetes-klusterissa tehtiin ajonaikaista liikenteenohjausta. AphoDeploy-sovelluksen avulla toteutettiin uuden ohjelmistoversion vaiheittainen käyttöönotto muuttamalla palveluverkkoratkaisun ja Kubernetes-klusterin konfiguraatioita automatisoidusti. Vaiheittaisen käyttöönoton menetelmän toimintaa tutkittiin muun muassa automatisoiduilla testitapauksilla, joiden avulla selvitettiin, toteuttaako menetelmä vaiheittaiselle käyttöönotolle asetetut vaatimukset. Vaatimukset jaoteltiin teknisiin vaatimuksiin, vaiheittaisen käyttöönoton vaatimuksiin ja vaiheittaisen käyttöönoton päättymisen vaatimuksiin. Vaiheittaisen käyttöönoton menetelmän arvioinnin perusteella voitiin todeta, että kahdeksasta vaiheittaiselle käyttöönotolle asetetusta vaatimuksesta seitsemän vaatimusta täyttyi kokonaan ja yksi vaatimus täyttyi osittain. Tutkielmassa löydettiin tapa toteuttaa web-ohjelmiston vaiheittainen käyttöönotto käytännössä AphoDeploy-sovelluksen avulla. Näin ollen tutkielmassa löydettiin vastaus tutkielman tutkimuskysymykseen. Tutkielman aikana kehitetyn menetelmän avulla luotiin lisäksi pohjaa työkaluinfrastruktuurille, joka voisi tulevaisuudessa tukea kohdeyrityksessä esimerkiksi tuotannossa tehtävää kokeilua. Vaiheittaisen käyttöönoton menetelmän arvioinnin perusteella AphoDeploy-sovelluksesta löydettiin tulevaisuutta varten myös mahdollisia jatkokehityskohteita. ACM Computing Classification System (CCS): - Software and its engineering -> Software organization and properties -> Contextual software domains -> Software infrastructure -> Middleware - General and reference -> Cross-computing tools and techniques -> Experimentation
  • Rask, Tobias (2013)
    Web-palvelut ovat tekniikkana suosittu tapa toteuttaa yritysten sisäiset ja ulkoiset liiketoimintaprosessit sähköisenä palveluna. Koostamisen avulla olemassa olevista web-palveluista voidaan rakentaa uusia monipuolisempia palveluja. Tässä työssä tutkitaan, minkälainen transaktionaalisuuden taso koosteisessa web-palvelussa voidaan saavuttaa käytettävissä olevilla teknologioilla. Tämä tehdään vertailemalla web-palveluiden transaktionaalisia ominaisuuksia tietokantateoriasta tuttuihin transaktion ACID-ominaisuuksiin, sarjallistuvuusteoriaan, sekä transaktiomalleihin. Työssä tutkitaan myös sitä, tarvitaanko web-palveluiden transaktionaalisessa koostamisessa ylipäätään tietokantojen teoriasta tuttuja käsitteitä ja malleja. Tutkimuksessa syvennytään niihin web-palveluiden koostamisessa käytettäviin menetelmiin ja protokolliin, jotka tarjoavat transaktionaalisia piirteitä liiketoimintaprosessien toteuttamiseksi. Nämä ovat web-arkkitehtuuripinon WS-AtomicTransaction- ja WS-BusinessActivity -protokollat. Tulosten analysoinnissa on käytetty apuna erään matkatoimiston web-palvelua. Web-palveluiden välisten transaktioiden ACID-ominaisuudet käytiin läpi kahden web-palvelun käyttötapauksen kautta. Tuloksista selvisi, että web-palveluiden välisissä transaktioissa toteutuu ainoastaan transaktion ACID-atomisuus. Samalla selvitettiin, miten tämä saavutettu transaktionaalisuuden taso käytännössä vaikuttaa web-palveluiden väliseen toimintaan. Tutkielman tuloksien vaikutuksia web-palveluiden väliseen kanssakäyntiin arvioitiin sekä palvelun toteuttajan, että loppukäyttäjän näkökulmasta. Tuloksien perusteella kävi ilmi, että vakavien ongelmien välttämiseksi toteuttajan on tunnettava sovelluksen ongelmakenttä erityisen hyvin ja ymmärrettävä se, miten koosteisen web-palvelun transaktionaalisuuden taso vaikuttaa kyseisessä ympäristössä palvelun toimintaan. Tutkielman lopussa esitellään tämän tutkielman tuloksena syntynyt eksklusiivinen malli, jonka avulla koosteeseen osallistuvien web-palveluiden välisissä transaktioissa voidaan saavuttaa globaali ACID-eristyvyys. Mallia soveltamalla web-palvelut voivat etsiä eksklusiivista kauppaa käyviä web-palveluja SOA-arkkitehtuurimallin mukaisesti UDDI-rekisteristä, ja suorittaa näiden kanssa häiriöttämästi sarjallistuvia transaktioita. ACM Computing Classification System (CCS): - Information systems~Web services - Information systems~Database transaction processing