Business potential evaluation of wireless local area networks: Teleoperator’s view

The objective of the thesis was to evaluate business potential of wireless local area networks (WLAN, Wireless LAN). At first, the scope of business potential evaluation of technology was introduced. Next, a general framework of business potential evaluation of technology based on literature was presented. In addition, convergence of cellular networks and data networks was studied in order to get an insight of current situation of mobile telecommunications industry. Finally, wireless local area networks business potential was evaluated. A wireless local area network is a data communication system, which combines data connectivity with mobility and is implemented in unlicensed frequency bands, allowing new business opportunities to emerge. The main markets of WLAN are corporate networks, public area networks and access networks. At the moment the penetration of WLAN terminals is low which derives to low demand of wireless LAN services. In addition, unlicensed spectrum forces the teleoperators to set the service price relatively low. The business potential is in integrating wireless LANs to cellular networks and in offering value added services to end users. The future of wireless LAN is to be complementary network to cellular networks. In this vision cellular networks provide voice and low data services and broadband wireless networks enable multimedia services.

Readout schemes for low noise single-photon avalanche diodes fabricated in conventional HV-CMOS technologies

Three different pixels based on single-photon avalanche diodes for triggered applications, such as fluorescence lifetime measurements and high energy physics experiments, are presented. Each pixel consists of a 20µm x 100µm (width x length) single photon avalanche diode and a monolithically integrated readout circuit. The sensors are operated in the gated mode of acquisition to reduce the probability to detect noise counts interferring with real radiation events. Each pixel includes a different readout circuit that allows to use low reverse bias overvoltages. Experimental results demonstrate that the three pixels present a similar behaviour. The pixels get rid of afterpulses and present a reduced dark count probability by applying the gated operation. Noise figures are further improved by using low reverse bias overvoltages. The detectors exhibit an input dynamic range of 13.35 bits with short gated"on" periods of 10ns and a reverse bias overvoltage of 0.5V. The three pixels have been fabricated in a standard HV-CMOS process.

Is the matching function Cobb-Douglas?

[cat] Estudiem les propietats teòriques que una funció d.emparellament ha de satisfer per tal de representar un mercat laboral amb friccions dins d'un model d'equilibri general amb emparellament aleatori. Analitzem el cas Cobb-Douglas, CES i altres formes funcionals per a la funció d.emparellament. Els nostres resultats estableixen restriccions sobre els paràmetres d'aquests formes funcionals per assegurar que l.equilibri és interior. Aquestes restriccions aporten raons teòriques per escollir entre diverses formes funcionals i permeten dissenyar tests d'error d'especificació de model en els treballs empírics.

Is the matching function Cobb-Douglas?

[cat] Estudiem les propietats teòriques que una funció d.emparellament ha de satisfer per tal de representar un mercat laboral amb friccions dins d'un model d'equilibri general amb emparellament aleatori. Analitzem el cas Cobb-Douglas, CES i altres formes funcionals per a la funció d.emparellament. Els nostres resultats estableixen restriccions sobre els paràmetres d'aquests formes funcionals per assegurar que l.equilibri és interior. Aquestes restriccions aporten raons teòriques per escollir entre diverses formes funcionals i permeten dissenyar tests d'error d'especificació de model en els treballs empírics.

Text Classification and Indexing in IP Networks

Internet on elektronisen postin perusrakenne ja ollut tärkeä tiedonlähde akateemisille käyttäjille jo pitkään. Siitä on tullut merkittävä tietolähde kaupallisille yrityksille niiden pyrkiessä pitämään yhteyttä asiakkaisiinsa ja seuraamaan kilpailijoitansa. WWW:n kasvu sekä määrällisesti että sen moninaisuus on luonut kasvavan kysynnän kehittyneille tiedonhallintapalveluille. Tällaisia palveluja ovet ryhmittely ja luokittelu, tiedon löytäminen ja suodattaminen sekä lähteiden käytön personointi ja seuranta. Vaikka WWW:stä saatavan tieteellisen ja kaupallisesti arvokkaan tiedon määrä on huomattavasti kasvanut viime vuosina sen etsiminen ja löytyminen on edelleen tavanomaisen Internet hakukoneen varassa. Tietojen hakuun kohdistuvien kasvavien ja muuttuvien tarpeiden tyydyttämisestä on tullut monimutkainen tehtävä Internet hakukoneille. Luokittelu ja indeksointi ovat merkittävä osa luotettavan ja täsmällisen tiedon etsimisessä ja löytämisessä. Tämä diplomityö esittelee luokittelussa ja indeksoinnissa käytettävät yleisimmät menetelmät ja niitä käyttäviä sovelluksia ja projekteja, joissa tiedon hakuun liittyvät ongelmat on pyritty ratkaisemaan.

Software methods for HTML files protection in local / corporate networks: review and implementation

Tässä luomistyössä on esitetty tutkimus informaation suojaamisen menetelmien osalta paikallisissa ja ryhmäkuntaisissa verkoissa. Tutkimukseen kuuluu nykyaikaisten kryptagraafisten järjestelmien, Internetin/Intranetin ohjelmointikeinojen ja pääsyoikeuksien jakelumenetelmien analyysi. Tutkimusten perusteella on laadittu ohjelmiston prototyyppi HTML-tiedostojen suojaamista varten. Ohjelmiston laatimisprosessi on sisältänyt vaatimusten, järjestelmän ja suojelukomponenttien suunnittelun ja protytyypin testauksen. Ohjelmiston realisoinnin jälkeen kirjoitettiin käyttöohjeet. Ohjelmiston prototyyppi suojaa informaatiota HTML-tiedoston koko käytön aikana ja eri yrityksissä voidaan käyttää sitä pienien laajennuksien jälkeen.

Delivery system for location based information in wireless IP networks

Tämä työ esittelee uuden tarjota paikasta riippuvaa tietoa langattomien tietoverkkojen käyttäjille. Tieto välitetään jokaiselle käyttäjälle tietämättä mitään käyttäjän henkilöllisyydestä. Sovellustason protokollaksi valittiin HTTP, joka mahdollistaa tämän järjestelmän saattaa tietoa perille useimmille käyttäjille, jotka käyttävät hyvinkin erilaisia päätelaitteita. Tämä järjestelmä toimii sieppaavan www-liikenteen välityspalvelimen jatkeena. Erilaisten tietokantojen sisällä on perusteella järjestelmä päättää välitetäänkö tietoa vai ei. Järjestelmä sisältää myös yksinkertaisen ohjelmiston käyttäjien paikantamiseksi yksittäisen tukiaseman tarkkuudella. Vaikka esitetty ratkaisu tähtääkin paikkaan perustuvien mainosten tarjoamiseen, se on helposti muunnettavissa minkä tahansa tyyppisen tiedon välittämiseen käyttäjille.

No Major Differences Found between the Effects of Microwave-Based and Conventional Heat Treatment Methods on Two Different Liquid Foods

Extension of shelf life and preservation of products are both very important for the food industry. However, just as with other processes, speed and higher manufacturing performance are also beneficial. Although microwave heating is utilized in a number of industrial processes, there are many unanswered questions about its effects on foods. Here we analyze whether the effects of microwave heating with continuous flow are equivalent to those of traditional heat transfer methods. In our study, the effects of heating of liquid foods by conventional and continuous flow microwave heating were studied. Among other properties, we compared the stability of the liquid foods between the two heat treatments. Our goal was to determine whether the continuous flow microwave heating and the conventional heating methods have the same effects on the liquid foods, and, therefore, whether microwave heat treatment can effectively replace conventional heat treatments. We have compared the colour, separation phenomena of the samples treated by different methods. For milk, we also monitored the total viable cell count, for orange juice, vitamin C contents in addition to the taste of the product by sensory analysis. The majority of the results indicate that the circulating coil microwave method used here is equivalent to the conventional heating method based on thermal conduction and convection. However, some results in the analysis of the milk samples show clear differences between heat transfer methods. According to our results, the colour parameters (lightness, red-green and blue-yellow values) of the microwave treated samples differed not only from the untreated control, but also from the traditional heat treated samples. The differences are visually undetectable, however, they become evident through analytical measurement with spectrophotometer. This finding suggests that besides thermal effects, microwave-based food treatment can alter product properties in other ways as well.

Multicontrast connectometry: A new tool to assess cerebellum alterations in early relapsing-remitting multiple sclerosis.

BACKGROUND: Cerebellar pathology occurs in late multiple sclerosis (MS) but little is known about cerebellar changes during early disease stages. In this study, we propose a new multicontrast "connectometry" approach to assess the structural and functional integrity of cerebellar networks and connectivity in early MS. METHODS: We used diffusion spectrum and resting-state functional MRI (rs-fMRI) to establish the structural and functional cerebellar connectomes in 28 early relapsing-remitting MS patients and 16 healthy controls (HC). We performed multicontrast "connectometry" by quantifying multiple MRI parameters along the structural tracts (generalized fractional anisotropy-GFA, T1/T2 relaxation times and magnetization transfer ratio) and functional connectivity measures. Subsequently, we assessed multivariate differences in local connections and network properties between MS and HC subjects; finally, we correlated detected alterations with lesion load, disease duration, and clinical scores. RESULTS: In MS patients, a subset of structural connections showed quantitative MRI changes suggesting loss of axonal microstructure and integrity (increased T1 and decreased GFA, P < 0.05). These alterations highly correlated with motor, memory and attention in patients, but were independent of cerebellar lesion load and disease duration. Neither network organization nor rs-fMRI abnormalities were observed at this early stage. CONCLUSION: Multicontrast cerebellar connectometry revealed subtle cerebellar alterations in MS patients, which were independent of conventional disease markers and highly correlated with patient function. Future work should assess the prognostic value of the observed damage. Hum Brain Mapp 36:1609-1619, 2015. © 2014 Wiley Periodicals, Inc.

On the Analysis and Control of a Linear Synchronous Servomotor with a Flexible Load

Industry's growing need for higher productivity is placing new demands on mechanisms connected with electrical motors, because these can easily lead to vibration problems due to fast dynamics. Furthermore, the nonlinear effects caused by a motor frequently reduce servo stability, which diminishes the controller's ability to predict and maintain speed. Hence, the flexibility of a mechanism and its control has become an important area of research. The basic approach in control system engineering is to assume that the mechanism connected to a motor is rigid, so that vibrations in the tool mechanism, reel, gripper or any apparatus connected to the motor are not taken into account. This might reduce the ability of the machine system to carry out its assignment and shorten the lifetime of the equipment. Nonetheless, it is usually more important to know how the mechanism, or in other words the load on the motor, behaves. A nonlinear load control method for a permanent magnet linear synchronous motor is developed and implemented in the thesis. The purpose of the controller is to track a flexible load to the desired velocity reference as fast as possible and without awkward oscillations. The control method is based on an adaptive backstepping algorithm with its stability ensured by the Lyapunov stability theorem. As a reference controller for the backstepping method, a hybrid neural controller is introduced in which the linear motor itself is controlled by a conventional PI velocity controller and the vibration of the associated flexible mechanism is suppressed from an outer control loop using a compensation signal from a multilayer perceptron network. To avoid the local minimum problem entailed in neural networks, the initial weights are searched for offline by means of a differential evolution algorithm. The states of a mechanical system for controllers are estimated using the Kalman filter. The theoretical results obtained from the control design are validated with the lumped mass model for a mechanism. Generalization of the mechanism allows the methods derived here to be widely implemented in machine automation. The control algorithms are first designed in a specially introduced nonlinear simulation model and then implemented in the physical linear motor using a DSP (Digital Signal Processor) application. The measurements prove that both controllers are capable of suppressing vibration, but that the backstepping method is superior to others due to its accuracy of response and stability properties.

Nature of the Epidemic Threshold for the Susceptible-Infected-Susceptible Dynamics in Networks

We develop an analytical approach to the susceptible-infected-susceptible epidemic model that allows us to unravel the true origin of the absence of an epidemic threshold in heterogeneous networks. We find that a delicate balance between the number of high degree nodes in the network and the topological distance between them dictates the existence or absence of such a threshold. In particular, small-world random networks with a degree distribution decaying slower than an exponential have a vanishing epidemic threshold in the thermodynamic limit.