Kiinteän pilkun laskenta sulautetussa järjestelmässä

Floating-point and fixed-point calculations in an embedded system are the focus of this study; in particular, in this research, an embedded system is defined as a valve positioner (made by Metso Automation) controlled by a microcontroller. Moreover, one of the significant causes of load in a microcontroller is known to be floating-point arithmetic. Thus the aim of this study is to create a fixed-point data type which replaces floating-point arithmetic if fixed-point arithmetic can be proven to reduce the load of the microcontroller, and retain reliable accuracy. In addition to this, a fixed-point data type must be scalable and transferable to various HW/SW-environments. The theoretical part of this thesis is based on a thorough review of earlier research and, moreover, explicates the demanding application environment of a valve package. A valve package consists of an industry valve, an actuator and a valve positioner. This thesis focuses on an ARM-based microcontroller in a valve positioner. The theoretical part explicates the relevant data type's e.g. floating-point numbers, integers and fixed-point numbers and their sizes and structures. A demonstration is given in the experimental section of how a fixed-point data type is created based on the theoretical part with an oscilloscope being used to measure the speed of floating-point and fixed-point arithmetic. Some fixed-point models are explained and one of the previous ones is chosen for further tests. The criteria for a chosen fixed-point model are extensibility and accuracy. A chosen fixed-point model is verified against accuracy and speed. This thesis demonstrates the processes of floating-point and fixed-point calculation as well as their requirements. Finally, the thesis proposes some ideas for further development of fixed-point calculation.Tässä diplomityössä on tutkittu liukuluku- ja kiinteän pilkun laskentaa sulautetussa järjestelmässä. Tässä tapauksessa sulautettu järjestelmä on Metso Automationin valmistama digitaalinen venttiiliohjain, jota ohjaa mikrokontrolleri. Liukulukulaskennan on todettu olevan yksi merkittävä mikrokontrollerin kuormittaja. Tarkoituksena on luoda kiinteän pilkun tietotyyppi ja korvata sillä liukulukulaskenta, jos kiinteän pilkun laskenta pienentää mikrokontrollerin kuormitusta ja omaa hyvän tarkkuuden. Tämän lisäksi kiinteän pilkun tietotyypin tulee olla laajennettava ja olla siirrettävissä erilaisiin HW/SW-ympäristöihin. Diplomityön teoriaosa muodostettiin kirjallisuustutkimuksen avulla. Teoriaosassa esitellään haastavaa sovellusympäristöä, joka on venttiilipaketti. Venttiilipaketin muodostavat teollisuusventtiili, toimilaite ja venttiiliohjain. Venttiiliohjaimessa keskitytään mikrokontrolleriin, joka on ARM-pohjainen. Teoriaosa esittelee asiaan kuuluvat tietotyypit, kuten esimerkiksi liukuluvut, kokonaisluvut ja kiinteän pilkun luvut. Em. tietotyypeistä käydään läpi niiden kokoa ja rakennetta. Diplomityön kokeellisessa osassa muodostetaan kiinteän pilkun tietotyyppi teoriaosasta saatujen tietojen perusteella. Liukuluku- ja kiinteän pilkun laskennan nopeutta mitataan oskilloskoopin avulla. Kokeellinen osa esittelee useita toteutusmalleja, joista valitaan yksi. Kriteerinä valinnalle on sen laajennettavuus ja sen tarkkuus. Valittu kiinteän pilkun toteutusmalli verifioidaan tarkkuuden ja nopeuden suhteen. Tämä diplomityö opettaa ymmärtämään liukuluku- ja kiinteän pilkun laskentaa sekä niiden vaatimuksia. Diplomityön lopuksi kiinteälle pilkulle esitetään jatkokehityssuunnitelma

CT or Invasive Coronary Angiography in Stable Chest Pain.

Background: In the diagnosis of obstructive coronary artery disease (CAD), computed tomography (CT) is an accurate, noninvasive alternative to invasive coronary angiography (ICA). However, the comparative effectiveness of CT and ICA in the management of CAD to reduce the frequency of major adverse cardiovascular events is uncertain. Methods: We conducted a pragmatic, randomized trial comparing CT with ICA as initial diagnostic imaging strategies for guiding the treatment of patients with stable chest pain who had an intermediate pretest probability of obstructive CAD and were referred for ICA at one of 26 European centers. The primary outcome was major adverse cardiovascular events (cardiovascular death, nonfatal myocardial infarction, or nonfatal stroke) over 3.5 years. Key secondary outcomes were procedure-related complications and angina pectoris. Results: Among 3561 patients (56.2% of whom were women), follow-up was complete for 3523 (98.9%). Major adverse cardiovascular events occurred in 38 of 1808 patients (2.1%) in the CT group and in 52 of 1753 (3.0%) in the ICA group (hazard ratio, 0.70; 95% confidence interval [CI], 0.46 to 1.07; P = 0.10). Major procedure-related complications occurred in 9 patients (0.5%) in the CT group and in 33 (1.9%) in the ICA group (hazard ratio, 0.26; 95% CI, 0.13 to 0.55). Angina during the final 4 weeks of follow-up was reported in 8.8% of the patients in the CT group and in 7.5% of those in the ICA group (odds ratio, 1.17; 95% CI, 0.92 to 1.48). Conclusions: Among patients referred for ICA because of stable chest pain and intermediate pretest probability of CAD, the risk of major adverse cardiovascular events was similar in the CT group and the ICA group. The frequency of major procedure-related complications was lower with an initial CT strategy. (Funded by the European Union Seventh Framework Program and others; DISCHARGE ClinicalTrials.gov number, NCT02400229.)