Heat Consumption Assessment of the Domestic Hot Water Systems in the Apartment Buildings

This study presents the analysis of energy consumption for domestic hot water in apartment buildings in Riga, Latvia. The aggregate data contains information about 39 apartment buildings, including heat energy consumption and domestic hot water (DHW) consumption. The analysis is focused on the heat energy consumption and seasonal characteristics in the DHW system.The analysis characterizes the DHW consumption, energy consumption for DHW and energy losses in the DHW systems in apartment buildings

Fin type propulsive devices with varying working area of vibrating tail

The object of the study is a fin type propulsive device of robotic fish moving inside water. The aim of the study is to establish optimal control law for variation of additional area of vibrating tail, which ensures maximal positive impulse of motive forces acting on tail. The problem has been solved using the maximum principle of Pontryagin. It is demonstrated that optimal control action corresponds to the case of bound values of area limits. The proposed method makes it possible to increase effective surface area of the fin within motion cycles, when useful tractive force is formed. But within cycles, when fin motion is hindered by water resistance forces, effective surface area is decreased. Thanks to this energy losses are minimized, and operation of fin propulsive device becomes more effective. Examples on synthesis of real mechatronic systems are provided as wel

Bark disorders and manganese nutrition of some fruit trees in the Goulburn Valley

Some Delicious apple trees growing in the Goulburn Valley and adjacent areas show "measles", an internal bark necrosis with elevated pustules distributed over the bark surface. Wood which is one or more years old is affected. The pustules increase in number and size as the disorder becomes more severe. In the cortex underneath the bark epidermis, necrotic spots are found in great numbers, being largest beneath the epidermal elevations. In severe cases, cracking and splitting of the bark occurs, mainly on older wood; the affected trees have fewer and smaller leaves than normal; twigs and limbs die back; and eventually the whole tree may die. Another bark disorder, known as "papery bark", is fairly common on Josephine pears in the Goulburn Valley. The symptoms are an internal bark necrosis with cracking and rolling back of the bark epidermis on shoots and twigs one or more years old. The symptoms of a further disorder, known locally as "leaf spotting are more severe on these trees affected with "papery bark", and in addition fruit on such trees or limbs shows more "russeting" than is normal. Die-back of shoots and limbs often follows. The cause of these nutritional disorders, "bark measles" on Delicious apples and "papery bark" on Josephine pears, was investigated. The analysis of fresh tissues showed increased amounts of manganese in leaves, fruit and, bark of affected apple trees and in the leaves, bark, buds and fruit of affected pear trees. To demonstrate that excess uptake of manganese was the cause of these disorders, hydrated manganese sulphate was injected into trees of healthy appearance showing low manganese content in their fresh tissues. After this injection, disorders similar to "bark measles" and "papery bark" were produced on apples and pears respectively. Soil acidification with chemicals in the field and soil waterlogging in pots also produced "papery bark" on pears, while soil waterlogging in pots produced "bark measles" on apples. Analysis showed increased amounts of soluble manganese in treated soils and in the tissues of affected plants growing on treated soils. Laboratory trials with soils from orchards, both healthy and with manganese toxicity (hereafter called "toxic soils"), showed that drying, heating and waterlogging, especially at temperatures of 20 degree Celsius or more, also contribute to the release of high amounts of soluble manganese. These trials showed the importance of moisture conditions and pH in the recovery of toxic soils

Nošķelta cilindra kustība pa slīpu plakni

Pētot nošķelta cilindra kustību pa slīpu plakni, par pamatu jāņem bāzes figūra – cilindrs. Aprēķinam pieņemam, ka cilindra kustība pa slīpo plakni ir kopplāna t. i. Moments ap y asi ir 0. Aplūkojot praktiski un aprēķinot teorētiski pierādās, ka nenošķelta cilindra kustība pa slīpu plakni lineāri pieaug līdz pat bezgalībai. Cilindra kustības ātrums un paātrinājums ir atkarīgs gan no plaknes slīpuma leņķa  gan no ķermeņa masas. nenošķelts cilindrs nošķelts cilindrs Lai pētītu nošķelta cilindra kustību pa slīpu plakni mēs izmantojam kustības daudzuma momenta teorēmu un ar programmas Mathcad 2001 Professional palīdzību aprēķinam dažādus lielumus, kuri praktiski pētot nošķelta cilindra kustību pa slīpu plakni pierādījās

Inženierzinātnes un inženierizglītība Rīgas Tehniskajā universitātē

Rakstā aplūkota Rīgas Tehniskās universitātes – Latvijas Universitātes priekšteces – vieta un loma Latvijas zinātnes un izglītības sistēmā vēsturiskā aspektā un arī šīsdienas skatījumā

Применение современных технологий в процессе преподавания теоретической механики

Рассмотрен опыт преподавания ТЕОРЕТИЧЕСКОЙ МЕХАНИКИ в РИЖСКОМ ТЕХНИЧЕСКОМ УНИВЕРСИТЕТЕ: создание и применение материалов лекций в формате PowerPoint, использование анимации и ресурсов INTERNET, программы MathCad; индивидуализация заданий для самостоятельных работ студентов; разработка системы контроля знаний на основе результатов многолетней работы коллектива кафедры; использование портала е-обучения RTU ORTUS; реализация возможностей технологий Skype для удаленного и индивидуального обучения и контактов