Multifocal diffractive lens generating several fixed foci at different design wavelengths

We propose a method for designing multifocal diffractive lenses generating prescribed sets of foci with fixed positions at several different wavelengths. The method is based on minimizing the difference between the complex amplitudes of the beams generated by the lens microrelief at the design wavelengths, and the functions of the complex transmission of multifocal lenses calculated for these wavelengths. As an example, a zone plate generating three fixed foci at three different wavelengths was designed, fabricated, and experimentally investigated. The proof-of-concept experimental results confirm the formation of foci with fixed positions at the design wavelengths. The obtained results may find applications in the design and fabrication of novel multifocal contact and intraocular lenses with reduced chromatic effects

Application of nanoimprinting technique for fabrication of trifocal diffractive lens with sine-like radial profile

The fabrication of submicron-height sine-like relief of a trifocal diffractive zone plate using a nanoimprinting technique is studied. The zone plate is intended for use in combined trifocal diffractive-refractive lenses and provides the possibility to form trifocal intraocular lenses with predetermined light intensity distribution between foci. The optical properties of the designed zone plate having the optical powers 3 D, 0, -3D in the three main diffraction orders are theoretically and experimentally investigated. The results of the theoretical investigations are in good agreement with experimental measurements. The effects of the pupil size (lens diameter) as well as the wavelength-dependent behavior of the zone plate are also discussed

The Forest Observation System, building a global reference dataset for remote sensing of forest biomass

International audienceForest biomass is an essential indicator for monitoring the Earth's ecosystems and climate. It is a critical input to greenhouse gas accounting, estimation of carbon losses and forest degradation, assessment of renewable energy potential, and for developing climate change mitigation policies such as REDD+, among others. Wall-to-wall mapping of aboveground biomass (aGB) is now possible with satellite remote sensing (RS). However, RS methods require extant, up-to-date, reliable, representative and comparable in situ data for calibration and validation. Here, we present the Forest Observation System (FOS) initiative, an international cooperation to establish and maintain a global in situ forest biomass database. aGB and canopy height estimates with their associated uncertainties are derived at a 0.25 ha scale from field measurements made in permanent research plots across the world's forests. all plot estimates are geolocated and have a size that allows for direct comparison with many RS measurements. The FOS offers the potential to improve the accuracy of RS-based biomass products while developing new synergies between the RS and ground-based ecosystem research communities

LIIKETOIMINNAN ALOITTAMINEN VENÄJÄLLÄ

Tämän tutkimuksen tarkoituksena oli selvittää keskeisiä asioita liiketoiminnan aloittamisesta Venäjällä. Vaikka kyseessä ei ollutkaan suora toimeksianto, opinnäytetyön aihe syntyi erään yrityksen tarpeesta perustaa yritys Venäjälle. Tästä syystä tutkimus tehtiin suomalaisen yrityksen näkökulmasta. Tutkimuksessa jätettiin pois erilaiset etabloitumismuodot, sillä niistä löytyy tutkimuksia runsaasti jo ennestäänkin. Sen sijaan keskityttiin yrityksen sekä edustuston perustamisprosesseihin, sekä käytiin läpi Venäjällä tänä päivänä käytössä olevat yritysmuodot. Mukaan on otettu myös muita asioita liiketoiminnan aloittamisen ympäriltä, esimerkiksi henkilöstön palkkaaminen, toimitilat, tavaramerkin suojaaminen sekä yritysturvallisuuden järjestäminen. Venäjä tunnetaan erittäin byrokraattisena maana ja tämä tutkimus myös vahvisti nämä luulot. Yrityksen perustamiseen tarvittavia lomakkeita ja todistuksia on pitkät listat. Samoin virastoja, joihin asiakirjat on toimitettava määrätyssä järjestyksessä. Ainakin suomalaiselle tämä saattaa tuntua lähes pelottavalta. Tutkimus osoitti kuitenkin myös, että byrokratian ja muidenkin haasteiden hallitsemiseen on saatavilla apua, niin Suomen kuin Venäjänkin päässä. Kirjallisten lähteiden lisäksi tutkimuksessa on käytetty muun muassa Suomalais-Venäläisen kauppakamarin seminaaria sekä haastateltiin kahta venäläistä yrittäjää ja yhtä suomalaista myyntipäällikköä.The goal of this research was to find out the main points about starting a new business in Russia. Even though it was not a direct assignment from some company, the title for this research came from one company’s need to set up a company to Russia. That is why the research was made from Finnish company’s point of view. Different market entry strategies were left out from this study, because there are a lot of previous researches and books done around this area. Instead focus was placed on starting both, company and representation office, and looked through different types of business entities used in Russia this day. Also other things that are important to know when starting a business in Russian were taken along, for example employing personnel, finding premises, protecting company’s trade mark, and arranging safety issues. Russia is known as a country with heavy bureaucracy and this research did prove that point. There is a huge amount of forms and certificates that are needed to start a company in Russia. Number of bureaus where those forms need to be taken, in certain demanded order, is no less. Especially for Finnish person this may seem almost frightening. However, his research showed that there is help available if needed on both sides, Finland and Russia, for solving bureaucracy or other problems. Additionally to literary and Internet sources in research was used information from seminar held by Finnish-Russian Chamber of Commerce (FRCC) and inter-viewed two Russian businessmen and one Finnish sales manager

Integrated modernization of the gas-and-air system of a turbocharged diesel engine (21/21)

Improving the exploitative and environmental performance of piston engines (PICE) is an urgent task for many engineers and scientists. The article presents the results of the upgrade of a gas-and-air system of a diesel PICE, carried out through changing the turbocharging system’s configuration and modernizing the design of the admittance collector. The authors present a review of studies on the given subject and a description of the object of the research. The study was conducted on the basis of bench tests at a manufacturing plant and mathematical modeling using ACTUS program. The results of experimental studies on the main indicators of a basic and upgraded PICEs are presented. The gas exchange processes in the PICE under examination were studied in detail using mathematical modeling. For the given diesel PICE, improvement of the gas-and-air system leads to a growth in charging efficiency by 2.45-3.92%, a decrease in scavenging factor by 3.11-6.31% and a reduction of specific fuel consumption up to 3.33%. In the conclusion, new directions for increasing the efficiency of the given PICE are offered

Stationary Gas Dynamics and Heat Transfer of Turbulent Flows in Straight Pipes at Different Turbulence Intensity

The gas-dynamic and heat-exchange behaviours of air flows in gas-dynamic systems have a significant impact on the efficiency and environmental performance of most technical equipment (heat engines, power plants, heat exchangers, etc.). Therefore, it is a relevant task to obtain reliable experimental data and physical laws on the influence of cross-sectional shape and initial turbulence intensity on gas dynamics and the level of heat transfer. In this study, data were experimentally obtained on the instantaneous values of the local velocity and local heat transfer coefficients of stationary air flows in straight pipes with circular, square, and triangular cross-sections at different initial values of the turbulence intensity. The measurements were carried out with a constant temperature hot-wire anemometer, thermocouples, and pressure sensors. Based on the research results, data on the turbulence intensity and averaged local heat transfer along the length of pipes with different cross-sections were summarised. It has been established that turbulence intensity in a square pipe is up to 40% higher than in a round channel; in a triangular channel, on the contrary, it is up to 28% lower. After the air flow’s initial turbulence, the relaxation of the flow in square and triangular pipes occurs faster than in a round channel. It is found that the initial intensity of turbulence leads to an increase in the averaged local heat transfer, which is typical of all investigated pipe configurations and initial conditions

New records of the anomaly P syndrome in two water frog species (Pelophylax ridibundus and P. lessonae) in Russia

The “anomaly P” was described in Palearctic water frogs of the genus Pelophylax by Jean Rostand as complex morphological anomalies of water frogs, including polydactyly, brachymely, hind limb oedema, bone outgrowths, spikes, flexions and additional limbs in the inguinal region. In 2016, the anomaly P syndrome was rediscovered in central Russia, confirming the hypothesis concerning its wider distribution. Here, three new records of this syndrome in two species of western Palearctic water frog from Russia are described