Conformal Antenna Array for Millimeter-Wave Communications: Performance Evaluation

In this paper, we study the influence of the radius of a cylindrical supporting structure on radiation properties of a conformal millimeter-wave antenna array. Bent antenna array structures on cylindrical surfaces may have important applications in future mobile devices. Small radii may be needed if the antenna is printed on the edges of mobile devices and in items which human beings are wearing, such as wrist watches, bracelets and rings. The antenna under study consists of four linear series-fed arrays of four patch elements and is operating at 58.8 GHz with linear polarization. The antenna array is fabricated on polytetrafluoroethylene substrate with thickness of 0.127 mm due to its good plasticity properties and low losses. Results for both planar and conformal antenna arrays show rather good agreement between simulation and measurements. The results show that conformal antenna structures allow achieving large angular coverage and may allow beam-steering implementations if switches are used to select between different arrays around a cylindrical supporting structure.Comment: Keywords: conformal antenna, millimeter-wave communications, patch antenna array. 11 pages, 10 figures, 1 tabl

Meillä kaikilla on jotain, mikä kannattelee:nuorten kokemuksia heidän resilienssiään edistävistä tekijöistä

Tiivistelmä. Tutkimuksessa selvitetään nuorten kokemuksia siitä, millaisten asioiden he kokevat vaikuttavan heidän resilienssiinsä. Tätä selvitetään sekä yleisellä tasolla että opinnoissa selviämisen näkökulmasta. Tavoitteena on tutkia, millä tavoin tämä ilmenee ammatillisessa erityisoppilaitoksessa. Tämän lisäksi tavoitteena on löytää keinoja heidän resilienssinsä vahvistamiseksi. Resilienssillä tarkoitetaan kykyä sopeutua myönteisellä tavalla sekä palautua erilaisista tilanteista. Tutkimusaineisto kerättiin haastattelukysymysten avulla 18–23-vuotiailta opiskelijoilta erityisammattioppilaitoksessa Luovilla, keväällä 2021. Seitsemän opiskelijaa haastateltiin ja yksi opiskelija vastasi kysymyksiin kirjallisesti. Aineiston analyysimenetelmänä käytettiin aineistolähtöistä ja teoriaohjaavaa sisällönanalyysia. Tutkimuksen tulosten perusteella voitiin havaita, että nuorten selviytymistä ja resilienssiä vahvistavat 1) materiaaliset resurssit, 2) vapaa-aikaan ja hyvinvointiin liittyvät tekijät, 3) tukea antavat ja voimauttavat ihmissuhteet, 4) opintoihin liittyvät tavoitteet ja merkityksellisyyden kokemus, 5) kokemus omasta pystyvyydestä sekä 6) henkinen kasvu. Tutkimuksessa kävi ilmi, että kyseinen tutkimusjoukko tunnistaa useita itseään tukevia elementtejä ja osaa huomioida näiden asioiden merkitystä omassa elämässään. He kokivat, että heistä oli välitetty oppilaitoksessa ja he olivat saaneet monipuolista tukea sekä opintoihin että sosiaalisiin suhteisiin liittyen. He kokivat ilmapiirin oppilaitoksessa hyväksi ja oppimista edistäväksi. Monet käytetyt opetus- tai muut oppimisen tuen menetelmät olivat selkeästi merkityksellisiä. Välittävien ja luotettavien aikuisten tuen koettiin vaikuttavan jaksamiseen. Osittain tulosten perusteella oli havaittavissa, että yksilöllisten vahvuuksien tunnistamiseen ja kyvykkyyden kokemuksen lisäämiseen voisi kiinnittää vielä enemmän huomiota. Tutkimustulosten pohjalta tehtiin johtopäätelmät, että nuorten tukeminen oppilaitoksessa on ollut monella alueella hyvin onnistunutta ja näitä samoja keinoja tulee edelleen jatkaa. Tällaisia alueita ovat sosiaalisissa suhteissa tukeminen ja opiskelijoista välittäminen monella tasolla, opiskelijoiden oman vastuun esiintuominen liittyen hyvinvointiin ja jaksamiseen, opiskelijoiden omien toiveiden korostaminen opiskelun tavoitteissa sekä pystyvyyskokemusten mahdollistaminen. Näiden lisäksi vahvuuksien ja kykyjen painottaminen oppilaitoksessa on tärkeää. Tuloksia voidaan hyödyntää opetuksessa ja erityisesti nuorten vahvuuksien ja resilienssin tukemisessa.We all have something that supports us : the experiences of young people of the things that enhance their resilience. Abstract. The study examined young people’s experiences of things they feel affect their resilience. This was investigated both from a general level and from the perspective of coping in studies. The aim was to study how resilience manifests itself in a vocational special education. In addition, the goal was to find ways to strengthen their resilience. Resilience refers to the ability to adapt in a positive way and to recover from different situations. The research material was collected with interview questions from students aged 18–23 at the Luovi vocational college, in the spring of 2021. Seven students were interviewed and one student answered the questions with written answers. Data-based and theory-based content analysis was used as the method of data analysis. Based on the results of the study, it was found that the well-being and resilience of young people are strengthened by 1) material resources, 2) factors related to leisure and well-being, 3) supportive and empowering relationships, 4) goals set for studies and experience of relevance, 5) self-efficacy experiences and 6) mental growth. The study revealed that students recognized several self-supporting elements and could consider the importance of these issues in their own lives. They felt that their needs had been recognized at the school and had received a wide range of support, both in terms of studies and social relations. They felt the atmosphere in the school was good and conducive to learn. Many of the teaching or other learning support methods used were clearly relevant. Support from caring and trusted adults was found to affect coping. Partly based on the results, it was observed that even more attention could be paid to identifying individual strengths and enhancing the experience of ability. Based on the results of the research, it was concluded that many things at the institution has been done well and these methods should be continued. The methods include supporting in social relations and caring for students at many levels, highlighting students’ own responsibilities for well-being and coping, emphasizing students’ own aspirations in their learning goals, and enabling experiences of ability. In addition to these, emphasizing strengths and abilities in the educational institution is important. The results can be used in teaching and especially in supporting young people’s individual strengths and resilience

Evaluating the Assumptions of Surface Reflectance and Aerosol Type Selection Within the MODIS Aerosol Retrieval Over Land: The Problem of Dust Type Selection

Aerosol Optical Depth (AOD) and Angstrom exponent (AE) values derived with the MODIS retrieval algorithm over land (Collection 5) are compared with ground based sun photometer measurements at eleven sites spanning the globe. Although, in general, total AOD compares well at these sites (R2 values generally over 0.8), there are cases (from 2 to 67% of the measurements depending on the site) where MODIS clearly retrieves the wrong spectral dependence, and hence, an unrealistic AE value. Some of these poor AE retrievals are due to the aerosol signal being too small (total AOD<0.3) but in other cases the AOD should have been high enough to derive accurate AE. However, in these cases, MODIS indicates AE values close to 0.6 and zero fine model weighting (FMW), i.e. dust model provides the best fitting to the MODIS observed reflectance. Yet, according to evidence from the collocated sun photometer measurements and back-trajectory analyses, there should be no dust present. This indicates that the assumptions about aerosol model and surface properties made by the MODIS algorithm may have been incorrect. Here we focus on problems related to parameterization of the land-surface optical properties in the algorithm, in particular the relationship between the surface reflectance at 660 and 2130 nm

On the use of a satellite remote-sensing-based approach for determining aerosol direct radiative effect over land : a case study over China

Peer reviewe

Determination of land surface reflectance using the AATSR dual-view capability

Peer reviewe

Aerosol retrieval experiments in the ESA Aerosol_cci project

Within the ESA Climate Change Initiative (CCI) project Aerosol_cci (2010–2013), algorithms for the production of long-term total column aerosol optical depth (AOD) datasets from European Earth Observation sensors are developed. Starting with eight existing pre-cursor algorithms three analysis steps are conducted to improve and qualify the algorithms: (1) a series of experiments applied to one month of global data to understand several major sensitivities to assumptions needed due to the ill-posed nature of the underlying inversion problem, (2) a round robin exercise of "best" versions of each of these algorithms (defined using the step 1 outcome) applied to four months of global data to identify mature algorithms, and (3) a comprehensive validation exercise applied to one complete year of global data produced by the algorithms selected as mature based on the round robin exercise. The algorithms tested included four using AATSR, three using MERIS and one using PARASOL. This paper summarizes the first step. Three experiments were conducted to assess the potential impact of major assumptions in the various aerosol retrieval algorithms. In the first experiment a common set of four aerosol components was used to provide all algorithms with the same assumptions. The second experiment introduced an aerosol property climatology, derived from a combination of model and sun photometer observations, as a priori information in the retrievals on the occurrence of the common aerosol components. The third experiment assessed the impact of using a common nadir cloud mask for AATSR and MERIS algorithms in order to characterize the sensitivity to remaining cloud contamination in the retrievals against the baseline dataset versions. The impact of the algorithm changes was assessed for one month (September 2008) of data: qualitatively by inspection of monthly mean AOD maps and quantitatively by comparing daily gridded satellite data against daily averaged AERONET sun photometer observations for the different versions of each algorithm globally (land and coastal) and for three regions with different aerosol regimes. The analysis allowed for an assessment of sensitivities of all algorithms, which helped define the best algorithm versions for the subsequent round robin exercise; all algorithms (except for MERIS) showed some, in parts significant, improvement. In particular, using common aerosol components and partly also a priori aerosol-type climatology is beneficial. On the other hand the use of an AATSR-based common cloud mask meant a clear improvement (though with significant reduction of coverage) for the MERIS standard product, but not for the algorithms using AATSR. It is noted that all these observations are mostly consistent for all five analyses (global land, global coastal, three regional), which can be understood well, since the set of aerosol components defined in Sect. 3.1 was explicitly designed to cover different global aerosol regimes (with low and high absorption fine mode, sea salt and dust)

In situ, satellite measurement and model evidence on the dominant regional contribution to fine particulate matter levels in the Paris megacity

A detailed characterization of air quality in the megacity of Paris (France) during two 1-month intensive campaigns and from additional 1-year observations revealed that about 70 % of the urban background fine particulate matter (PM) is transported on average into the megacity from upwind regions. This dominant influence of regional sources was confirmed by in situ measurements during short intensive and longer-term campaigns, aerosol optical depth (AOD) measurements from ENVISAT, and modeling results from PMCAMx and CHIMERE chemistry transport models. While advection of sulfate is well documented for other megacities, there was surprisingly high contribution from long-range transport for both nitrate and organic aerosol. The origin of organic PM was investigated by comprehensive analysis of aerosol mass spectrometer (AMS), radiocarbon and tracer measurements during two intensive campaigns. Primary fossil fuel combustion emissions constituted less than 20 % in winter and 40 % in summer of carbonaceous fine PM, unexpectedly small for a megacity. Cooking activities and, during winter, residential wood burning are the major primary organic PM sources. This analysis suggests that the major part of secondary organic aerosol is of modern origin, i.e., from biogenic precursors and from wood burning. Black carbon concentrations are on the lower end of values encountered in megacities worldwide, but still represent an issue for air quality. These comparatively low air pollution levels are due to a combination of low emissions per inhabitant, flat terrain, and a meteorology that is in general not conducive to local pollution build-up. This revised picture of a megacity only being partially responsible for its own average and peak PM levels has important implications for air pollution regulation policies

In situ, satellite measurement and model evidence on the dominant regional contribution to fine particulate matter levels in the Paris megacity

International audiencePublished by Copernicus Publications on behalf of the European Geosciences Union. 9578 M. Beekmann et al.: Evidence for a dominant regional contribution to fine particulate matter levels Abstract. A detailed characterization of air quality in the megacity of Paris (France) during two 1-month intensive campaigns and from additional 1-year observations revealed that about 70 % of the urban background fine particulate matter (PM) is transported on average into the megacity from upwind regions. This dominant influence of regional sources was confirmed by in situ measurements during short intensive and longer-term campaigns, aerosol optical depth (AOD) measurements from ENVISAT, and modeling results from PMCAMx and CHIMERE chemistry transport models. While advection of sulfate is well documented for other megacities, there was surprisingly high contribution from long-range transport for both nitrate and organic aerosol. The origin of organic PM was investigated by comprehensive analysis of aerosol mass spectrometer (AMS), radio-carbon and tracer measurements during two intensive campaigns. Primary fossil fuel combustion emissions constituted less than 20 % in winter and 40 % in summer of carbonaceous fine PM, unexpectedly small for a megacity. Cooking activities and, during winter, residential wood burning are the major primary organic PM sources. This analysis suggests that the major part of secondary organic aerosol is of modern origin , i.e., from biogenic precursors and from wood burning. Black carbon concentrations are on the lower end of values encountered in megacities worldwide, but still represent an issue for air quality. These comparatively low air pollution levels are due to a combination of low emissions per inhabitant , flat terrain, and a meteorology that is in general not conducive to local pollution build-up. This revised picture of a megacity only being partially responsible for its own average and peak PM levels has important implications for air pollution regulation policies