Multi-Atomic Mirror for Perfect Reflection of Single Photons in A Wide Band of Frequency

A resonant two level atom doped in one dimensional waveguide behaves as a mirror, but this single-atom "mirror" can only reflect single photon perfectly at a specific frequency. For a one dimensional coupled-resonator waveguide, we propose to extend the perfect reflection region from a specific frequency to a wide band by placing many atoms individually in the resonators in a finite coordinate region of the waveguide. Such a doped resonator array promises us to control the propagation of a practical photon wave packet with certain momentum distribution instead of a single photon, which is ideally represented by a plane wave with specific momentum. The studies based on the discrete-coordinate scattering theory display that such hybrid structure indeed provides a near-perfect reflection for single photon in a wide band. We also calculated photon group velocity distribution, which shows that the perfect reflection with wide band exactly corresponds to the stopping light region.Comment: 8 pages, 10 figure

Energy expenditure in workers mounting plastic and metallic water and sewage tubes

Energetska potrošnja montera plastičnih i metalnih cijevi vanjskog vodovoda i kanalizacije iznosi za osmosatno radno vrijeme više od 9500 kJ, a za čitav dan i više od 17 000 kJ. Za pojedine radnje utroši se i više od 45 kJ/min. Ako se uzme u obzir težak položaj pri radu te izloženost promjenjljivim klimatskim prilikama kao i opterećenje srčanožilnog sustava, taj se rad može uvrstiti u težak fizički rad.The mounting of plastic and metallic water and sewage tubes is the type of work that requires a very high energy expenditure: 45 kJ/min, 9631 kJ for eight working hours and about 17 000 kJ for a working day. Working conditions involve a very demanding working posture, carrying of heavy loads\u27 and poor weather conditions. The work is considered to be very heavy physical work

MECHANIZATION COSTS IN FRUIT PRODUCTION

Suvremena voćarska proizvodnja zahtijeva ulaganja u specijalizirane strojeve koja se kreću od oko 327 do gotovo 397 tisuća kuna, što čini od 33,65 do 39,12% ukupnih ulaganja u preporučene, ekonomski održive modele voćarske proizvodnje u našim uvjetima (3-5 ha). Udio mehanizacije u ukupnim troškovima rada po voćnim vrstama je od 10,70 do 16,29%, a u ukupnim satima rada je udio mehanizacije od 8,17 do 14,23%. Cijene sata rada mehanizacije u voćnjacima od 1 ha su od 300,54 do 399,76 kuna, dok su cijene za voćnjak površine 5 ha od 101,04 do 120,89 kuna. Ukupni troškovi mehanizacije su za voćnjak od 1 ha od 24.784 do 37.289 kuna, dok su isti troškovi za voćnjak od 5 ha od 18.719 do 26.835 kuna. Kako se s porastom veličine voćnjaka značajno smanjuju troškovi rada mehanizacije, uočljivo je povećanje koeficijenta parcijalne ekonomičnosti mehanizacije za preko 3 puta (od 3,5 do 3,8 puta) kod površine od 5 ha u odnosu na voćnjake površine 1 ha. Pokazatelji proizvodnosti rada također su od 10,2 do 17,6% veći na većim površinama.The modern fruit-growing production requires investments in specialized mechanization varying from 327,000 to 397,000 kn, which makes from 33.65 to 39.12 % of total investments in recommended, economy sustainable models of fruit-growing production in our conditions (3-5 ha). Mechanization share in total work cost is from 10.70 to 16.29 %, and in the total working hours from 8.17 to 14.23 %. The prices of working hour for mechanization in 1 ha orchards are from 300.54 to 399.76 kn, while the same prices for the 5 ha orchards are from 101.04 to 120.89 kn. The total mechanization cost for 1 ha orchard is from 24,784 to 37,289 kn, while the cost for the 5 ha orchard is from 18,719 t0 26,835 kn. With increasing orchard size the mechanization costs decrease, and mechanization partial economy coefficient increases more than 3 times (from 3.5 to 3.8 times) for the 5 ha orchard in comparison with 1 ha orchard size. Work efficiency indicators are from 10.2 to 17.6 % higher for bigger areas

Energy expenditure in female workers in a textile factory

Autori su ispitivali energetske rashode radnica na tri radna mjesta, i to: šivanje električnim strojem, krojenje električnom pilom i rad na tkalačkom stroju za izradu vrpce. Ispitivanja su vršena standardnim metodama, određivanjem energetskih ekvivalenata za pojedine specifične radnje, izradom vremenskih tablica i preračunavanjem utrošenih kalorija po pojedinim radnim satima. Utrošeno radno vrijeme podijeljeno je na djelatnosti A, B i C. A = rad, osnovni za radno mjesto, B = priprema za izvršavanje osnovnog rada i C = odmor spontani i službeni. Energetska rashodi radnica u tekstilnoj industriji pokazuju velike razlike (do 500 kal.) po pojedinim radnim mjestima. Taj podatak omogućava da se i u ovakvim pogonima lake industrije izvrši diferencijacija radnih mjesta po njihovoj energetskoj opterećenosti. Osim toga ističu potrebu da se ispita mogućnost poboljšanja samog rada, kako bi se uz manji energetski utrošak mogao postići isti radni efekt.The authors have studied the problem of energy expenditure in female workers in a textile factory, by using standard methods. Data evaluated so far show that there is a great difference in energy expenditure for different works in this factory. lt is possible to differentiate the heaviness of work done in this industry, and it is necessary to investigate what should be done to reduce the energy expenditure to a lower level

Energy expenditure in textile workers

Određivani su energetski ekvivalenti za pojedine aktivnosti u tekstilnoj industriji. Ispitivanje je izvršeno kod 17 radnika i radnika poduzeća »Nada Dimić« u Zagrebu. Ukupno je ispitano 80 uzoraka izdahnutog zraka za devet aktivnosti specifičnih za takvo poduzeće. Analiza izdahnutog zraka vršena je metodom po Scholanderu. Dobiveni energetski ekvivalenti pokazuju da je raspon kalorija koje se troše za pojedine radnje dosta velik, pa da u prosjeku varira od 1,56 do 5,63 kal/min, ali se većina radova nalazi na donjoj granici rashoda.The examination of energy expenditure requirement was carried out in a textile factory in Zagreb. 17 workers, women and men, were examined by a Franz-Müller respirometer. Expired air samples were taken and analysed after Scholander. The results shown in calories per minute include values for basal metabolism. The energy expenditure was high only in few cases; in all others the values were very low, corresponding to the values obtained by other authors