Small Tower Research Articles

Categorizing resident evacuation behaviors within a flood-protected area

ABSTRACT Flood management due to global warming is one of the most important issues to be considered worldwide. Communicating about flood risk between government and residents is important for enhancing awareness of residents’ evacuation. However, not enough risk information is provided to residents for evacuation from floods (e.g. where, when, and how to evacuate). Therefore, an evacuation analysis linked with a time series of inundation depths was conducted in Kawajima Town, which is surrounded by a ring levee in the watershed of the Arakawa River, Japan. According to the analysis of evacuation by walking, the evacuation should be started by the time an evacuation instruction is issued to avoid getting caught in flooding before reaching shelters. Although the analysis of evacuation by car did not consider road and bridge closures, it indicated that approximately 40% of the town’s residents would likely have difficulty evacuating to even the nearest bridge or road. The central and southern part of the town was also identified as an area where a wide-area evacuation, i.e. outside the town, would be difficult if road and bridge closures were considered. The risk map identifies high-risk areas and districts in the central, southern, and southwestern parts of the town. It also indicates the need for structures for emergent use, such as small mounds or towers for evacuation starting at the breaching time (BT) in these areas. Since there is no area where all residents can evacuate at the start of breaching time, it is necessary to start evacuation to shelters immediately after the evacuation instruction is issued. Because the number of municipalities with similar problems will increase in the future in Japan, the study of evacuation plans from flood inundation for residents in Kawajima Town is expected to serve as a model case for other municipalities to consider.

Natural draft direct dry cooling system performance at various application scales under windless and windy conditions

The natural draft direct dry cooling system (NDDDCS) presents a promising alternative to conventional forced draft air-cooled condensers (ACCs) and indirect natural draft dry cooling systems, overcoming their limitations by efficiently condensing process steam directly and passively. The NDDDCS achieves superior thermal efficiencies while reducing system complexities, operational costs, and auxiliary power consumption. Potential reductions in operational expenses for the system may offset initial capital investments, resulting in lower lifetime costs. While research to date has focused on large-scale NDDDCS performance under varying wind conditions, this work addresses a critical gap by investigating the system’s scalability for various applications, including a large-scale coal-fired power plant (900 MWt, 165 m total height), a medium-scale concentrated solar power plant (CSP) (100 MWt, 65 m total height), and a small-scale water desalination plant (1 MWt, 11.5 m total height) under both windless and windy conditions. To achieve this, a steady-state 3-D computational fluid dynamics (CFD) model is developed, validated and scaled, incorporating innovative features such as an atmospheric pressure gradient and the ability to capture reversed flows through the system’s heat exchangers. Additionally, the model assesses inlet air temperature data at a per-cell resolution, enabling the ability to predict non-uniform temperature distributions in the heat exchangers, including hot-spots caused by airflow recirculation. Analysis of velocity and temperature fields across all scales reveals that recirculation effects negatively impact NDDDCS performance, particularly at the middle circumferential heat exchanger sector. The hyperbolic shape of the tower shell induces internal recirculation zones and reduces the effective flow volume. Under windy conditions, performance losses of 44%, 40%, and 40% are observed at crosswind speeds of 3 m/s, 6 m/s, and 9 m/s for small, medium, and large-scale towers, respectively. Beyond these speeds, the relationship between system performance and draft driving potential becomes non-linear due to crosswind effects dominating. Furthermore, a novel effect is identified at wind speeds of 9 m/s, 15 m/s, and 18 m/s for small, medium, and large-scale systems, respectively, where an inflection point allows for system performance recovery. This study underscores the NDDDCS’s potential as a cooling solution for modern power cycles across various scales, while highlighting the implications of scaling the system for medium- and small-scale thermal applications.

Designing an energy storage system based on water tower pumping to store the energy generated by the turbo-expander implemented in a gas pressure reduction station

In the present research, an energy recovery and storage strategy for a natural gas pressure reduction station with a capacity of 50,000 Nm3/h has been proposed. Currently, the gas pressure reduction station does not have an energy recovery system; hence, energy of high-pressure natural gas is wasted in it. For this reason, first, the energy recovery system was thermodynamically designed based on the use of a turbo-expander instead of the regulator, and the extracted energy was calculated. The results showed that 1.376 GWh electrical energy can be generated annually using the recovered energy. Then the economic analysis of the use of the proposed plan was discussed. The results of the economic analysis showed that the investment payback period for installing the turbo-expander in the considered station is 2.4 years. In the last part of the research, an energy storage system was designed to store the generated electrical energy. For this purpose, an energy storage system based on water pumping in water towers was designed. Water towers with different classes were investigated. The obtained results showed that the average energy conversion efficiency in the energy storage system varies from about 70 % for small water towers to about 74 % for large ones.

Vnútorné členenie a príslušenstvá šľachtickej kúrie na konci stredoveku (deľba kúrie v Lukavici v roku 1524)

In 1524 brothers John, George and Stephen divided the manor house (curia nobilitaris) of their father in the village Lukavica into three parts. Only the first of the brothers remained living in Lukavica and was still a lower-ranking member of the nobility. The division of the manor describes the interior spaces of the house: the black room, the old kitchen, the room behind the kitchen, the hall and the room with lighting. The house also had a cellar. In the courtyard there was a piggery, stables, barn and a chicken coop. The entrance consisted of a gate with a small tower. Another black room, a brewery, a pond and a mill belonged to the nobleman’s house. The division is exceptionally detailed and it is a unique source in the region of the Zvolen County. The charter has been preserved in a copy from the middle of the 16th century. The manor and its accessories became the subject of disputes and repeated divisions over the following generations. Female members of the family, in some cases married to non-nobles, played an important role in these disputes. The manor house in Lukavica still existed at the end of the 17th century after the change of owners. It is possible that it was subsequently converted into a farmstead, which still exists to the north of the village.

SO3/sulfuric acid mist removal in simulated flue gas: Multi-factor study based on two-film theory mass transfer process

SO3/sulfuric acid mist is a strongly irritating pollutant presented in small quantities in flue gas, which poses a major threat to the power plants operation and atmospheric environment. In this study, SO3/sulfuric acid mist at different positions and after different spraying time of the small desulfurization tower were extracted and absorbed by isopropanol solution, and the SO42- concentration was detected by barium-thorium titration. Then the SO3/sulfuric acid mist mass transfer model in desulfurization process was constructed on the basis of two-film theory to investigate the effects of different tower structures, spraying time and operating conditions on SO3/sulfuric acid mist removal in desulfurization tower. The results showed that the tower structures had the greatest influence on SO3/sulfuric acid mist removal, and the highest SO3/sulfuric acid mist removal efficiency was achieved after the spraying time of 0–20 min and at the flue gas distribution plate. Moreover, according to the results of SO3/sulfuric acid mist mass transfer model, SO3 removing process was not controlled by solid dissolution instead of by gas–liquid film turning to gas film with flue gas residence time running in the tower. The model results also showed that SO3 removing process was controlled by gas film for a very short period then turning to gas–liquid film immediately with spraying time accumulating in a specific tower position. Besides, it showed the increase of NH3 concentration and spraying flow rate promoted the SO3/sulfuric acid mist removal, and the increase of SO2 concentration and slurry temperature inhibited the SO3/sulfuric acid mist removal.

Characterizing cable-logging enterprises in Italy: production, workforce, equipment and potential for growth

ABSTRACT Interviews with 51 entrepreneurs indicated that Italian cable-yarding specialist companies are small-scale businesses with a workforce of 3 to 5 operators and an annual production of about 5000 m3 over bark. Their primary piece of equipment is a tower yarder, which relies on a support fleet consisting of adapted farm tractors and excavators. There is a clear divide between alpine and non-alpine entrepreneurs, the latter being less productive and somewhat more versatile than the former. That difference is likely dependent on the different work environment: alpine operators can rely on larger public owners, bigger softwood trees and more valuable timber products, whereas non-alpine loggers are constrained by fragmented private ownerships, smaller hardwood trees (often coppice) and less valuable firewood products. Non-alpine loggers also yard on shorter distances and use smaller towers. Further expansion of cable-logging south of the Alps could be achieved by developing new equipment capable of overcoming those limitations. In that regard, one may consider unguyed towers designed for live skyline operation.

Numerical Simulation on Temperature and Moisture Fields Around Cooling Towers Used in Mine Ventilation System

For heat rejection, small air-cooling towers are widely used in mine ventilation systems. However, the thermal efficiency of the cooling towers can be significantly affected by their geometrical arrangement and crosswind conditions. In certain ambient conditions, heated air coming from an exit of one tower can flow to intakes of other towers, which leads to a reduction in the thermal efficiency of the entire ventilation system. The aim of this study was to investigate the influence of crosswind speed and tower spacing on the temperature and moisture content of intakes of cooling towers. For this purpose, a three-dimensional CFD model of the non-isothermal turbulent flow of moist air around cooling towers is proposed. The model is based on the Reynolds-averaged Navier–Stokes equations with a standard turbulence model which are supplemented by heat transfer and moisture transport equations. The investigation of the effects of the crosswind speed and the tower spacing was carried out for two cooling towers by multiparametric numerical simulation using the CFD model. It was shown that the upstream tower protects the downstream one from the effect of the crosswind. The increase in the crosswind speed causes a rise in temperature and moisture content at the intakes of the downstream tower. The increase in the tower spacing, in general, contributes to a decrease in air temperature at the intakes of the downstream tower. However, at low crosswind speed, the heat transfer at the intakes can rise with the tower spacing due to a reduction in the protection possibilities of the upstream tower. Results of the numerical simulation of airflow around three cooling towers indicated that the increase in the number of cooling towers contributes to a rise in temperature and moisture content at the intakes.

Methane, carbon dioxide, hydrogen sulfide, and isotopic ratios of methane observations from the Permian Basin tower network

Abstract. We describe the instrumentation, calibration, and uncertainty of the network of ground-based, in situ, cavity ring down spectroscopy (CRDS) greenhouse gas (GHG) measurements deployed in the Permian Basin. The primary goal of the network is to be used in conjunction with atmospheric transport modeling to determine methane emissions of the Delaware sub-basin of the Permian Basin oil and natural gas extraction area in Texas and New Mexico. Four of the measurements are based on tall communications towers, while one is on a building on a mountain ridge, with the recent addition of a small tower at that site. Although methane (CH4) is the primary species of interest, carbon dioxide (CO2), hydrogen sulfide (H2S), and the isotopic ratio of methane (δ13CH4) are also reported for a subset of the sites. Measurements were reported following the WMO X2004A scale for CH4 and the WMO X2019 scale for CO2. CRDS instruments were calibrated for CH4 and CO2 in the laboratory prior to deployment. For H2S, data were offset-corrected using the minimum 40 min running mean value of the day, and for δ13CH4, calibrations were based on laboratory data. We describe the characteristics of the dataset with a set of illustrative analyses. Methane and carbon dioxide showed strong seasonality, with a well-defined diurnal cycle during the summer, which was opposed to the winter, when a diurnal cycle was absent. CH4 enhancements to the background, during the winter, are up to twice the summer values, which is attributed to the changes in boundary layer depth and wind speed. The largest CH4 enhancements occurred when winds blow from the center of the Delaware sub-basin, where most of the methane emissions come from. The magnitude of enhancements of CO2 did not present seasonality. H2S enhancements indicated a potential source northeast of the tower (Hobbs, New Mexico) where the inlet is installed. Isotopic ratios of methane indicated that oil and natural gas extraction is the source of local methane in the region. The hourly-averaged data, starting on 1 March 2020 and described in this paper, are archived at The Pennsylvania State University Data Commons at https://doi.org/10.26208/98y5-t941 (Monteiro et al., 2021).

Optical analysis and optimization of a beam-down receiver for advanced cycle concentrating solar thermal plants

Next generation CST plants need to move towards higher operation temperatures and advanced cycles to obtain higher thermodynamic efficiency. Beam-down receivers (BDRs) can unlock higher operation temperatures via ground-mounted receivers which use solid and gas-phase heat transfer media—as opposed to nitrate salts, which have a <600 °C limit—and avoid the pumping requirements of a conventional tower-mounted receiver. This work presents a novel method to study the optics of BDRs, which is then applied to the most promising optical design. The flux distribution in both the secondary optical element (i.e., a hyperboloid mirror in the present study) and tertiary optical element (i.e., a polygonal CPC array in the present study) were obtained to calculate their optical efficiencies for a wide range of potential geometric designs. It was found that the main limitations on geometry were the hyperboloid height and the CPC’s concentration ratio. In addition, it was found that this technology is a good option for small towers (around 50 m height) and for small, modular receivers (i.e., ∼30 MWth), noting that multiple receivers could serve a central power block. For this size, a BDR’s optical efficiency of 82.3% is obtained. It was also found that this BDR module (i.e., including both the hyperboloid and the CPC array) represents only a 2.56% (1358 m2) increase of total plant mirror area as compared to tower mounted receiver. Lastly, this design was estimated to provide overall (sun-to-electricity) efficiency of 20.3% using a sCO2 power cycle, which is comparable to conventional CST plants but with potential lower costs.

Climate resilience technology for year round vegetable production in northeastern Bangladesh

A study was carried out to investigate climate resilience vegetable production prospect using tower gardening technology during the period of July’2017 to December’2018 in low-lying areas of northeastern Bangladesh (Sylhet and Moulvibazar). Total 24 participants of DFID and EU funded Suchana program (January-December’2017) were involved in the study. Two sizes of tower (a) medium size (4.5 feet diameter and 5.0 feet height) (b) small size (3.0 feet diameter and 4.0 feet height) and two types growing media protecting material (i.e. plastic bag &amp; bamboo mat) were used separately to perform the study. To prepare the growing media (50%) soil, (40%) cow dung/compost and (10%) decomposed water hyacinth were used. Mainly two types of vegetables, climbers (i.e. bottle gourd and bitter gourd) and herbaceous (i.e. kangkong, Indian spinach, red amaranth and okra) were planted to conduct the study. The vegetable production was significantly influenced by tower size &amp; growing media protecting materials and the highest vegetable production (84.35 kg tower-1 and 42.17 t ha-1) was recorded in medium size tower with plastic bag whose sold value was BDT 1968.50 tower-1 and BDT 98.43 Lac ha-1, respectively. In addition, the lowest vegetables production (42.08 kg tower-1 and 21.04 t ha-1) was recorded in small tower with bamboo mat that’s sold value was BDT 955.92 tower-1 and BDT 45.99 Lac ha-1, respectively. Cost-benefit ratio (2.85) was recorded in medium tower and 1.73 in small tower. In disposal pattern of vegetables major portion was used for family consumption (80% and 90%), distribution (15% and 10%) and sold (5% and 0%) in medium and small tower garden, respectively. From the result it may say that both size of tower garden were technically feasible to grow vegetable in inundated situation but medium size tower made of plastic bags performed better than bamboo mat due to less nutrient loss through leaching. The study found tower gardening on medium size tower with plastic bag could be a potential and effective option for year round vegetable production in climate vulnerable communities of Bangladesh.&#x0D; Int. J. Agril. Res. Innov. Tech. 11(1): 29-36, June 2021

Classical Physics-based Renewable and Sustainable Energy Transition Concept

By many accounts, Lorentz was ahead of his time by suggesting before quantum mechanics that some disturbances, like waves, travel with particles through a vacuum without moving it. The waves associated with the Lorentz metrics are described by the Klein-Gordon equation and dispersion relation w²=c²k²+w_c². In hydromechanics, they are known as non-propagating waves and w_c is a constant called the cutoff frequency. The waves are not propagating if their frequency is below the cutoff frequency w_c. Their group and phase velocity are related by vu=c², in the infinite k limit v=u=c. A quantum object is considered as a particle moving in resonance with wave characterized by the Klein-Gordon dispersion relation with cutoff or Compton frequencyw_c=mc²/ħ. This approach brings field values (group velocity and intensity of transverse non-propagating waves) into Maxwell's equations, and antiparticles or non-propagating waves with negative group velocity into Newtonian mechanics. In classical astrophysics, matter-antimatter interactions led to the universe expansion, formation of galaxiesand sources of intense cosmic radiation. Classical field theory could play a major role in clean energy research. In particular, concentrating solar power (CSP) systems, i.e. Stirling engine (SE) or small direct-heated tower, with thermal energy storage (TES), diffuse light-utilizing photovoltaic (PV) cell and 3D-printed thermal field emission (TFE) converters will dramatically lower the cost and energy payback time of the CSP technologies. The design explores recent developments in field-effect PV cells. 3D-printed TFE panels-integrated in TES or micro-channel solar receivers. The improved performance of the TFE converter compared to photovoltaic cells at high temperatures is attributed to the simultaneous use of diffusion and ballistic electron transport to harvest both thermal and photon energy. In addition, a gas cooled water moderated reactor is explored to integrate electrical-in-nature nuclear energy into smart micro-grids. and convert the most hazardous wastes into an emission-free fuel and medical isotopes. Transmutation reactor, in which depleted uranium acts initially as an absorber and later as fuel, behaves like fast reactors, but without their difficult control problems and high fissile fuel load.

Experimental Study on the Performance of Small Solar Updraft Tower in the Climate Region

Solar updraft tower (SUT) power plant is a unique system using solar energy, which consists of three main parts: the chimney, turbine, and collector. In tropical climate conditions, especially in Malaysia, the application of solar chimney can be deemed more competitive compared to other renewable energy systems. In this study, one prototype with a dimension of 3.5 m in diameter for the collector and 5 m height for the chimney, was built in Melaka, Malaysia. Vital parameters such as temperature field, pressure, humidity, and air movement were measured using data logger and stored using non-volatile memory. The most exciting finding was that the temperature and pressure difference was significantly seen during the experiment along the day. There was a significant surge for the humidity in the morning with an average of above 95% and the ambient temperature was approximately 35 °C due to low solar radiation. The humidity kept decreasing after sunrise due to the greenhouse effect produced in the solar collector. With the collection of these critical parameters, a solar chimney power plant was adequate to function and generate power from solar radiation in a country such as Malaysia, which is based in the equatorial region. These studies are limited as the analysis focused mainly for high radiation and did not investigate efficiency during low solar radiation. The addition of heat storage underneath the collector with current techniques is another direction of research for continuous system operation, particularly during low solar radiation. It is proposed that the synthesis of these factors should be extensively explored in future studies coupled with the application of heat storage.

Influence of site and tower types on urban natural ventilation performance in high-rise high-density urban environment

This paper investigates the urban ventilation performance at the street and tower-level in the high-rise high-density urban environment of Hong Kong. By analyzing 218 residential developments and 659 residential towers from 2003 to 2013, this paper presented an innovative way of generating idealized urban forms that considers the regulatory and social-economic factors. Nine typical high-rise high-density residential urban design scenarios with different site division strategies and tower types were generated. The urban ventilation performance of these cases was studied using a validated CFD simulation technique under four different approaching wind directions. Two indices were applied to quantify the urban ventilation performance in this study, namely Wind Velocity Ratio (WVR) and Local Mean Age of Air (MAA). The results show that site and tower types have a great influence on urban ventilation. This paper concludes that extra-large sites (around 4000 square meters) have the potential of achieving the best performance in both street and urban level ventilation, while probably enduring poor indoor air quality. Therefore, a centralized tower plan without deep re-entrants is recommended for large sites. For the small (around 500 square meters) and medium (around 1000 square meters) sites that generally have poor street-level ventilation, adding service lanes can help to improve the street ventilation but may cause poor tower-level ventilation since two rows of towers are closely placed in one street block. For the small sites without service lanes, small and rectangular tower plans in one row could help to achieve better tower-level ventilation and indoor air quality potential.

Smart composite detector of orbital debris and micrometeoroids particles

The presence of space debris and micrometeoroids particles in the space environment are a serious threat for Earth orbiting spacecraft. Hypervelocity impacts (HVIs) at the typical velocities of ∼7 to 10 km/s can severely damage or destroy satellites, so that debris detection systems are necessary. In the present research work, a “smart” composite detector of orbital debris and micrometeoroids particles is proposed and developed as proof-of-concept for future space missions. The presented detector consists of two thin parallel carbon fibre reinforced plastic (CFRP) composite plates, each instrumented with three piezoelectric transducers embedded into the laminate. The developed algorithm can estimate both directions and velocities of orbital debris and micrometeoroids particles by the knowledge of: (i) impact locations on the two plates, (ii) the time differences of arrival of acoustic emissions generated by impacts and (iii) the wave velocity profile in the composite plates. The localisation of the impact events is achieved by time reversal method, while the time of arrivals are calculated using Akaike Information Criterion method. A set of experimental tests were performed to validate the proof-of-concept using a small drop tower. Impact results showed the high accuracy of the proposed algorithm in the estimation of impact locations, directions and velocities of impact objects.

Advanced non-destructive techniques for the diagnosis of historic buildings: The Loka-Hteik-Pan temple in Bagan

The archaeological site of Old Bagan, located in the centre of Myanmar, is one of the most remarkable and ancient Asian site with over three thousand monuments, scattered in an area of about 80 km2. The site was hit in 2016 by the last of a series of earthquakes. The Loka-Hteik-Pan is a hollow-core temple featured by a small elegant curvilinear tower. It was significantly damaged by the event, losing the upper part of the tower, as many other temples of the area. Emergencies like seismic events generally require quick responses and targeted solutions. When a built area is involved, damaged buildings need structural assessments with a special focus on space and time occupancy, without compromising the reliability of the results. A workflow for data acquisition and analysis is proposed, using non-destructive techniques to evaluate the materials performances and measure spatial changes over times. Deformation analysis is performed on LiDAR data, acquired prior and after the earthquake, with the goal of measuring small changes occurred in the wall surfaces. The preliminary results of the tests are presented with the purpose to provide a knowledge base, useful to guide the interventions for preserving the monument and its heritage.

Small scale solar tower coupled with micro gas turbine

This paper studies a small-scale CSP system composed of a solar tower and a recuperative air micro gas turbine (i.e. net power in the 100–200 kWe range). A code is developed to determine the optical performance of the heliostat field coupled with a secondary concentrator, while another code computes the thermal engine performance. The 832 m2 heliostat field layout is taken from a real plant, while the secondary optics is studied to maximize the optical-thermal efficiency. The selected secondary concentrator (CPC), with an aperture diameter of 0.5 m and an acceptance angle of 35° tilted of 52.5°, guarantees an overall optical efficiency of 77.9% in design conditions (Spring equinox, solar noon) and of 66.9% on yearly basis. For every Effective DNI (EDNI) and ambient temperature the turbine operation is optimized allowing to achieve a yearly solar-to-electricity efficiency of 16.3%. Summing up the cost of each component, an overall plant cost of about 2300 €/kW (peak) and a LCOE of 175 €/MWh are obtained. A sensitivity analysis on design EDNI, impacting on turbine size, is performed showing that its reduction from 700 W/m2 to 550 W/m2 allows reducing the LCOE down to 158 €/MWh, a value competitive with large-scale solar towers. The possibility of hybridization of plant (i.e. improving the gas turbine power output in selected hours, by means of biomethane or natural gas combustion) was considered to further reduce the LCOE.

Tool for Recovering after Meteorological Events Using a Real-Time REM and IoT Management Platform

This paper is the design of a Radio Environment Map (REM) with a real-time tool to sense the radiofrequency spectrum and optimally places with Surrogate Modelling and Sequential Experimental Design tools a total of 72 SDR sensors in the selected area, using LoRa and/or NB-IoT technologies for networking. It permits the regulatory body to check the correct use of the assigned spectrum and constitutes a communication alternative in case of a catastrophic event, such as a hurricane or an earthquake, where radio and TV broadcasting play an important role in keeping people informed after such meteorological event. The radiobroadcast services use large antennas and high towers, making them vulnerable to such events. Regardless of the chosen technology, the IoT monitoring network will be more robust, since it uses small antennas and lower towers, and often a given area is covered by multiple base stations. The tool can be used to deploy new services in the nonserved area (e.g., 4G in the 700 MHz band at a lower cost or using TVWS techniques to provide communications and internet connection) and optimal interference management.

Design implications for teamwork in ATC

In air traffic control (ATC), teamwork is a key component among air traffic control operators (ATCOs) to safely direct the aircraft through the sky and on the ground. To be able to design for future ATC systems, we must understand how ATCOs work together, their teamwork, and how they experience and perceive teamwork, in different ATC environments. We conducted interviews with 16 ATCOs working in four different ATC environments (en-route control, terminal area control, tower control for a small airport and tower control for a large airport in Sweden) and analysed the results in the light of the “Big Five” model of teamwork. The main contributions of this paper are to show: (1) how eight teamwork factors are differently manifested by the ATCOs in the different ATC environments, (2) that teamwork in ATC is important during routine operations, during stressful work, and during abnormal situations, and (3) that the design of the organisation, the environment, and the tools, affects teamwork and the importance of different teamwork factors.

New surface microstructure of mono-si wafer textured using wet chemical solutions for solar cell (revised paper (2))

Mono-Si textured surface covered with pyramids has been widely used in the solar cell. However, there are few reports of new microstructures instead of pyramids on Mono Si surface. By adding the special additive, we change the anisotropic texturing properties of alkaline solutions to develop a new small tower over Mono Si surface. The surface was evaluated by scanning electron microscopy, minority carrier lifetime instrument and integral reflector. The results show that this new microstructure has the minority carrier lifetime of 9.72 µs, reflectivity of 10.12% within 400–1000 nm, respectively, which are better than that of solar cell based on pyramids structure. By comparing with samples covered with pyramids, it is considered that the new microstructures are suitable for the possible applications of silicon solar cells. In addition, we also found the non-linear relationship between minority carrier lifetime and the tower size.

Kule na ulazu u Kanal sv. Ante – neodvojivi dio šibenskih fortifikacija

Velika i Mala kula na početku šibenskog Kanala sv. Ante, na današnjim rtovima Burnji i Južni turan, dio su srednjovjekovnog fortifikacijskog sustava grada zajedno s kaštelom sv. Mihovila i gradskim bedemima, čemu do sada u znanstvenoj literaturi nije posvećena dovoljna pažnja. Kule su ostale dijelom fortifikacijskog sustava Šibenika i početkom ranog novog vijeka sve do izgradnje tvrđave sv. Nikole, odnosno definitivnog rušenja kula početkom Ciparskog rata 1570. godine. Iako su građene na priličnoj udaljenosti od gotovo jednog kilometra od gradskih bedema, do izgradnje tvrđave sv. Nikole predstavljale su prvi obrambeni pojas Šibenika s morske strane. Između kula na udaljenosti od oko 140 metara nalazio se lanac koji se najvjerojatnije sastojao od povezanih drvenih trupaca što su lancu omogućavali da pluta. Teško je sa sigurnošću kazati kad su mletačke vlasti dale porušiti kule, ali se čini da je barem jedna srušena tijekom tzv. Trećeg mletačko-osmanskog rata (1537. – 1540.) kad je mletačkim posjedima u Dalmaciji prijetila velika opasnost od snažne osmanske flote. Kule su definitivno prestale biti dio fortifikacijskog sustava grada početkom Ciparskog rata 1570. godine.