Passive Means Research Articles

Overshoot temperature control on evaporator wall of loop heat pipe for space vehicle thermal control through bypass line under high thermal load

• The thermal performance of the heat pipe was able to be enhanced by the bypass line. • The thermal performance was significantly enhanced by the bypass line. • Bypass line is a passive means for start-up thermal performance control of loop heat pipe. This paper presents the experimental results of controlling an evaporator wall temperature overshoot problem under a high thermal load by applying a bypass line to the loop heat pipe (LHP). To solve the overshoot problem during the LHP start-up, any nucleation bubbles generated on the wick surface should be removed from the vapor channel as soon as possible. In special cases, a serious evaporator wall temperature overshoot problem at high thermal loads can cause start-up failure. The LHP must be operated stably within an appropriate temperature range during start-up because any sudden rise in the evaporator wall temperature may cause serious damage to the temperature control target. To control the evaporator wall temperature overshoot of the LHP with a flat evaporator and sintered metal wick, a bypass line was installed between the evaporator and the liquid reservoir. The bypass line was integrated into the LHP using a sintered metal wick and flat evaporator, of dimensions (width and length) 40 × 50 mm. The body of the LHP was made of stainless steel, and distilled water was used as the working fluid. The vapor generated in the evaporator was supplied to the vapor transport tube through inverted axial trapezoidal grooves. The inner diameters of the liquid and vapor transport tubes were 2 mm and 4 mm, respectively, and both tubes were 0.5 m long. The input thermal load ranged up to 270 W for a coolant temperature of 10°C. The LHP was aligned at a favorite tilt angle of 15°, where an evaporator wall temperature overshoot was observed. The experimental results demonstrated the ability of the bypass line to effectively control the evaporator wall temperature overshoot during start-up under high thermal loads.

스페인어 ‘ser’ 수동 구문에 관한 고찰

The verb SER in Spanish has been defined as a copulative verb and corresponds to a verb that derives a attributive sentence. In these constructions, the verb SER is understood as an syntathe subject and the attribute as a conjunction and expresses the Tense features. The verb SER is also used in passive phrases and these constructions is semantically and syntactically different from the attributive sentence. In this study, we intend to analyze the passive syntax with SER.
 In this study, the syntactic characteristics of the passive constructions with SER in Spanish will be reviewed, and previous analyses of these constructions will be considered. Based on this considerations, we will suppose that the passive meaning is based on the Event features of the verb (Past Participle). And it is assumed that these Event features are derived from the Lexicon. In our analysis, these passive constructions are derived from Lexical-Syntax (Harley 1995).

A morphosyntactic and morphosemantic analysis of the Malay fear lexeme

Abstract For Malay, when no contextual clues are given, a lexical form can be confusing because sometimes it can have more than one meaning. We postulated that most confusing meanings can be disambiguated through observing their morphosyntactic and morphosemantic structures. We used corpus data and analyzed the possible features of takut ‘fear’ that can help decide which form of takut in Malay to choose. If a default lexical verb meaning is intended (i.e., the original meaning), the feature [Experiencer-(Stimulus)] is needed and the takut (v) form is used. If a causative meaning is intended, the men-(t)akut-kan form is used. If a passive meaning is intended, there are some possibilities, as the choice could depend on the syntax of the passive form, such as whether the [Experiencer] is a first- or second-person pronoun (e.g., benda itu saya takut-i ‘the thing feared by me’) or other pronouns (e.g., benda itu paling di-takut-i oleh-nya ‘that thing feared most by him/her’) or whether an adversative meaning is intended ([ke- -an] form). We propose that both the morphosyntactic and morphosemantic structures of takut need to be considered to better understand the use of the different meanings of Malay derived and inflected forms.

Space-filling single square and square fractal grids induced turbulence: Reynolds stress model parameters-optimization

The employment of grid-induced turbulent flow structures as a passive means of augmenting solid-fluid heat transfer is receiving considerable attention, especially in HVAC applications. However, there presently exists a gap in simulation approaches, where industry-accessible CFD packages are unable to accurately express crucial second-order turbulent flow statistics generated by space-filling single square grids (SSGs) and square fractal grids (SFGs). The present study reports a successful application of a revised Reynolds Stress Model (RSM), which accurately replicates the streamwise distributions of centerline mean flow velocity and turbulence intensity in the lee of one SSG (operating under three different flow Reynolds number ReDh) and five geometrically different SFG test cases after undergoing Nelder-Mead downhill simplex optimization of key RSM kernel parameters. The optimized RSM presents a disagreement of, at worst, 4.30% and 9.98%, respectively against experimental hot-wire anemometry measurements of first-order and second-order statistics, and is the first known instance of the RSM being validated for turbulence intensity predictions of SSG- and SFG-induced turbulence. Examination of RSM parameters reveals that the pre-factors for the rates of turbulence dissipation production and destruction (C1,ε and C2,ε) hold greatest effect on simulation accuracy, with additional optimization of the turbulent viscosity pre-factor (Cμ) required for SFG cases. This is attributed to the effect of enhanced turbulent transport due to the cascading and multiscale nature of SFG turbulence, which insofar could not be replicated by Reynolds-Averaged Navier-Stokes (RANS) models. The values of optimized C1,ε, C2,ε, and Cμ range between 1.057 to 1.697, 2.226 to 2.556, and 0.17 to 2.27, respectively. This leads to the largest deviation of −26.6%, 33.1%, and 200% for C1,ε, C2,ε, and Cμ, respectively, when compared to their corresponding default values. With regards to the sensitivity of this parameter set on grid design, it is shown that the grid's fractal iteration number N and thickness ratio tr have greatest influence on the variation of C1,ε, C2,ε, and Cμ, while the effect of ReDh is insignificant. Overall, this study presents an alternative approach to capture the anisotropic and inhomogeneous nature of SSG- and SFG-induced turbulence for industrial heat-transfer applications via an accessible RANS package, which was previously constrained to expensive DNS and LES studies.

An interactive design framework for large-scale public buildings based on comfort and carbon abatement

Large-scale public buildings usually use active means to improve indoor thermal comfort, such as cooling and heating by centralized air conditioning, which can increase building carbon emissions. It is urgent to balance the comfort and carbon abatement. Passive means have the potential to reduce building carbon emissions, such as the atrium. However, the effect of atrium on comfort and carbon abatement is influenced by outdoor environment, which is ignored in the traditional research. Therefore, this paper proposes an interactive design framework for outdoor environmental paving (O-EP) and indoor ventilated atrium skylight orientation (I-VA). Taking a large-scale public building in Xinghua city as an example, three common outdoor pavement forms (hard paving, shrub greenery, water bodies) and five building atrium skylight orientations (0°, 45°, 90°, 135°, 180°) are selected. Carbon abatement rate and adaptive predicted mean vote (aPMV) are used as evaluation indicators for carbon abatement and comfort respectively. The couple of O-EP and I-VA on building carbon abatement and comfort is obtained by analysis of correlation and ANOVA. Numerical simulations are validated by experimental data. The results show that (1) different combinations vary significantly, annual carbon abatement rates and comfort are 17.5% and 15% higher for the combination of water bodies of O-EP and 135° of I-VA than for the worst; (2) correlation analysis shows that carbon abatement rate is correlated with O-EP at the 0.01 level and not with I-VA; (3) in the warmer seasons, comfort is correlated with O-EP at the 0.01 level and not with I-VA; in the cooler seasons, comfort is correlated with I-VA at the 0.01 level and not with O-EP. This study can provide an important reference for design strategies for low carbon development and green buildings.

Experimental investigation of the effect of inward and outward propeller rotation on single blade and propeller loads

This paper is a sequel of the experimental investigation presented in Ortolani and Dubbioso (2019a) that addressed the single blade and propeller loads during the steady phase of the turning circle. In particular, the effect of inward and outward propeller sense of revolution on the propulsive performance has been investigated for a twin screw ship model equipped with a novel set-up pursued for the measurements of the single blade loads. On the basis of previous numerical investigations (Muscari et al., 2017; Dubbioso et al., 2022), the propeller sense of revolution should be evaluated as a passive mean to mitigate the amplification of the mean or fluctuating component of the blade loads and associated side effects (i.e., noise) caused by blade–wake interactions that occur during maneuvering conditions. The understanding and the accurate quantification of propeller loads, in these realistic operative scenario, is pivotal to design low emission and comfortable ships, fulfilling the requirements of safety and continuity of operations at sea. The analysis is carried out revisiting the investigation in Ortolani and Dubbioso (2019a) for the approach speed at FN=0.26 and a large set of rudder angles that span from moderate to tight maneuvers.

Binaya Entegre Fotovoltaik Sistemli Bir Güneş Evinde Enerji Analizi

Increased energy demand and fossil fuel usage of the world has led to the search for new and clean energy production methods. Renewable energy sources are developing and emerging options for energy production methods. Sun is the most accessible and stable renewable energy source. There are several methods to produce energy from the sun. The building-integrated photovoltaic (BIPV) system is a well-known method for generating electricity by using solar cells to transform the energy from the sun into electricity. BIPVs are a new technique to reduce energy consumption from fossil fuels. Passive solar houses mean that the energy demand of the living space is met with the usage of solar energy for the heating and cooling demand of the living space. In this study, an existing house, located in Istanbul, is modeled and covered with photovoltaics with the help of a computer program and the amount of energy produced with the aid of these photovoltaics is presented. The analysis demonstrates that the yearly average amount of daily electricity production is varied between 1.05 kWh as the minimum value and 19.7 kWh as the maximum value for all facades. The yearly average amount of monthly electricity production is varied between 31.8 kWh as the minimum value and 599 kWh as the maximum value for all facades.

The Chinese character you (有): A functional approach

Based on the Cardiff Grammar – one model of Systemic Functional Linguistics – we investigated the uses of the Chinese character you (有), aiming to specify its semantic and syntactic functions in different contexts. Our study is guided by three functional linguistic description principles: (i) language is multifunctional; (ii) meaning is primary while form realises meaning; and (iii) different strands of meaning are realised by a single syntactic structure. The findings show that you (有) expounds the Predicator element in the clause when it expresses possession, existence, occurrence/appearance, or quantity/degree; the Predicator Extension element when it completes the experiential meaning of the Predicator; the Operator element when it expresses the interpersonal or emphatic meaning; the Auxiliary element when it expresses the temporal meaning; the predicator of the prepositional phrase when it expresses the passive or comparative meaning; and the determiner of the nominal group when it expresses the partitive meaning. The quasi-fixed phrases containing you (有) should be taken as a whole, and it performs different semantic and syntactic functions.

Ice nucleation on silicone rubber surfaces differing in roughness parameters and wettability: Experimental investigation and machine learning–based predictions

Superhydrophobic surfaces serving as icephobic surfaces are a passive means of limiting the icing of surfaces. Ice nucleation time depends on not only liquid properties and environmental conditions but also surface features; however, it is challenging to investigate ice nucleation time and the influencing parameters simultaneously. This manuscript presents two approaches, experimental testing and machine learning, to study ice nucleation time on exposed surfaces. Hydrophobic/superhydrophobic silicone rubber surfaces were fabricated, and these surfaces varied in their wettability and roughness parameters. Superhydrophobic surfaces characterized by a higher arithmetic average, root mean squared, ten-point height, maximum height of the profile, and a Gaussian roughness distribution—skewness near 0—had longer ice nucleation times. We then used neural networks to model icephobicity in relation to ice nucleation time. The predicted ice nucleation time of the model, trained using some of the experimental results, demonstrated a good agreement with the experimental outcomes. Furthermore, this machine learning approach determined the relative importance of roughness parameters, surface wettability, temperature, and droplet volume in determining surface icephobicity. The proposed approach provides a starting point for studying heterogeneous ice nucleation prediction through an understanding of the key parameters required to optimize the icephobic behavior of superhydrophobic surfaces.

Effect of sampling duration on culturable and viable bioaerosol determination when using Rutgers Electrostatic Passive Sampler (REPS)

Rutgers Electrostatic Passive Sampler (REPS) is a passive bioaerosol sampler composed of a permanently polarized polyvinylidene fluoride (PVDF) film wound into a 3D printed film holder. In order to investigate the effect of sampling duration on its performance, REPS was deployed in an indoor and outdoor location in Spring and Fall over continuing sampling periods ranging from 24 h to 21 days. Reference concentrations were determined by an active, culture-based sampler twice daily. REPS samples were analyzed for culturable bacteria and fungi as well as adenosine triphosphate (ATP) activity. The number of culture forming units (CFU) determined by REPS exhibited strong and positive correlations with sampling duration for culturable bacteria (Pearson r > 0.899, p < 0.05) and fungi (r > 0.902, p < 0.05) for both test locations. Similar results were observed for ATP activity in outdoor samples (r > 0.844, p < 0.05). REPS showed an equivalent flow rate (Qeq) as high as 4.86 ± 4.90 L/min when sampling bacteria outdoors. When sampling bacteria indoors, the Qeq was lower: 0.37 ± 0.78 L/min. When sampling fungi, the Qeq outdoors was also higher than that indoors. Overall, the study demonstrated that REPS is able to effectively capture airborne culturable bacteria and fungi by passive means of collection in indoor and outdoor environments while maintaining bioaerosol culturability for over 21 days of continuous sampling. Further studies will explore methods to improve the sample detection limit by using different sample concentration techniques as well as the sampler's integration with the next-generation sequencing techniques.

Preliminary investigation on the switching time of a photovoltaic solar-assisted heat-pump/heat-pipe hybrid system

Integrating the passive and active two-phase heat transfer means (gravity-assisted heat pipe and heat pump) in PV/T applications can solve the freezing and corroding problems associated with the water-based PV/T collectors. However, the former fails to meet the temperature demands in unfavorable weather conditions while the latter wastes solar resources in favorable weather conditions. Integrating these two could ensure flexible operation. However, the switching time of the passive and active modes was rarely reported. In the present study, a hybrid PV/T collector/evaporator which integrated the evaporation section of the heat pipe and the refrigerant pipe of the heat pump was designed and manufactured. A hybrid system that can alternatively operate in passive and active operating mode was proposed and constructed. Furthermore, a numerical model which employs a temperature transfer matrix to couple the two operating modes is developed. Based on the validated model, the switching times of the hybrid system are revealed respectively based on the criteria of overall thermal efficiency and overall exergy efficiency. In particular, the results of the two modes operated individually are also compared and discussed. The results indicate that the hybrid system respectively needs to switch two times (from active to passive and then to active) and one time (from passive to active) with respect to overall thermal efficiency and overall exergy efficiency; the deserted mode is always inferior to that it operated individually because the initialization values deviate its normal operating pattern. Comparatively speaking, the net yields show that the hybrid system finishes a straight and narrow performance and can well balance the water temperature demand and the energy saving no matter what the switching index is; meanwhile, the switching based overall exergy efficiency is more preferred because higher net yields both in heat and electricity can be completed.

Strategy for sustainable urban revitalization in a heritage tourist city with a Sub-humid Temperate climate

The environmental quality of urban public and tourist spaces affect the development of the activities of the large number of users in heritage cities, where the concept of sustainability continues to be one of the main interests for researchers around the world. Nowadays, numerous indices have been developed to determine the liveability of urban spaces; however, there are localities that, due to their topographical characteristics, tourist and social activities require methods to generate revitalisation strategies according to their characteristics. In this study, an exploratory longitudinal method was used in a central street of a world heritage city with a temperate sub-humid climate as a case study, with the objective of favouring, by passive means, thermal habitability conditions in a heritage urban space focused on promoting pedestrian mobility. As a result, an urban revitalisation strategy for the benefit of society and tourists in heritage cities was obtained to strengthen sustainable urban mobility strategies.

Trolli se ei ole poika leikki jos mie tartuttelen: frekventatiivijohdoksen kehittyminen adversatiiviseksi passiiviksi kveenissä pohjoissaamen kielikontaktin seurauksena

Derivatives ending in ttele are used with a passive meaning in the Kven dialects of Porsangerand Nordreisa. This use is a result of language contact with Sami. As in the Sami model ofadversative passive, these Kven passive derivatives express an unfavorable event. They areused with a subject argument which has a semantic role as a patient or experiencer andan agent expressed in the allative case. However, not many verbs have gone through thissemantic change. This semantic change illustrates innovative language use among bilinguals.Both second language learners, such as those described by Siitonen (1999) but also bilingualsinterpret linguistic phenomena they encounter in one language based on the knowledge oflanguages they already know. However, while multilinguals create innovations, only thoseinnovations that are accepted by the entire speech community become permanent.

On the Unmarked Passivized Unergative Construction in Mandarin

This paper introduces a particular construction named the unmarked passivized uneragtive construction (UPUC). The aim of this paper is to explore the underlying structure of UPUC from generative syntax perspective. In this construction, the subject is an Affectee, affected by the following VO sequence. The VO sequence denotes a passive meaning. In the second part, this paper summarizes the unique grammatical properties of UPUC, then points out that the UPUC are a benefit construction and the Affectee has the inalienable possessive relation with the Theme. Then the paper analyzes the derivational process of UPUC.

Semantics of the Chinese passive construction with retained object

Abstract The Chinese Passive Construction with Retained Object (CPCRO) has aroused extensive attention from scholars especially advocators of Generative Grammar due to its syntactic idiosyncrasy. Previous researches primarily concerned with such syntactic idiosyncrasy concentrate on issues of its syntactic derivation but fail to provide an empirically responsible and consensual explanation for all its instantiations. This paper initiates a new perspective by focusing on its semantics on the basis of Construction Grammar. It is argued that CPCRO is a construction with its constructional meaning characterized by a causative meaning that profiles the causee’s change. This passive causative meaning is elaborated by three verb-class-specific semantic variants, i.e., the passive cause-motion variant associated with motion verbs or verbs entailing motion and specifying the causee’s change of location, the passive cause-result variant associated with verbs of making or creating and specifying the causee’s change of state, and the passive cause-receive/lose variant associated with ditransitive verbs or verbs with the potential of taking double objects and specifying the causee’s change of possession. They are structured into a polysemy network in the sense that the passive cause-result variant is metaphorically extended from the passive cause-motion variant, whereas the passive cause-receive/lose variant encoding the object-dual-based conceptualization of Event Structure directly relates to the passive cause-motion variant which encodes the location-dual-based conceptualization, and indirectly to the passive cause-result variant which preserves the location-dual-based conceptualization due to the invariance principle of metaphorical mapping, through profile shift.

Natural convection compound heat transfer enhancement by discrete rings and the chimney effect in a vertical cylinder

Natural convection is an indispensable heat transfer process considered in the design of advanced autonomous nuclear reactors. The renaissance of inherently safe micro nuclear reactors calls for increased post shut down heat rejection rates by passive means. This study numerically investigated heat transfer enhancement in a heated cylinder by discrete rings and the chimney effect. Five equally spaced rings of varying thicknesses and heights were fitted in the heated channel to effect enhancement by flow interruption. The chimney effect was studied by appending adiabatic chimney extensions of different heights, giving rise to extension ratios of 1.5, 1.6, 1.65, and 1.75. Compound enhancement was achieved by attaching chimney extensions to a ringed channel. Nusselt number ratios, mass flow rates, temperature, and velocity profiles were presented. The results showed that compound heat transfer enhancement could increase Nusselt numbers by between 44 and 54% and lower temperatures by over 30% depending on the chimney height. Furthermore, very short chimney heights would be required in the compound setup in comparison to the tall chimneys in the chimney-only cases, for the same target heat transfer rates. The resulting compactness could greatly influence the design of very small reactors and contribute to improvements of other air-cooled passive systems.

Unique Derivative Affixes In Simalungun Language (Morphosyntax Study)

Unique derivative affixes were focused on the morphosyntax process. This study was an interdisciplinary subject in linguistics. The affixations had a function as a form of word class or meaning. The affixations in Indonesian consconsist3 types, namely prefixes, suffixes, and confixes. This study explained the processes of the unique derivative affixes in the Batak Simalungun Language. The research method used the meant that this discussed the processes of morphology and then it was made in the sentences so that the morphological process was early and more completely in the linguistics. This study used the descriptive qualitative method by using the library (documents in the corpus) to interview a few native speakers who live in Batak Simalungun areas to get the data morals. Batak Simalungun Language affixes were prefixes, confixes, and suffixes. There were three prefixes : pa- , si-, ma- (mar), three confixes: par- (pa-)….-on, ha- ... -on/an, masi- . .. –an, and the last is only one suffix; -on. The derivative affixes in Batak Simalungun which the native speaker always expressed in the daily conversation, were so nwereral processes so t the other speakers did not realize that the word had got the affixations. There are two unique derivative affixiations on the suffix –on which had the passive meaning which had the prefix and the repetition prefix which the two first letters are repeated such as sapuh be sasapu. The position of affixation was a suffix, but the meaning was a prefix in passive voice meaning.

Wildfire Smoke Observations in the Western United States from the Airborne Wyoming Cloud Lidar during the BB-FLUX Project. Part II: Vertical Structure and Plume Injection Height

Abstract The western U.S. wildfire smoke plumes observed by the upward-pointing Wyoming Cloud Lidar (WCL) during the Biomass Burning Fluxes of Trace Gases and Aerosols (BB-FLUX) project are investigated in a two-part paper. Part II here presents the reconstructed vertical structures of seven plumes from airborne WCL measurements. The vertical structures evident in the fire plume cross sections, supported by in situ measurements, showed that the fire plumes had distinct macrophysical and microphysical properties, which are closely related to the plume transport, fire emission intensity, and thermodynamic structure in the boundary layer. All plumes had an injection layer between 2.8 and 4.0 km above mean sea level, which is generally below the identified boundary layer top height. Plumes that transported upward out of the boundary layer, such as the Rabbit Foot and Pole Creek fires, formed a higher plume at around 5.5 km. The largest and highest Pole Creek fire plume was transported farthest and was sampled by University of Wyoming King Air aircraft at 170 km, or 2.3 h, downwind. It was associated with the warmest, driest, deepest boundary layer and the highest wind speed and turbulence. The Watson Creek fire plume intensified in the afternoon with stronger CO emission and larger smoke plume height than in the morning, indicating a fire diurnal cycle, but some fire plumes did not intensify in the afternoon. There were pockets of relatively large irregular aerosol particles at the tops of plumes from active fires. In less-active fire plumes, the WCL depolarization ratio and passive cavity aerosol spectrometer probe mass mean diameter maximized at a height that was low in the plume.

Sustainable urban development. Cuban challenges

ABSTRACT This contribution starts with the evolution of the main theoretical approaches through the last thirty years and some key principles for urban sustainability, followed by reflections about sustainable development in Cuba as well as challenges to improve it in urban areas, and closing with some final reflections. Approaches about the sustainable city have been changing during the last three decades, but to be sustainable, a city should be holistically planned in a participatory way, taking as much advantage as possible of the urban land and guaranteeing appropriate domestic environment, by passive energy means. Advanced concepts of integral and sustainable development are not yet applied to the city in Cuba, as there is not enough awareness about its importance for economic and social development. Priorities focus on social services and not enough on housing and habitat. Changing these approaches is one of the first challenges

Fouling of mammalian hair fibres exposed to a titanium dioxide colloidal suspension.

Fouling of surfaces in prolonged contact with liquid often leads to detrimental alteration of material properties and performance. A wide range of factors which include mass transport, surface properties and surface interactions dictate whether foulants are able to adhere to a surface. Passive means of foulant rejection, such as the microscopic patterns, have been known to develop in nature. In this work, we investigate the anti-fouling behaviour of animal fur and its apparent passive resistance to fouling. We compare the fouling performance of several categories of natural and manufactured fibres, and present correlations between contamination susceptibility and physio-mechanical properties of the fibre and its environment. Lastly, we present a correlation between the fouling intensity of a fibre and the cumulative impact of multiple interacting factors declared in the form of a dimensionless group. Artificial and natural hair strands exhibit comparable anti-fouling behaviour in flow, however, the absence of flow improves the performance of some artificial fibres. Among the plethora of factors affecting the fouling of fur hair, the dimensionless groups we present herein provide the best demarcation between fibres of different origin.