Timayui幼儿园

精选理由项目由六个像花一样的体量构成,它们有机地散落在基地中,将室外空间融合到幼儿园的平面中区。这些分离的体量由一系列延伸的悬臂连接,每座建筑的内部还设计了天窗,自然光线从带角度的墙面倾泻而下,为学生提供了明亮的室内环境。     

Analysis and Design of a Double-Quadrature CMOS VCO for Subharmonic Mixing at Ka-Band

In this paper, we analyze the potentials of a four-phase 14-GHz CMOS voltage-controlled oscillator, tailored to a sub-harmonic receiver, for signal processing at Ka-band. When mild phase accuracies between in-phase and quadrature down-converted signals are required, the four-phase oscillator displays roughly the same phase noise figure-of-merit as quadrature oscillator counterparts. However, the operation at half-frequency leads to an improved performance due to a higher quality factor of the tuning varactors, and because the local oscillator circuitry and signal path run at different frequencies, relaxing coupling issues. A detailed time-variant analysis of phase noise in multiphase oscillators is introduced and validated by both simulations and experiments. Prototypes realized in a 65-nm technology occupy an active area of 0.5 mm² and show the following performances: a 26% frequency tuning range (from 12.2 to 15.9 GHz), maximum phase error from pi/4 of 2deg, and a phase noise of -110 dBc/Hz at 1 MHz from 14 GHz, while consuming 18 mA from 0.8-V supply.     

Content of flavonols in Italian bean (Phaseolus vulgaris L.) ecotypes

Methanol extracts of seeds from 23 accessions of 3 Phaseolus vulgaris ecotypes (“Sarconi”, “Lamon”, “Zolfino del Pratomagno”), grown in different Italian regions (Basilicata, Veneto, Tuscany) were analyzed for their flavonoid content. Flavonoid glycosides were found in the seed coat from ten accessions of the “Zolfino” ecotype and in one accession of the “Sarconi” ecotype. From highest to lowest concentration these compounds were kaempferol 3-O-glucoside (compound 2), kaempferol 3-O-xylosylglucoside (compound 1) and a not completely identified kaempferol monoglucoside (compound 3). Total flavonol content varied from 0.19 to 0.84 g/kg of seed fresh weight. A great variability in the total flavonol content, being between 18% and 50%, and in the relative abundance of different kaempferol derivatives was observed for the same genotypes sampled in the original locations in the 2001–2003 period. Fluctuation in flavonol content suggests that further researches are necessary for an exhaustive comprehension of physiological mechanisms influencing the expression of these phenolic compounds. Obtained results evidenced that some Italian bean ecotypes may be an important source of functional compounds as kaempferol glycosides.     

Electrical aging and life models: the role of space charge

This paper has the aim of providing a view of a lively debated topic which has broad impact on the design of electrical apparatus and new insulating materials, that is, the interaction between space charge and aging processes of polymeric insulation. Aging models developed in recent decades that consider explicitly or implicitly the contribution of space charge to insulation degradation, under both DC and AC voltage, are dealt with, with the intention to point out their range of validity. Some conventional phenomenological models that have been used for much more than two decades without referring to space charges can be exploited to account for electrical field and activation energy modification due to space charge. These, together with models conceived considering space charges as the driving force for aging, are especially examined. In addition, recent models that disregard the action of space charge as an ageing factor, but consider space charge as the consequence of degradation processes are also discussed.     

Micropatterned substrates: approach to probing intercellular communication pathways

Intercellular signaling is critical for the normal development and physiology of the central nervous system (CNS). To study such signaling, it is vital to control where and when the cells make contact with one another. It is also important to determine whether the process used for cell localization has an impact on signaling. This paper describes a technique that controls the location for cell growth in vitro and demonstrates that the technique has minimal (if any) impact on intercellular signaling. By using photolithographic methods, poly(dimethylsiloxane) molds were fabricated to function as templates for micrometer-level patterning of a nonadhesive agar (agarose) onto glass coverslips coated with a cell adhesive film (poly(L-lysine)). This process yields a surface composed of well-defined adhesive and nonadhesive microdomains. When endothelia or astrocytes are plated onto these substrates, confluent domains of endothelia or astrocytes grow on the poly(L-lysine) domains. Cocultures of astrocytes and neurons can also successfully be used to form interwoven networks on the adhesive domains. Moreover, studies of calcium signaling revealed that astrocytes grown on such patterns retain their native physiological activity. This conclusion is based on the observed propagation rate for calcium waves within individual astrocyte domains and across neighboring, but spatially disconnected, astrocyte domains. The potential to apply these micropatterned substrates as platforms for interrogating communication pathways in key components of the CNS is discussed.     

Physics-based explanation of kink dynamics in AlGaAs/GaAs HFETs

The physical origin of the kink and its dynamics are investigated in AlGaAs/GaAs doped-channel heterostructure field-effect transistors (HFETs) both through measurements and two-dimensional (2D) device simulations. The kink is shown to arise from the interaction of surface deep acceptors with impact-ionization-generated holes, the latter partially discharging the deep levels and therefore leading to conductive-channel widening and to drain-current increase. Under pulsed operation, kink dynamics is governed by hole emission and capture phenomena, prevailing at low and high drain-source voltages, respectively     

Life model based on space-charge quantities for HVDC polymeric cables subjected to voltage-polarity inversions

This paper illustrates a new model that enables the estimation of life of polymeric insulation subjected to DC stress, both in the presence and in the absence of voltage polarity inversions. The derivation of the model parameters is based on the results of space charge measurements and accelerated life tests realized at constant DC stress, which allows the characterization of the performance of insulating materials under DC electrical stress to be carried out in short times. The expected life of a cable in service can be evaluated by means of this model, provided that the rate of voltage inversions expected during its life is known or estimated. The model is applied here to results of tests carried out on polyethylene-based materials for cable insulation, and model parameters are calculated resorting to two different approaches. A satisfactory fitting of life test results is achieved, thus confirming the validity of the proposed model.     

Estimating Thermodynamic Properties of Pure Triglyceride Systems Using the Triglyceride Property Calculator

To date, the most comprehensive model for predicting thermodynamic properties of pure triglycerides was presented by Wesdorp in “Liquid-multiple solid phase equilibria in fats: theory and experiments” (1990). In this paper, we present (1) corrections to the published model, as well as (2) a software implementation of the model for numerical assessment. The software tool, Triglyceride Property Calculator (TPC), uses a semi-empirical model to estimate the enthalpy of fusion and melting temperature for a given triglyceride based on its molecular composition and polymorphic form. These estimates are compared to experimentally collected data when available. The web application is available at http://www.crcfoodandhealth.com (under research tools) and through the AOCS Lipid Library. The quality of estimates is characterized according to defined counting metrics and presented for TAG subcategories. Additionally, the extrapolative value of the TPC is assessed by checking for consistency with underlying thermodynamic constraints. The current TPC implementation is effective in describing experimentally collected melting point data, with greater than 91% of the fitted values falling within 10% of the actual data. The TPC is also very good at describing collected enthalpy data. The underlying semi-empirical model and parameter set perform well in ensuring enthalpy predictions are thermodynamically consistent, however, extrapolated melting temperatures appear unreliable. Developing models and parameter sets that ensure thermodynamic consistency is a priority with future TPC iterations.     

Relation between space charge accumulation and partial discharge activity in enameled wires under PWM-like voltage waveforms

It has been observed that voltage waveforms generated by power electronic converters may affect significantly the reliability of electric motor insulation. Since partial discharges are considered to be the main cause of the reliability loss, new enamel insulations for magnet wires are being developed in order to withstand better stress amplification. The electrical characterization of these insulating materials is often carried out through aging tests which may provide estimation of life under different stress levels and conditions. However, deeper investigation of aging phenomena due to supply voltage waveforms is needed, especially regarding the relation between aging factors and stress conditions. This paper deals with this topic, showing experimental evidences of relation between partial discharge quantities (e.g., inception voltage, repetition frequency, amplitude) and electrical properties, associated with charge accumulation, which can be directly evaluated through space charge measurements. Characterization of insulating materials and comparison of materials candidate for application in power electronic waveform environment can be carried out resorting to the methodology proposed here. This approach can provide, therefore, a useful feedback to wire manufacturers regarding, e.g., the choice of additive nature and enamel components for magnet wires in power-electronic controlled motors.     

Quantities extracted from space-charge measurements as markers for insulation aging

The relation of space charge-derived quantities with aging stresses and time is discussed in this paper. Polyethylene-based materials, aged for different times under electrical and/or thermal stress, are subjected to space charge measurements. Quantities are derived, that is, the threshold for space charge accumulation and the apparent, trap-controlled mobility, obtained by the threshold and the depolarisation characteristics, respectively, which show time variations depending on the level of applied stress and aging time, i.e. on the extent of degradation. This indicates that such quantities can be considered as aging markers useful for the diagnosis of bulk degradation in insulation systems aged under electrical field, dc or ac, and temperature.