Noise Measurement Setup for Quartz Crystal Microbalance

Quartz crystal microbalance (QCM) is a high sensitive chemical sensor which has found widespread spectrum of applications. There are several mechanisms that are related to fluctuation phenomena. Since the aim of our research is oriented to study the sensitivity and influence of different kind of noises on sensor resolution, we modified an existing method to measure the small frequency fluctuation of QCM. The paper describes our measurement setup, in which a quartz crystal oscillator with coated active layers and a reference quartz oscillator are driven by two oscillator circuits. Each one regulates a frequency of a crystal at the minimum impedance which corresponds to the series resonance. A data-acquisition card triggers on the rise-edges of the output signal and stores these corresponding times on which the instantaneous frequency is estimated by own-written software. In comparison to other measurement setups, our approach can acquire immediate change of QCM frequency, thus, chemical processes can be even described on the basis of high-order statistics. The experiments were provided on quartz crystals with the sorption layer of polypyrrole, which is suitable for the construction of QCM humidity sensors

Noise in piezoelectric ceramics at the low temperatures

The piezoelectric ceramic belongs to materials with widespread spectrum of applications. It can be found in sensors as well as in ceramic capacitors. The main sources of voltage or current fluctuation in piezoelectric ceramics are thermal noise, polarization noise and low frequency 1/f noise. The observed spectra of fluctuating voltage or current can be very well described by the generalized Nyquist relation for linear dissipative system. In this work, we focused on validity of the Nyquist relation for piezoelectric ceramics in temperatures 150 K-270 K. The electrical impedance and noise spectral density are measured and compared in frequency range 100 kHz - 1 MHz. The measurements were made in thermal stable condition and under equilibrium conditions in the case of noise measurement

Activation Energy of RTS Noise

Low frequency noise was measured in silicon MOSFET and GaN and InGaAs based HFET devices with special emphasis on the RTS noise. The RTS (Random Telegraph Signal) dependence on the biasing conditions and temperature was analyzed in order to obtain new information regarding production technology. From the time dependence of the RTS noise voltage the mean time of charge carriers capture and emission by traps in the gate oxide layer was determined as a function of applied gate and drain voltage or electron concentration and then several important trap parameters, such as activation energy and position in the channel could be estimated

Measurement of Mass Transfer Coefficients in Airlift Reactors with Internal Loop Using the Glucose Oxidase Method

This study deals with the measurement of volumetric mass transfer coefficients (kLa) in the internal loop airlift reactors (ILALRs) of different volumes (12 dm3, 40 dm3 and 200 dm3) using the glucose oxidase method. The experimental results of this work were compared with those kLa obtained for the same ILALRs by applying different other methods. Results of this work showed a good agreement with the published results obtained by applying other methods on the non-coalescent medium. The initial glucose mass concentration in the non-coalescent medium was 150 g dm–3. Based on this work, the values of the empirical parameter in the correlation of kLa vs. the total gas hold-up, proposed by Bello et al.,1 were established

From Marxan to management: ocean zoning with stakeholders for Tun Mustapha Park in Sabah, Malaysia

Tun Mustapha Park, in Sabah, Malaysia, was gazetted in May 2016 and is the first multiple-use park in Malaysia where conservation, sustainable resource use and development co-occur within one management framework. We applied a systematic conservation planning tool, Marxan with Zones, and stakeholder consultation to design and revise the draft zoning plan. This process was facilitated by Sabah Parks, a government agency, and WWF-Malaysia, under the guidance of the Tun Mustapha Park steering committee and with support from the University of Queensland. Four conservation and fishing zones, including no-take areas, were developed, each with representation and replication targets for key marine habitats, and a range of socio-economic and community objectives. Here we report on how decision-support tools informed the reserve design process in three planning stages: prioritization, government review, and community consultation. Using marine habitat and species representation as a reporting metric, we describe how the zoning plan changed at each stage of the design process. We found that the changes made to the zoning plan by the government and stakeholders resulted in plans that compromised the achievement of conservation targets because no-take areas were moved away from villages and the coastline, where unique habitats are located. The design process highlights a number of lessons learned for future conservation zoning, which we believe will be useful as many other places embark on similar zoning processes on land and in the sea

Policy drivers of international entrepreneurship in Europe

The diversity of countries and cultures in Europe necessitates an international outlook for most businesses. This paper examines the internationalisation of business in Europe through a literature review on international entrepreneurship theory. The role of the individual business owner and of business and interorganisational activity in facilitating the internationalisation of businesses in Europe is discussed by utilising the theoretical framework of international entrepreneurship and by putting forward three main propositions. The main aim and intent of this paper is to understand how the policies of individual governments and institutions such as the European Union help businesses in Europe to internationalise, with particular emphasis on businesses in the Baltic region. The paper discusses policy implications and suggestions for future research, which highlight the importance for firms in Europe of focussing on international markets.<br /