Search results

Amperometric gas sensors are commonly used in air quality monitoring in long-term measurements. Baseline shift of sensor responses and power failure may occur over time, which is an obstacle for reliable operation of the entire system. The purpose of this study is to check the possibility of using PCA method to detect defected samples, identify faulty sensor and correct the responses of the sensor identified as faulty.

In this work, the authors present the results obtained with six amperometric sensors. An array of sensors was exposed to sulfur dioxide at the following concentrations: 0 ppm (synthetic air), 50 ppb, 100 ppb, 250 ppb, 500 ppb and 1000 ppb. The damage simulation consisted in adding to the sensor response a value of 0.05 and 0.1 µA and replacing the responses of one of sensors with a constant value of 0 and 0.15 µA. Sensor validity index was used to identify a damaged sensor in the matrix, and its responses were corrected via iteration method.

The results show that the methods used in this work can be potentially applied to detect faulty sensor responses. In the case of simulation of damage by baseline shift, it was possible to achieve 100% accuracy in damage detection and identification of the damaged sensor. The method was not very successful in simulating faults by replacing the sensor response with a value of 0 µA, due to the fact that the sensors mostly gave responses close to 0 µA, as long as they did not detect SO₂ concentrations below 250 ppb and the failure was treated as a correct response.

This work was inspired by methods of simulating the most common failures that occurs in amperometric gas sensors. For this purpose, simulations of the baseline shift and faults related to a power failure or a decrease in sensitivity were performed.

The purpose of this work is to present the strategies and current state of development in the field of micro solid oxide fuel cells (μSOFC).

In the paper recent strategies of conventional and single chamber μSOFC are described. Some examples based on the author's research are presented.

It can be concluded that scale down of ceramic technologies is still more popular than MEMS. However, MEMS‐based technologies become recently to be used more frequently.

The work is limited to the description of materials and technologies used in μSOFC.

The review presents very recent research in μSOFC. The results demonstrate critical areas in development of suitable technologies.

Innovation policy and innovation systems undoubtedly play a crucial role in shaping the path of economic development of contemporary economies. A particularly interesting context for studying the evolution of this area is offered by post-transition economies which had to undergo fundamental structural changes and face the global competition where the advances in knowledge and technological progress ultimately decide between success or failure.

The chapter aims to portray and evaluate the key developments in the innovation policy and national innovation system of Poland – one of the largest and most successful post-transition economies.

The methodological framework of the study involves a descriptive analysis of the major changes in the regulatory and institutional settings as well as an analysis of statistical data on the crucial dimensions of Poland's innovation policy and innovation system over the period 2000–2021. Additionally, the overall effects of the policy have been assessed using the data from the European Innovation Scoreboard (over 2015–2022) and the Global Innovation Index (over 2008–2022).

The findings suggest that the significant changes in Poland's innovation policy and innovation system frameworks introduced since the mid-2000s have resulted in a dynamic increase in the intensity of R&D efforts, especially in the business enterprise sector, allowing to narrow the structural gaps dividing the country from more advanced economies and markedly improve its overall research and innovative performance. A key role in this process has been played by the direct and indirect government support for innovative activities.

The purpose of this study is to synthesize the literature on the topic of strategic renewal by identifying the key dimensions of extant research and the connections between fragmented research domains.

This study applies systematic literature review to identify the level of consistency and generalizability of research findings across existing studies in a comprehensive manner.

This study identifies six main themes of strategic renewal in the extant literature: (1) antecedents, (2) initiation, (3) logic, (4) structure, (5) process and (6) outcomes of strategic renewal.

By integrating the current streams of research, the review offers a conceptual model of strategic renewal that maps the current state of the research and provide insights into key themes for the future research.

This study, identifies connections between fragmented research domain and offers a conceptual framework of strategic renewal.

The paper aims to emphasise how switched systems can be analysed with elementary techniques which require only undergraduate-level linear algebra and differential equations. It is also emphasised how math software can become useful for simplifying analytic complications.

The time domain voltage balance methodology is used for stability analysis. As for deriving formulas for the asymptotic average of both capacitor voltage and inductor current, a new simple analytic method is introduced.

It was shown analytically that the time average of capacitor voltage converges to half of the source voltage. A formula for the time average of the current of the inductor is also computed. As a by-product, it was discovered that the period of the current is half of the switching period. Numerical simulations are obtained to illustrate the accuracy of the results.

Higher dimensional generalisations could become a bit complicated, as stability analysis of higher dimensional exponential matrices is not so easy to handle. On the other hand, the new discovery on the period of the current is more likely to give new insights into handling higher dimensional systems.

Analytical formulas are exact, and it helps in accurately modelling flying capacitor converts (FCCs) in practice.

FCC is well studied in engineering society. However, not much is done in obtaining closed form solutions using analysis. Also, math software is much used in computation of numerical results and obtaining simulations. In this paper, one more important aspect of math software is emphasised, namely, use symbolic and numeric computing environment Maple in analysis.

The purpose of this paper is to present possibility of fast and certain identification of bovine serum albumin (BSA) by means of ion-sensitive field effect transistor (ISFET) structures. Because BSA can cause allergic reactions in humans, it is one of reasons for development of sensitive sensors to detect residual BSA. BSA is commonly used in biochemistry and molecular biology in laboratory experiments. Therefore, to better understand the mechanism of signal transduction in simulated biological environment and to elucidate the role of adsorption of biomolecules in the generation of a signal at the interface with biological systems, the measurements of ISFET current response in the presence of BSA as a reference protein molecule were performed.

To fabricate transistors, silicon technology was used. The ISFET structures were coupled to specially designed double-side printed circuit board holder. After modification of the field effect transistor (FET) device with 3-aminopropyltriethoxysilane (APTES), a sensor with high sensitivity toward reference biomolecules was obtained. The current–voltage (I-V) characteristics of structures with and without gate modification were measured. Keithley SMU 236/237/238 measurement set was used. Deionized water solution and 0.05 per cent BSA were used.

In this research, a method of preparation of a biosensor based on a FET was developed. Sensitivity of APTES-modified FET device toward BSA as a biomolecule was investigated. I-V relationships of FET devices (with and without modification), being the effect of the interactions with the solution containing 0.05 per cent BSA, were measured and compared to the measurements performed for solutions without BSA.

Compared to SiO₂-containing ISFETs without modification or other different dielectrics, the application of APTES as the part of the membrane induced significant increase in their sensitivity to BSA.

Although there are many journalistic accounts of ongoing political events narrating about pro-democratic or antiauthoritarian movements, such as strikes, riots, and protest letters, not many scholarly analyses devote attention to the longitudinal analysis of the preceding events that lead to a spur of protests. Not many scholars account or are able to account for the activity of political dissidents that is often hidden, purposely censored, and covered from public eye. Most frequently, until the street strike and riots, the degree of spread of dissident activity within a country is unknown to scholars. It is equally difficult to find information about the national and international networks that political activists form to gain support and acceptance of their acclamations, propositions, and calls for political or economic reforms. Furthermore, only access to dissident press allows researchers to glimpse the activity of existing organizations looking at issues censored by existing governments.

In January of 1999, following the philosophy of community oriented policing, the Polish National Police restructured its organization. This article presents results of two phases out of a larger research project conducted with the Polish police and community members representing diverse environments including college students, politicians, and media representatives. Our results represent an analysis of over 2,000 questionnaires distributed to the members of the Polish police and contrasted against data collected from hundreds of questionnaires answered by college students in three cities. The questionnaire was designed to measure the degree of understanding of the role of the police in a democratic society, as perceived by both the public and the police. Some of the main principles of community‐oriented – problem‐solving policing are revisited in the questionnaire, providing a baseline for discussion about the feasibility of implementation of a philosophical paradigm in real‐life environments, when the actors involved have no clear concept about the roles they are supposed to play.