Marek Jaskula

Accuracy Analysis of Measurements in Electrochemical Biosensing

In the paper the results of research on accuracy analysis of measurements in electrochemical biosensing are presented. The scope of performed tests includes EIS (Electrochemical Impedance Spectroscopy) and chronoamperometry, widely used for determination of glucose concentration. Measurement results obtained with two microcontroller systems, designed within a research project, and one reference platform (Autolab system, Metrohm, Netherlands) are compared and discussed. As a result, optimal design solutions may be chosen for microcontroller-based biomeasurement system. In glucosensing, promising results were obtained with the EIS technique in experiments performed using the Autolab system.

Electronic Circuits for Graphene-Based Biosensor

In the paper the results of research on electronic measurement and control systems designed for a multifunctional graphene-based biosensor are presented. Design of different types of biosensing electrodes based on graphene technology is discussed. Development of electronic circuits for read-out of the biosensor signals based on two microcontroller platforms (ATXmega128A1U and STM32F407) is described, including hardware and software design solutions. Comparison of measurement results using both prototype systems in electrochemical biosensing techniques (EIS - Electrochemical Impedance Spectroscopy) is also presented.

Development of the Mobile PoC Graphene-Based Biosensing Device Using Electrochemical Impedance Spectroscopy (EIS)

In the paper the results of research on a multifunctional graphene-based biosensor are presented.

Segmental cues to intonation of statements and polar questions in whispered, semi-whispered and normal speech modes

Abstract This paper examines how acoustic characteristics of vowels and consonants reflect intonational differences between polar questions and statements in Polish whispered, semi-whispered and normal speech modes, with particular focus on the spectral characteristics of voiceless consonants as a function of intonation, and across speech modes. The results reveal significant differences in spectral properties of both utterance-final vowels and consonants across statements and polar questions. Questions have higher vowel intensities and show differences in formant frequencies that vary with speech mode. Regarding the consonants, both fricatives and affricates are produced with higher intensity, spectral peaks at higher frequencies, and higher Centre of Gravity and Spectral Standard Deviation values in questions than in statements. Conversely, skewness and kurtosis are lower in questions than in statements. Some spectral features of sibilants, including spectral slopes, show greater question-statement differences in the whispered speech mode than in other speech modes. The finding that some cues are more pronounced in whispered speech suggests that they may compensate for the absence of fundamental frequency in this mode. Most generally, the study shows that speakers produce intended intonation patterns by varying the type and magnitude of cues depending on speech mode.

The Phonetics and Phonology of the Polish Calling Melodies

Two calling melodies of Polish were investigated, the routine call, used to call someone for an everyday reason, and the urgent call, which conveys disapproval of the addressees actions. A Discourse Completion Task was used to elicit the two melodies from Polish speakers using twelve names from one to four syllables long; there were three names per syllable count, and speakers produced three tokens of each name with each melody. The results, based on eleven speakers, show that the routine calling melody consists of a low F0 stretch followed by a rise-fall-rise; the urgent calling melody, on the other hand, is a simple rise-fall. Systematic differences were found in the scaling and alignment of tonal targets: the routine call showed late alignment of the accentual pitch peak, and in most instances lower scaling of targets. The accented vowel was also affected, being overall louder in the urgent call. Based on the data and comparisons with other Polish melodies, we analyze the routine call as LH* !H-H% and the urgent call as H* L-L%. We discuss the results and our analysis in light of recent findings on calling melodies in other languages, and explore their repercussions for intonational phonology and the modeling of intonation.

Do children understand adults better or themselves? A perceptual study of Polish /s, ʂ, ɕ/

Developmental studies of speech perception have typically used adult productions or synthetic speech as stimuli. Little is known about how children perceive their own speech, however. Further, few studies of sibilant fricative perception have explored complex sibilant inventories. This work assessed perception of the sibilants /s, ʂ, ɕ/ in 32 monolingual native speakers of Polish, 3–8 years of age. Children participated in a picture-naming task to identify minimal or near-minimal triplets with the fricatives in initial and medial position, e.g., [kasa] “cash point”, [kaʂa] “groats”, [kaɕa] “Cathe, prop.name.” They subsequently labeled their own word productions, and the words as produced by an adult. Children’s labeling was generally quite accurate for the adult speaker, with the lowest accuracy rating of ca. 75% seen in the youngest listeners. When labeling themselves, the children were less accurate, with average performance at about 50% in children younger than 55 months. Across all ages, reaction times decreased in the order /ʂ/ > /s/ > ɕ/. Future work will obtain perceptual judgments of the children’s productions from other listeners and obtain acoustic measures of the fricatives to explore perception-production relationships.Developmental studies of speech perception have typically used adult productions or synthetic speech as stimuli. Little is known about how children perceive their own speech, however. Further, few studies of sibilant fricative perception have explored complex sibilant inventories. This work assessed perception of the sibilants /s, ʂ, ɕ/ in 32 monolingual native speakers of Polish, 3–8 years of age. Children participated in a picture-naming task to identify minimal or near-minimal triplets with the fricatives in initial and medial position, e.g., [kasa] “cash point”, [kaʂa] “groats”, [kaɕa] “Cathe, prop.name.” They subsequently labeled their own word productions, and the words as produced by an adult. Children’s labeling was generally quite accurate for the adult speaker, with the lowest accuracy rating of ca. 75% seen in the youngest listeners. When labeling themselves, the children were less accurate, with average performance at about 50% in children younger than 55 months. Across all ages, reaction time...

Application of higher relative degree sliding variables for congestion control in communication networks

In this paper we introduce a new design method of the sliding mode controller for connection oriented communication networks. To determine the controller we transform the state matrix describing the network dynamics into the Frobenius form and select the sliding variable with relative degree less than or equal to the order of the system. Data losses and transmission delays are taken into consideration. The design method proposed in this paper results in finite time queue length convergence to its demand value. This desirable property is obtained without the need of explicit selection of the closed-loop system state matrix eigenvalues. Then, a time-varying sliding hyperplane is introduced in order to constrain the data flow rate at the beginning of the control process.

Sliding Mode Control of Discrete Time Dynamical Systems with State Constraints

In this paper, we study the problem of state and control signal constraints in discrete-time sliding mode control. We introduce a sufficient condition for finite time convergence of the representative point to the sliding hyperplane, while respecting imposed restrictions. We propose a new control strategy based on the reaching law approach.

The effect of lowering the resonant frequency of the loudspeaker during impedance measurement as a function of the signal power

One of the main loudspeaker (woofer) characteristics is its voice coil impedance as a function of frequency. Its measurement is made using sinusoidal test signal (with very low harmonic content), which is feed from generator trough the power amplifier to the loudspeaker. The voltage across the voice coil is acquired directly and the current is measured as a voltage across the resistor with known value connected in series with the voice coil. As a standard a loudspeaker is driven with constant current so the supplied power varies with frequency, but should not overcome the value of 1 Watt. The authors propose to augment this procedure and to measure impedance characteristics at different power levels. In such a way the changes in resonance frequency of the loudspeaker can be observed, which as the experiments have shown, are quite noticeable and are correlated with nonlinear distortion level introduced by the loudspeaker. So the shift of the resonance frequency can be used as an assessment cue in a automatic quality testing of the transducer.