Artículos de revistas sobre el tema "Asynchronous Transducers"

The article presents a three-phase current transducer for filter-compensation devices, representing the value of the stator current of an asynchronous motor. An algorithm for determining the values of the output electric quantities in them was developed based on the methods of interconnecting the loops of the sensitive element of the three-phase electromagnetic current transducer arranged in accordance with the stator slots of the asynchronous motor. In addition, based on this algorithm, the time-dependent dynamic characteristics of the output signal of the sensitive element loops are determined according to the connection method. Based on the dynamic description, it is possible to see the time for the output voltage signal of the three-phase current transducer to reach stability and the effect of high harmonic currents affecting it. Theoretical studies were carried out in Matlab program, and practical studies were carried out using CassyLab device. The theoretical and practical results determined because of research are compared with each other.

This article uses a controlled output voltage-to-current converter to control the reactive power of an induction motor. The dynamic characteristics of the current converter were obtained using the Simulink program, taking into account reliability, sensitivity, measurement accuracy and error. Current converters are mainly operated during normal stable operation of the power supply system of an asynchronous motor. In this mode, when studying current transducers with certain conditional limits, the minimum and maximum values of the input current are accepted, for which the accuracy class (0.1‒1.2)∙Inom is set. Damage to electrical equipment and networks can lead to emergency operation of the power supply system of an asynchronous motor, in which case the current converters operate in dynamic mode. Short circuits in an asynchronous motor are the main reason for the operation of electromagnetic current converters in dynamic modes. The operating conditions of electromagnetic current adapters in such modes differ significantly from the operating conditions in the control system circuits. If electromagnetic current adapters are used for measurement purposes, they are usually required to operate at a primary current not exceeding the rated current and must perform their functions in the event of a fault.

Hemodynamic and ventricular energetic parameters were measured in calves implanted with the air driven Utah Ventricular Assist Device (UVAD). Uptake site was varied to determine the effect of control mode and vacuum augmentation of filling. Uptake was drawn solely from the left atrium or combined with a left ventricular apical vent. LVAD outflow returned to the descending, thoracic aorta. Control modes examined included asynchronous pumping as well as 1:1 and 1:2 synchronous diastolic counterpulsation. The 85cc LVAD, vacuum formed from PELLETHANE®, was implanted acutely in four animals and chronically in six (7, 49 and 116 days paracorporeally, 1, 28 and 32 days intrathoracically). Instantaneous blood pressures, intramyocardial pressure, aortic outflow, oxygen consumption, LVAD output and drive parameters were recorded. LVAD output was independent of control mode when the natural heart rate was ≥ 80 beats per minute. Intrathoracically positioned LVADs pumped a mean flow of ≈5 liters/min without vacuum augmentation of filling. Paracorporeally positioned LVADs pumped ≈3 liters/min mean flow without vacuum augmentation and up to ≈6 liters/min with 38 mm Hg of vacuum augmentation of filling. Instantaneous ascending aortic pressure and flow showed distinct beat-to-beat variation depending on LVAD control mode. Lower average ventricular afterload was observed when pumping the LVAD asynchronously or 1:2 synchronously. In one acute preparation, left ventricular myocardial oxygen consumption was reduced from the unassisted average control level by 37% for the asynchronous and 1:1 synchronous control modes with left atrial uptake. With combined uptake, oxygen consumption was reduced an additional 30% during asynchronous control or 11% during 1:1 synchronous control without any change in LVAD output. Endocardial/epicardial blood flow ratio was similar and ≥1.12 for all test conditions. Renal and brain blood flow was maintained, or slightly elevated during ventricular assistance. Intramyocardial pressures were monitored using Millar catheter tip transducers. In an acute preparation, left ventricular assistance reduced peak intramyocardial pressure. Changing from atrial to combined uptake cannulation further reduced peak intramyocardial pressure for asynchronous and 1:1 synchronous LVAD control. Reduced end-diastolic intramyocardial pressures were seen with all modes of LVAD control. These data demonstrate excellent UVAD pumping function and suggest that left ventricular assistance does not compromise endocardial blood flow while sustaining blood flow to other major organs. Regardless of the uptake site, asynchronous or 1:2 synchronous LVAD control may be clinically preferable for effective reduction of left ventricular myocardial oxygen consumption.

bstract: The increasing demand of load without considerable increase in transmission resources has posed numerous constraints and challenges in the power system monitoring and performance. Modern power system grid monitoring tools use data from remote terminal units (RTUs), protective relays, and transducers to provide information to system operators. This information is vital for the operation of the power system on a daily basis and under system contingencies. However, the method presently available to retrieve data from the devices is asynchronous and relatively slow. The asynchronous nature of the data does not provide accurate angle difference information from two nodes on the network. Moreover, the low data rate may be too slow to capture many short-duration disturbances on the grid. Alternatively, Synchrophasors based technology can be used to provide high-speed and coherent real-time information of the power system that is not available from legacy supervisory control and data acquisition (SCADA) systems.

One of the possible fields of application of the impedance method based on the use of impedance and its components as an informative parameter is considered. This area of work is the study and diagnosis of asynchronous motors in dynamic mode. The paper presents both a T – shaped scheme of replacement of an asynchronous motor and one of its possible mathematical models, on the basis of which conclusions were made about the feasibility of applying the impedance method for the study and diagnosis of asynchronous motors and the need to develop hardware for this method. In this regard, the main part of the work is devoted to the consideration of measuring transducers necessary for both the technical implementation of the method as a whole, and the instrument support of the method. The option to build transmitters that use the basis four-armmeasuring bridge circuit known as a Wheatstone bridge. The first сonverter is easier to implement because it is implemented on the basis of the Whitstonbridge with one feedback, but is characterized by less functionality. The second converter is implemented more difficult, as it is also implemented on the basis of the Whitstonbridge, but with two feedbacks. However, this version of the converter has more functionality.

The subject of the research contained in this paper is a new design solution for an energy harvesting system resulting from the combination of a quasi-zero-stiffness energy harvester and a two-stage flexible cantilever beam. Numerical tests were divided into two main parts-analysis of the dynamics of the system due to periodic, quasiperiodic, and chaotic solutions and the efficiency of energy generation. The results of numerical simulations were limited to zero initial conditions as they are the natural position of the static equilibrium. The article compares the energy efficiency for the selected range of the dimensionless excitation frequency. For this purpose, three cases of piezoelectric mounting were analyzed-only on the first stage of the beam, on the second and both stages. The analysis has been carried out with the use of diagrams showing difference of the effective values of the voltage induced on the piezoelectric electrodes. The results indicate that for effective energy harvesting, it is advisable to attach piezoelectric energy transducers to each step of the beam despite possible asynchronous vibrations.

In asynchronous electric drives with vector control on the rotor, it is necessary to calculate the value of the sine and cosine of the angle of rotation of the rotor relative to the stator to form control actions. When using angle sensors, complex structural tasks can arise — placement and reliable mounting of the sensor on the shaft and, accordingly, the task of the overall layout of the unit. For high-power machines, the tasks of developing and creating the design of the sensor itself arise. If serial rotor angular position sensors can be used, the task of placing and mounting the sensor is no less difficult. In these cases it is necessary to deduce the second end of a shaft from the case of the engine with contact rings that complicates its design. Therefore, the urgent need to create more reliable electric drives with vector control systems on the rotor is the synthesis of identifiers of the angle of rotation of the rotor. Identifiers are known whose calculation algorithms are based on determining the projections of the flow coupling vectors. In the work with the use of coordinate transducers of projections of stator or rotor current vectors and equations of electromagnetic circuits of an asynchronous machine, the synthesis and subsequent analysis of the properties of the rotor position angle identifier in vector control systems of dual power machines is performed. New equations of the identifier of flux couplings are received, its stability is investigated and on conditions of stability types of electric drives in which it is possible to apply the offered identifier are defined. The stability of the vector control system and sufficient identification accuracy when using the proposed equations and functions are confirmed by the method of mathematical modeling of the recommended electric drive systems in different operating modes.

Recruitment of force via independent asynchronous firing of large numbers of motor units produces the grace and endurance of physiological motion. We have investigated the possibility of reproducing this physiological recruitment strategy by determining the selectivity of access to large numbers of independent motor units through intrafascicular multielectrode stimulation (IFMS) of the peripheral nerve. A Utah Slanted Electrode Array containing 100, 0.5–1.5 mm-long penetrating electrodes was inserted into the sciatic nerve of a cat, and forces generated by the 3 heads of triceps surea in response to electrical stimulation of the nerve were monitored via force transducers attached to their tendons. We found a mean of 17.4 ± 4.9 (mean ± SEM) electrodes selectively excited maximal forces in medial gastrocnemius before exciting another muscle. Among electrodes demonstrating selectivity at threshold, a mean of 7.3 ± 2.7 electrodes were shown to recruit independent populations of motor units innervating medial gastrocnemius (overlap < 20%). Corresponding numbers of electrodes were reported for lateral gastrocnemius and soleus, as well. We used these stimulation data to emulate physiological recruitment strategies, and found that independent motor unit pool recruitment approximates physiological activation more closely than does intensity-based recruitment or frequency-based recruitment.Key words: functional neuromuscular stimulation (FNS), microelectrode array, neuroprosthesis, intrafascicular multielectrode stimulation (IFMS).

A large number of natural and man-made emergencies occurring on the territory of Ukraine, and not only that cause deforestation of buildings, structures, objects and cities and whole districts, require the provision of fire protection systems for sources of electricity that are independent of Electricity supply of certain areas or cities and objects. Regardless of the control mode, elements of automatic fire protection systems are elements that take part in a single technological process (notifying people of danger, feeding, water, removing smoke, etc.). All systems of fire protection (SPPZ), as the main power source use a common grid (220 / 380V AC). In this unchanged form, the electric power is fed to supply power executive elements (asynchronous actuators of water pumps, fans, etc.). To control the operation of fire protection systems, 12-24V DC is used. This requires the use of additional transducers in fire control systems to form the voltage of the corresponding form. Simultaneous exhaustion of tens and hundreds of settlements, as evidenced by the reports of the DNS of Ukraine and other operational services, affects the provision of fire protection of objects and the safety of people [5]. Taking into account the unpredictability of the occurrence of events, it is necessary to apply methods of providing backup power supply independent of power supply and climatic conditions of operation of fire protection systems. The purpose of the work is to propose the optimal way of forming the supply voltage and adjusting its parameters for the backup power of electric consumers of automatic fire protection systems powered by an autonomous power supply, which consists of a unit of battery and autonomous voltage inverters. Such a backup power scheme allows simultaneous control and regulation of the voltage, frequency, and the ability to determine the parameters of the autonomous source elements. In the process of reviewing and assessing the reliability of power supply of electric consumers of automatic fire protection systems, previously noted ways to increase the reliability of the operation of automatic fire protection systems by reserving power supply from autonomous sources with the use of accumulator batteries and autocompressor voltage inverters were taken into account. For comparison, from all known electricians of fire protection systems, the most common and most powerful electric consumer is used - an asynchronous motor. The probabilistic method for calculating the functioning of the backup power supply system for an internal fire-fighting water supply system using generator sets and accumulator batteries with autonomous inverters of voltage, taking into account the accidental nature of the disconnection of power lines, proved that the proposed reservation scheme, both with K2AIN-AD and with 2K2AIN-AD increases the reliability of functioning systems for fire protection. An increase in the number of similar items led to an improvement in the quality characteristics of the power supply, but had a negative impact on reliability, albeit slightly compared to the backup from the two-transformer substation.

<span lang="EN-US">A practical monitoring system implementing an asynchronous interrupt driven sampling technique has been developed in this research. This system is intended to acquire power-line single-phase voltage and current signals as well as their related information such as RMS values and harmonic contents. The system uses a voltage transformer and a current transducer to acquire the signals of the voltage and current. A microcontroller is used in the system to perform acquisition processes, calculation, and wireless data transmission. The design activities include the development of hardware of the system and software in the microcontroller as well as monitoring software with Bluetooth technology that will run on portable devices. As part of the research, a new sampling technique was developed to provide constant and precise timings during the acquisition processes. In this technique, some peripherals related to the acquisition process were driven asynchronously using interrupt mechanisms. Some experimentation has been carried out, and the result showed that the system implementing this technique could successfully manage the timings for the synchronous acquisition sequences. Furthermore, the use of the Bluetooth interfaces in the system allowed practical monitoring process to be performed using portable devices.</span>

In this paper, a new two-step joint optimization approach based on the asynchronous subregion optimization method is proposed for training a pipeline model composed of two different models. The first-step processing of the proposed joint optimization approach trains the front-end model only, and the second-step processing trains all the parameters of the combined model together. In the asynchronous subregion optimization method, the first-step processing only supports the goal of the front-end model. However, the first-step processing of the proposed approach works with a new loss function to make the front-end model support the goal of the back-end model. The proposed optimization approach was applied, here, to a pipeline composed of a deep complex convolutional recurrent network (DCCRN)-based speech enhancement model and a conformer-transducer-based ASR model as a front-end and a back-end, respectively. Then, the performance of the proposed two-step joint optimization approach was evaluated on the LibriSpeech automatic speech recognition (ASR) corpus in noisy environments by measuring the character error rate (CER) and word error rate (WER). In addition, an ablation study was carried out to examine the effectiveness of the proposed optimization approach on each of the processing blocks in the conformer-transducer ASR model. Consequently, it was shown from the ablation study that the conformer-transducer-based ASR model with the joint network trained only by the proposed optimization approach achieved the lowest average CER and WER. Moreover, the proposed optimization approach reduced the average CER and WER on the Test-Noisy dataset under matched noise conditions by 0.30% and 0.48%, respectively, compared to the approach of separate optimization of speech enhancement and ASR. Compared to the conventional two-step joint optimization approach, the proposed optimization approach provided average CER and WER reductions of 0.22% and 0.31%, respectively. Moreover, it was revealed that the proposed optimization approach achieved a lower average CER and WER, by 0.32% and 0.43%, respectively, than the conventional optimization approach under mismatched noise conditions.

<p class="Abstract">A 4^th-order Kalman filter (KF) algorithm is developed based on the thermal model of an asynchronous machine. The thermal parameters are identified and KF is implemented in a wireless sensor network (WSN) to estimate the temperatures of the stator windings, the rotor cage, and the stator core of an asynchronous machine. The rotor speed, coolant air temperature, and the effective current and voltage are acquired by a WTIM (wireless transducer interface module) separately and transmitted to a NCAP (network capable application processor) where the KF algorithm is implemented. Losses of the stator windings and the rotor cage are copper losses, and the stator core losses are iron losses. The losses of the stator windings, the rotor cage and the stator core are calculated from the measurements and are processed with the coolant air temperature by KF. As the resistance varies from temperature, the estimated temperature of the stator windings is used for compensating the rising of resistance. Simulations and experiments on the test bench were performed before the KF algorithm is implemented on a wireless sensor node. The real-time temperature estimator on WSN is independent of control algorithm and can work under any load condition with very high accuracy.</p>

In this article, we will study a system consisting of a wind turbine operating at a variable wind speed and a two-feed asynchronous machine (DFIG) connected to the grid by the stator and fed by a transducer at the rotor side. The conductors are separately controlled for active and reactive power flow between the stator (DFIG) and the network, which is achieved using conventional PI and fuzzy logic. The proposed controllers generate reference voltages for the rotor to ensure that the active and reactive powers reach the required reference values, in order to ensure effective tracking of the optimum operating point and to obtain the maximum electrical power output. System modeling and simulation were examined with Matlab. Dynamic analysis of the system is performed under variable wind speed. This analysis is based on active and reactive energy control. The results obtained show the advantages of the proposed intelligent control unit.

The article highlights the relevance of energy saving problems on a global scale and the need to regulate by state laws the production and application of frequency converters, which allow to reduce the energy consumption of asynchronous motors by 30-60% depending on the load as a result of the International Energy Agency's targeted energy policy. Different characteristics of controlling the asynchronous motor, which is the main transmission of artesian well pumps, with Straight and Frequency Transducer (Variable Frequency Transmission) from the power grid are compared; the principles of energy-saving frequency converter (FC) with pulse-width modulation, increasing the power factor (PF-Power Factor) are interpreted, as well as the principle of operation and bloc explained, including the principle of operation and the block diagram. The authors report on the positive results of the work carried out in the oil fields by the Institute of Control Systems of ANAS together with Cybernetics SDB on the identification of energy-saving sources and finding ways to save energy. The article substantiates the urgency of creating a frequency converter-based monitoring, diagnostic and control system for subartesian well pumps. At the same time, the surface and underground equipment of subartesian wells is studied, technical requirements for an automated control system for early diagnosis and optimal control of their technical condition are formulated, and the structure of a new SCADA system is proposed. A comparative analysis of the operation of the artesian well engine directly and by the FC-based Artesian Well Smooth Control Station (AWSCS) proposed in the system is given for different cases.

Background: Doubly-Fed Induction Generator (DFIG) is a dual input conventional asynchronous device connected across both stator and rotor, which also functions as an electrical transducer consuming up-to 30 % of the generated power during the rotor injection. This is the major concern with respect to the DFIG in terms of effective power generation. Methods: The proposed work provides the solution for this undesirable power loss by connecting the DFIG with an array of solar Photovoltaic (PV) panel through a conventional direct current bus using a boost converter. This research setup can work on the basis of indirect vector control algorithms applied at the rotor and grid converter level in order to maintain the constant DC voltage under arbitrary conditions. Results: Even the variations in voltage and frequency will be controlled with this novel approach. A simulation model of the 300KW solar PV array and a 2MW DFIG system is developed using MATLAB/Simulink environment. Conclusion: Solar and wind energy sources incorporate Maximum Power Point Tracking (MPPT) through their control algorithms resulting in the add on 30-80 KW of solar power for rotor injection compared to the existing system in order to reduce the power rating of the converters and power consumption from the grid.

This paper performs a comparison between Fuzzy-PI regulators and Genetic Algorithm (GA) for controlling an active and reactive Doubly-Fed Induction Generator (DFIG) for providing power to the electrical grid. Theoretical analysis, modeling, and simulation studies are provided. Control strategies were developed for both active and reactive forces in order to optimize energy production. The performance of the two control strategies was examined and compared using benchmarks for durability and reference traceability. This paper studied a system consisting of a wind turbine operating at variable wind speed and a two-feed asynchronous machine (DFIG) connected to the grid by the stator and fed by a transducer at the side of the rotor. The conductors were separately controlled for active and reactive power flow between the stator (DFIG) and the grid, which was achieved in this article using conventional PI and fuzzy logic controllers. The considered controllers generated reference voltages for the rotor to ensure that the active and reactive power reached the required reference values. This was done in order to ensure effective tracking of the optimum operating point and the maximum output of electrical power. System modeling and simulation were examined in Matlab/Simulink. Dynamic analysis of the system was performed under variable wind speed.

Ultrasonic wave is widely used in Structure Health Monitoring (SHM) systems. A piezoelectric transducer (PZT) is one of the most widely used sensors to acquire the structure's ultrasonic wave. As today's world is digital, it is necessary to digitize the traditional analog PZT sensing system. This paper describes the development and analysis of a digital ultrasonic sensing device (DUSD) for PZT sensors. We removed the complexities of the analog circuit by interfacing the microcontroller directly with the charge amplifier circuit. The microcontroller used in this research is a 32-bit ARM Cortex-M4 with in-built FPU (Floating Point Unit) and DSP (Digital signal processing) instructions. These features make it possible to compute complex signal processing algorithms and methods in the controller itself. The developed sensing device can communicate with the user and other devices using Universal Asynchronous Receiver/Transmitter (UART). The user can select cut-off frequencies of both high pass filters (HPF) and low pass filters (LPF) as well as types of data (ultrasonic waves, damage index) that the user wishes to collect from the device. To illustrate the proficiencies of the device, the ultrasonic wave was collected and evaluated to detect the damage in the test specimen.

This paper is interested in studying a system consisting of a wind turbine operating at variable wind speeds, and a two-feed asynchronous machine (DFIG) connected to the grid by a stator and fed by a transducer at the side of the rotor. The conductors are separately controlled for active and reactive power flow between the stator (DFIG) and the grid. The proposed controllers generate reference voltages for the rotor to ensure that the active and reactive power reaches the required reference values, to ensure effective tracking of the optimum operating point and to obtain the maximum electrical power output. Dynamic analysis of the system is performed under variable wind speeds. This analysis is based on active and reactive energy control. The new work in this paper is to introduce theories of genetic algorithms into the control strategy used in the switching chain of wind turbines in order to improve performance and efficiency. Simulation results applied to genetic algorithms give greater efficiency, impressive results, and stability to wind turbine systems are compared to classic PI regulators. Then, artificial intelligent controls, such as genetic algorithms control, are applied. Results obtained in the Matlab/Simulink environment show the efficiency of this proposed unit.

Transient gamma-band (40–80 Hz) spatiotemporal patterns are hypothesized to play important roles in cortical function. Here we report the direct observation of gamma oscillations as spatiotemporal waves induced by targeted optogenetic stimulation, recorded by intracortical multichannel extracellular techniques in macaque monkeys during their awake resting states. Microelectrode arrays integrating an optical fiber at their center were chronically implanted in primary motor (M1) and ventral premotor (PMv) cortices of two subjects. Targeted brain tissue was transduced with the red-shifted opsin C1V1(T/T). Constant (1-s square pulses) and ramp stimulation induced narrowband gamma oscillations during awake resting states. Recordings across 95 microelectrodes (4 × 4-mm array) enabled us to track the transient gamma spatiotemporal patterns manifested, e.g., as concentric expanding and spiral waves. Gamma oscillations were induced well beyond the light stimulation volume, via network interactions at distal electrode sites, depending on optical power. Despite stimulation-related modulation in spiking rates, neuronal spiking remained highly asynchronous during induced gamma oscillations. In one subject we examined stimulation effects during preparation and execution of a motor task and observed that movement execution largely attenuated optically induced gamma oscillations. Our findings demonstrate that, beyond previously reported induced gamma activity under periodic drive, a prolonged constant stimulus above a certain threshold may carry primate motor cortex network dynamics into gamma oscillations, likely via a Hopf bifurcation. More broadly, the experimental capability in combining microelectrode array recordings and optogenetic stimulation provides an important approach for probing spatiotemporal dynamics in primate cortical networks during various physiological and behavioral conditions.

Abstract The International Space Station (ISS) offers a unique macroenvironment to study biology. The effects of microgravity in low earth orbit (LEO) can be leveraged to study pre-cancer and cancer transformation in an accelerated timeframe. Thus, we launched two cancer cell types into space as a proof of concept and to establish an innovative model for studying cancer. The two cell types are TF1a, an erythroleukemia cell line, and Caco-2, a colon cancer cell line that was cultured as organoids. These studies were performed in collaboration with Axiom Space and were launched as part of the Ax-1 mission on April 8, 2022. To study these tumor organoids in space, cells were transduced with two lentiviral reporters, ADAR1 NanoLuciferase reporter, an A-to-I editing reporter, and Fucci2BL, a cell-cycle transit reporter. Fluorescent imaging at days 5 and 6 of the mission, courtesy of KEyence Research MIcroscope Testbed (KERMIT), allowed us to receive and assess the development of these tumor models in real-time. Caco-2 organoids in flight grew 3-5 times bigger than their ground counterparts. Preliminary whole genome sequencing (WGS) analysis showed that telomere length is shortened in flight samples compared to asynchronous ground control samples. In summary, research done in LEO has the capacity to strengthen terrestrial research. As we follow-up with these studies as part of the Ax-2 mission in May of 2023, we hope to gain more insight into the pathogenesis of cancer and develop strategies to mitigate cancer progression. Citation Format: Jessica Pham, Luisa Ladel, Christina Wu, Catriona Jamieson. Leveraging space to advance terrestrial cancer research [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 169.

Treatment with GnRH in a controlled internal drug release (CIDR)-based timed AI protocol induced synchronized follicular wave emergence, a large ovulatory follicle, and synchronous ovulation following a second injection of GnRH, while follicular wave emergence was relatively asynchronous in the estradiol benzoate (EB)-treated cows resulting in ovulation of smaller ovulatory follicles (Kim et al. 2004 Theriogenology, in press). In this study, we compared new follicular wave emergence and follicular development following treatment with EB plus progesterone (P4) or GnRH at the first follicular wave in CIDR-treated, lactating Holstein cows. Previously synchronized, lactating Holstein cows (n = 20) received a CIDR (CIDR™, InterAg, Hamilton, New Zealand, Day 0) 3 to 8 days after ovulation and were randomly assigned to two treatments: cows in the GnRH group (n = 10) received 100 μg fertirelin acetate i.m. (GnRH, Conceral, Dongbang Co., Seoul, Korea) and those in the E/P group (n = 10) received 2 mg EB (SY Esrone, Samyang, Seoul, Korea) and 50 mg P4 i.m. (SY Ovaron, Samyang, Seoul, Korea) at that time. Thereafter, all animals received PGF2α (Lutalyse, Pharmacia & Upjohn, Puurs, Belgium) at the time of CIDR removal on Day 7, and GnRH on Day 9. Ovaries of each cow were examined by transrectal ultrasonography (Sonoace 600 with 5.0 MHz linear-array transducer; Medison Co., Ltd., Seoul, Korea) every 24 h from Days 0 to 9, on Day 11, and on Day 14 of treatment to observe changes in ovarian structures (follicles and CL). Data were analyzed by Fisher's exact test, Wilcoxon Rank-Sum test and Student's t-test using an SAS program. Follicular wave emergence occurred within 7 days in 9/10 GnRH- and 8/10 E/P-treated cows (P > 0.05). The interval to wave emergence was longer (P < 0.01) in the E/P group (5.9 ± 0.5 days) than in the GnRH group (2.9 ± 0.4 days). While diameters of dominant follicles on Day 0 were not different (P > 0.05) between groups, diameters on Day 7 and Day 9 in the E/P group (9.4 ± 0.4 and 13.1 ± 0.7 mm, respectively) were significantly smaller (P < 0.01) than those in the GnRH group (12.9 ± 0.5 and 15.8 ± 0.7 mm, respectively). Growth rates of preovulatory follicles in the E/P group (2.1 ± 0.2 mm/day) were greater (P < 0.01) than in the GnRH group (1.2 ± 0.1 mm/day), while the duration of dominance of the preovulatory follicle was longer (P < 0.01) in the GnRH group (6.3 ± 0.4 days) than in the E/P group (3.3 ± 0.5 days). Synchronized ovulation by 40 h after the GnRH injection (Day 11) occurred in 10/10 GnRH- and 9/10 E/P-treated cows (P > 0.05). Results suggest that estradiol benzoate plus progesterone administered at the first follicular wave in CIDR-treated, lactating Holstein cows delays new follicular wave emergence, resulting in ovulation of smaller ovulatory follicles than GnRH. Endocrine changes during treatment and fertility following timed AI has been investigated in this study.

Treatment with estradiol benzoate (EB), compared to GnRH, in a controlled internal drug release (CIDR)-based timed AI protocol induced relatively asynchronous follicular wave emergence, resulting in ovulation of smaller ovulating follicles (Kim et al. 2005 Theriogenology 63, 260-268). In this study, we compared new follicular wave emergence and development following treatment with EB (2 mg) plus progesterone (50 mg) at a growing (Day 3 after ovulation) or a static (Day 8) phase of the dominant follicle during the first follicular wave in CIDR-treated, lactating dairy cows. Previously synchronized, lactating dairy cows received CIDRs (InterAg, Hamilton, New Zealand; Day 0) 3 days after ovulation and were assigned to two treatment groups and a control group. Cows in the T1 group (n = 11) received 2 mg EB (SY Esrone; Samyang, Seoul, Korea) and 50 mg P4 (SY Ovaron; Samyang) i.m., and those in the control group (n = 10) received no treatment at that time. Other previously synchronized cows received a CIDR (Day 0) with injections of 2 mg EB plus 50 mg P4 i.m. 8 days after ovulation (T2 group, n = 10). Thereafter, all cows received PGF2� (Lutalyse; Pharmacia & Upjohn, Puurs, Belgium) at the time of CIDR removal on Day 7, and GnRH (Conceral; Dongbang Co., Seoul, Korea) on Day 9. Ovaries of each cow were examined by transrectal ultrasonography (Sonoace 600 with 7.5 MHz linear-array transducer; Medison Co., Ltd, Seoul, Korea) every 24 h from Days 0 to 9, on Day 11, and on Day 14 of treatment to observe changes in ovarian structures (follicles and corpora lutea (CL)). Data were analyzed by Fisher's exact test, Kruskal-Wallis test, and ANOVA using an SAS program (SAS Institute, Inc., Cary, NC, USA). Follicular wave emergence occurred within 7 days in 3/10 of the control group, 9/11 of the T1 group, and 9/10 of the T2 group (P < 0.05). The interval to wave emergence did not differ (P > 0.05) among groups (3.7 � 1.2, 4.8 � 0.5, 5.9 � 0.3 days, respectively). While the diameters of dominant follicles on Day 0 were greater (P < 0.01) in the T2 group (14.3 � 1.2 mm) than in the control (9.4 � 0.6 mm) and T1 (10.5 � 0.7 mm) group, diameters of preovulatory follicles on Day 9 were significantly smaller (P < 0.01) in the T1 (13.6 � 0.7 mm) and T2 (12.3 � 0.5 mm) groups than in the control group (16.4 � 0.8 mm). Synchronized ovulation by 40 h after the GnRH injection (Day 11) occurred in 10/10 of the control group, 10/11 of the T1 group, and 9/10 of the T2 group (P > 0.05). In conclusion, administration of 2 mg EB plus 50 mg P4 at both a growing and a static phase of the dominant follicle during the first follicular wave results in synchronous follicular wave emergence and development and also synchronized ovulation in CIDR-treated, lactating dairy cows.

Abstract Multiple Myeloma (MM)-related osteolytic lesions of the skeleton result from asynchronous bone turnover wherein increased bone resorption by osteoclasts (OCLs) is associated to suppression of bone formation due to inhibition of osteoblasts (OBLs). In this context, the balance between osteoprotegerin (OPG) and the receptor activator for nuclear factor-κB ligand (RANKL) plays a relevant role, because RANKL signaling induces differentiation, activation and survival of OCLs, whereas OPG acts as a decoy receptor of RANKL, thus blocking bone resorption. In the MM milieu, the interaction of malignant plasma cells (PCs) and bone marrow stromal cells (BMSCs) favors the production of RANKL and reduces OPG secretion by BMSCs. The resulting severe imbalance in RANKL/OPG ratio is the main trigger of MM-related bone disease (BD). Emerging evidence indicates that microRNAs (miRNAs) play a crucial role in bone remodelling as they can act on bone effectors (OCLs, OBLs, BMSCs) and PCs. Indeed, several findings suggest that miR-29 family support OBL differentiation, while we have previously demonstrated that miR-29b is down-regulated during osteoclastogenesis and its enforced expression functionally inhibits terminally differentiated OCLs. Moreover, also miR-21 plays an important role in OCL differentiation and is up-regulated by IL-6 via STAT3 that, in turn, promotes survival and proliferation of PCs, favoring bone damage. On these bases, we investigated whether modulation of miR-21 expression in BMSCs may have an impact on MM microenviroment, focusing our attention on OPG production, taking into account that different bioinformatics resources indicate OPG mRNA as a predicted target of miR-21. To this end, we established a co-culture system where primary BMSCs and HS-5, a human BMSC cell line, were exposed to either RPMI 8226 MM cells or primary CD138+ PCs isolated from MM patients. Then, we isolated BMSCs and evaluated miR-21 and OPG expression. We observed strong up-regulation of miR-21 in BMSCs and HS-5 together with a significant reduction of OPG levels in the presence of MM cells. These preliminary data suggested that antagonizing miR-21 in BMSCs exposed to MM cells could restore RANKL/OPG ratio through the up-regulation of OPG. To address this hypothesis, we transduced HS-5 cell line with a lentiviral vector carrying anti-miR-21 sequence (a21 HS-5) or with an empty lentiviral vector carrying only the GFP gene (GFP CNT HS-5). OPG expression was determined by RT-PCR, Western Blotting and ELISA assays after 48h and 72h of exposure to RPMI 8226 cells or primary PCs. We observed a significant increase in OPG production in a21 HS-5 cells compared to controls (Fig. 1, panel A and panel B). We also evaluated RANKL expression in the same samples. Interestingly, constitutive inhibition of miR-21 in HS-5 cell line upon exposure to MM cells induced a significant RANKL down-regulation, thus restoring a physiological RANKL/OPG ratio. We hypothesized that this surprising result may be due to the activity of the protein inhibitor of activated STAT3 (PIAS3). Indeed, PIAS3 binds to STAT3 and blocks its DNA binding ability, thereby inhibiting STAT3-mediated gene activation. It is already known that PIAS3 acts as a negative regulator of the RANKL expression and it is a direct and validated target of miR-21. Therefore, the inhibition of miR-21 induces PIAS3 up-regulation and a decreased RANKL transcription. To confirm the involvement of PIAS3 in RANKL suppression in our system, we performed a WB assay, showing that in a21 HS-5 cells, PIAS3 is indeed over-expressed compared to controls. Taken together, these findings provide the first evidence that inhibition of miR-21 in MM microenviroment restores RANKL/OPG balance, which might result in prevention of skeletal- related events. These findings support the design of innovative miR-21 inhibition-based approaches against MM-related BD. Supported by the Italian Association for Cancer Research (AIRC) “Special Program Molecular Clinical Oncology - 5 per mille”, PI:P.T., n. 9980, 2010/15.”Fig.1Fig.1. Disclosures: No relevant conflicts of interest to declare.

Abstract Piezoelectric ultrasonic transducers with the function of energy conversation, as well as their numerous advantages, such as high-power density, quick response, flexible design, and service reliability, are involved in wide applications of industrial processing, precision driving, smart sensing, and medical services. The electromechanical equivalent circuit and Kirchhoff’s law indicate that mechatronics parameters are essential for performance evaluation, reliability analysis, and fault diagnosis of ultrasonic transducers. Importantly, the ultrasonic transducer is a time variant system, data of one single parameter collected from a certain test can’t match with the data of another single parameter acquired from a different test. So, a synchronous and precise online measurement of electronic parameters is encouraged for performance evaluation and optimization design of ultrasonic transducers. With the combination of virtual instrument technology, an asynchronous measurement system of electrical excitation parameters for the ultrasonic transducers of linear driving motors was established in this study. Furthermore, the systematic measurement methods and error theory, including the calculation methods and measuring circuits of electric signals, were illustrated. Experimental results proved that the proposed system and methods for measuring the input electronic power of ultrasonic transducer (e.g., effective value method for voltage and current, energy moment method for frequency, and spectrum analysis method for phase difference) are highly precise, quick responsive, robust, and reliable for ultrasonic transducers. The findings of this study provide valuable references and suggestions for efficient, accurate, and online performance evaluation of ultrasonic transducers, particularly for piezoelectric transducers utilizing ultrasonic high-voltage exciting signals.&#xD;

Abstract The transient load fluctuations on the runner blades of prototype hydraulic turbines during load variations are one of the main causes of fatigue and eventual structural failure. A clear understanding of the dynamic loads on the runner blades is required to detect the source of the fluctuations. In this paper, an experimental investigation of vortex rope formation and mitigation in a prototype Kaplan turbine, namely, Porjus U9, is carried out. Synchronized unsteady pressure and strain measurements were performed on a runner blade during steady-state and load variation under off-cam condition. The normalized pressure fluctuation during load variations remained approximately within ±0.2Pref for all the pressure transducers installed on the blade pressure side and is even slightly lower during the transient cycle. Higher pressure fluctuations were found on the blade suction side, approximately four times higher than that of on the pressure side. The synchronous and asynchronous components of the vortex rope were clearly observed at the low discharge operating point and transient cycles. The spectral analysis of the pressure signals showed that the synchronous component appears before the asynchronous component during the load reduction, and it lasts longer during the load increase. These frequencies slightly change during the load variation. In addition, the results proved that the strain fluctuation component on the runner blade arises from the synchronous component of the vortex rope at low discharge while the asynchronous component influence is negligible.

Abstract This paper presents an indirect method for measuring the mechanical power produced by three-phase induction motors. The proposed technique is based on the hypothesis that three-phase induction motors are balanced systems that transform electrical power into mechanical one. The measurement of a single phase current is used to estimate the mechanical power generated at the axis. The relationship between electric current and mechanical power is generally non-linear. By expressing the quantities in p.u., this trend is approximated with a second order polynomial. From the analysis of the mechanical power characteristics related to 13 motors we obtained the parameters of the interpolating parabolic curves of motors from 1.1 kW to 75 kW rated power. The proposed technique can be easily adopted in order to monitor the mechanical power of three phase induction motors using only one phase current transducer. Starting from the motor nameplate no experimental measurement or other data are necessary to estimate the mechanical power. This technique can be widely used in low cost multipoint measurement system able to monitor the mechanical power where no other transducer or voltage divider are necessary.

Abstract Transmission of acoustic signals between distributed sensor nodes may be useful for status monitoring of elongated structures such as pipelines. In principle, coded signals can be used in an asynchronous multiplexed system, provided the signals are distinguishable. However, multimode effects complicate signal propagation, so any such codes should be short. A search for polyphase code families with properties suitable for acoustic code division multiple access (CDMA) is presented. Algorithms for reduction of search space to allow use of a laptop for code discovery are described. Short codes of base 6 are shown to outperform codes of bases 2, 3, 4 and sets suitable for systems with 2 and 3 users are identified. The codes have similar properties to Barker codes but larger sidelobes. Their use is demonstrated by simulation and experiment at kHz frequencies using an air-filled copper pipe, an electromagnetic acoustic transducer (EMAT) and a microphone designed to excite and detect the L(0,1) mode. Low loss propagation over 25 m is achieved with a 20 kHz carrier. Excellent agreement between experiment and theory is demonstrated, with performance limited by transducer bandwidth.

Background: We have previously demonstrated that TBX18 suffices to reprogram postnatal ventricular cardiomyocytes to induced pacemaker cells (TBX18-iPMs). However, the nascent automaticity appeared to wane over time, characterized by loss of syncytial pacing but preservation of single cell automaticity. Hypothesis: Based on increase in Tgfβ ligands in TBX18-iPMs and the known role of Tgfβ signaling in electrical remodeling, we hypothesized that loss of syncytial automaticity is due to electrical decoupling of the iPMs mediated by Tgfβ signaling. Methods: Adenoviral vectors expressing either human TBX18 or GFP were used for gene transfer into neonatal rat ventricular myocytes (NRVMs) or adult rat ventricular myocardium in vivo. Results: NRVM monolayers transduced with GFP were mostly quiescent, interspersed by paroxysmal contractions. In contrast, TBX18 transduced NRVM monolayers showed spontaneous and rhythmic contractions, but the syncytial pacing wavered over the next 5-7 days although numerous iPMs continued to beat asynchronously. Treatment of TBX18-iPMs with an inhibitor of Tgfβ receptors, A83-01, preserved syncytial pacing, suggesting that electrical remodeling cues from Tgfβ signaling led to loss of iPM-iPM electrical coupling. We examined the molecules that are integral to the function of gap junction in the myocardium, namely Cx43, N-cadherin and β-catenin. Cx43 and N-cadherin were downregulated in TBX18-iPMs compared to control by 77±16% and 43±11% (p<0.01, n=6), respectively. Total β-catenin protein level was unaltered, but its distribution decreased at the sarcolemmal and increased in the nuclei of TBX18-iPMs compared to control. Inhibition of Tgfβ with A83-01 restored Cx43 protein level in TBX18-iPMs (2.2-folds higher) compared to untreated TBX18-iPMs. Similarly, adult rats that received intramyocardial injection of TBX18 showed increased Cx43 expression at the boundary between the iPMs and the host myocardium when the animals were treated with systemic delivery of A83-01 for one week compared to TBX18 animals treated with DMSO. Conclusions: TBX18 activates Tgfβ signaling which suppresses cell-cell electrical coupling. Inhibition of Tgfβ signaling in TBX18-iPMs preserves gap junction components and syncytial pacing.

This study discusses the synthesis and use of a new library of spirooxindole-benzimidazole compounds as inhibitors of the signal transducer and activator of p53, a protein involved in regulating cell growth and cancer prevention. The text includes the scientific details of the [3 + 2] cycloaddition (32CA) reaction between azomethine ylide 7a and ethylene 3a within the framework of Molecular Electron Density Theory. The mechanism of the 32CA reaction proceeds through a two-stage one-step process, with emphasis on the highly asynchronous transition state structure. The anti-cancer properties of the synthesized compounds, particularly 6a and 6d, were evaluated. The inhibitory effects of these compounds on the growth of tumor cells (MDA-MB 231 and PC-3) were quantified using IC50 values. This study highlights activation of the p53 pathway by compounds 6a and 6d, leading to upregulation of p53 expression and downregulation of cyclin D and NF-κB in treated cells. Additionally, we explored the binding affinity of spirooxindole analogs, particularly compound 6d, to MDM2, a protein involved in regulation of p53. The binding mode and position of compound 6d were compared with those of a co-crystallized standard ligand, suggesting its potential as a lead compound for further preclinical research.

Abstract The article illustrates the results of an exploratory study on the effectiveness of maximum likelihood Bayesian estimation in the identification of cavitation instabilities in axial inducers using the blade-to-blade pressure measured by a single transducer flush-mounted on the impeller casing. The typical azimuthal distribution of the pressure in the blade channels is parameterized and modulated in space and time for theoretically reproducing the expected pressure generated by known forms of cavitation instabilities (cavitation surge auto-oscillations, n-lobed synchronous/asynchronous rotating cavitation, higher-order surge/rotating cavitation modes). The power spectra of the theoretical pressure so obtained in the rotating frame are transformed in the stationary frame, corrected for frequency broadening effects, and parametrically fitted by maximum likelihood estimation to the measurements of the pressure on the inducer casing just downstream of the blade leading edges. In addition to its fundamental frequency, each form of instability generates a characteristic spectral distribution of sidebands. The identification uses this information for successfully discriminating flow oscillation modes occurring simultaneously with intensities differing by up to one order of magnitude. The method returns the estimates of the model parameters and their standard errors, allowing one to assess the accuracy and statistical significance of the identification. The results first demonstrate that elementary maximum likelihood Bayesian identification is indeed capable to effectively detect and characterize the occurrence of flow instabilities in cavitating inducers at a fraction of the experimental and post-processing costs and complexities of traditional cross-correlation methods.

Background: Ultrasound can interact with tissue through either thermal or non-thermal physical mechanisms. Radiation force has been shown to stimulate cardiac and neural tissue in vivo. Ultrasound might hold clinical potential as a noninvasive therapeutic tool via specific bioeffects on cardiomyocytes. This study aims to assess the effect of ultrasound on cardiomyocyte depolarization in a tissue culture model. Methods: Cardiomyocytes were isolated from neonatal rat ventricular tissue and plated directly on microelectrode arrays to record depolarization patterns. A custom 2.5 MHz unfocused ultrasound transducer was directed at the cardiomyocytes in a tissue culture model. A function generator, with an amplified signal +50 dB, delivered acoustic energy at variable settings of 0.1, 0.3, 0.5 and 1.0 Vpp, pulse durations of 2, 5 and 10 ms, and burst periods of 100, 250 and 300 ms. Five trials were conducted at each setting (36 total trials) with 30s of continuous ultrasound exposure followed by an off interval of 1 minute. Results: The R-R interval durations (ID) were measured throughout the recording period. Prior to ultrasound delivery, the IDs were highly irregular, ID range = 0.3-2.7 s. As ultrasound was delivered in an asynchronous manner, using 0.1 and 0.3 Vpp and PD = 2 and 5 ms, there was suppression/inhibition of cellular depolarization for the first 5-10 s. Then 10-15 s after the start of ultrasound delivery, the depolarization rate increased and demonstrated less R-R interval variability (ID=0.88-1.03 s, P value<0.05), even after the ultrasound exposure. Conclusion: Ultrasound can inhibit and modify the frequency of spontaneous electrical depolarizations of neonatal ventricular cardiomyocytes in a tissue culture model. Our observations could be due to conditioning via stretch and compression-mediated mechanosensitive pathways, by modifying intracellular calcium handling or altering cell signaling.

IntroductionThis short article examines contemporary artistic use of walkie-talkies across two projects: Saturday (2002) by Sabrina Raaf and Walk That Sound (2014) by Lukatoyboy. Drawing on Dominic Pettman’s notion of sonic intimacy, I argue that both artists incorporate walkie-talkies as part of their explorations of mediated wandering, and in ways that seek to capture sonic ambiances and intimacies. One thing that is striking about both these works is that they rethink what’s possible with walkie-talkies; both artists use them not just as low-tech, portable devices for one-to-one communication over distance, but also—and more strikingly—as (covert) recording equipment for capturing, while wandering, snippets of intimate conversation between passers-by and the “voice” of the surrounding environment. Both artworks strive to make the familiar strange. They prompt us to question our preconceived perceptions of, and affective engagements with, the people and places around us, to listen more attentively to the voices of others (and the “Other”), and to aurally inhabit in new ways the spaces and places we find ourselves in and routinely pass through.The walkie-talkie is an established, simple communication device, consisting of a two-way radio transceiver with a speaker and microphone (in some cases, the speaker is also used as the microphone) and an antenna (Wikipedia). Walkie-talkies are half-duplex communication devices, meaning that they use a single radio channel: only one radio on the channel can transmit at a time, but many can listen; when a user wishes to talk, they must turn off the receiver and turn on the transmitter by pressing a push-to-talk button (Wikipedia). In some models, static—known as squelch—is produced each time the push-to-talk button is depressed. The push-to-talk button is a feature of both projects: in Saturday, it transforms the walkie-talkie into a cheap, portable recorder-transmitter. In Walk That Sound, rapid fire exchanges of conversation using the push-to-talk button feature strongly.Interestingly, walkie-talkies were developed during World War Two. While they continue to be used within certain industrial settings, they are perhaps best known as a “quaint” household toy and “fun tool” (Smith). Early print ads for walkie-talkie toys marketed them as a form of both spyware for kids (with the Gabriel Toy Co. releasing a 007-themed walkie-talkie set) and as a teletechnology for communication over distance—“how thrilling to ‘speak through space!’”, states one ad (Statuv “New!”). What is noteworthy about these early ads is that they actively promote experimental use of walkie-talkies. For instance, a 1953 ad for Vibro-Matic “Space Commander” walkie-talkies casts them as media transmission devices, suggesting that, with them, one can send and receive “voice – songs – music” (Statuv “New!”). In addition, a 1962 ad for the Knight-Kit walkie-talkie imagines “you’ll find new uses for this exciting walkie-talkie every day” (Statuv “Details”). Resurgent interest in walkie-talkies has seen them also promoted more recently as intimate tools “for communication without asking permission to communicate” (“Nextel”); this is to say that they have been marketed as devices for synchronous or immediate communication that overcome the limits of asynchronous communication, such as texting, where there might be substantial delays between the sending of a message and receipt of a response. Within this context, it is not surprising that Snapchat and Instagram have also since added “walkie-talkie” features to their messaging services. The Nextel byline, emphasising “without asking permission”, also speaks to the possibilities of using walkie-talkies as rudimentary forms of spyware.Within art practice that explores mediated forms of wandering—that is, walking while using media and various “remote transmission technologies” (Duclos 233)—walkie-talkies hold appeal for a number of reasons, including their particular aesthetic qualities, such as the crackling or static sound (squelch) that one encounters when using them; their portability; their affordability; and, the fact that, while they can be operated on multiple channels, they tend to be regarded primarily as devices that permit two-way, one-to-one (and therefore intimate, if not secure) remote communication. As we will see below, however, contemporary artists, such as the aforementioned earlier advertisers, have also been very attentive to the device’s experimental possibilities. Perhaps the best known (if possibly apocryphal) example of artistic use of walkie-talkies is by the Situationist International as part of their explorations in urban wandering (a revolutionary strategy called dérive). In the Situationist text from 1960, Die Welt als Labyrinth (Anon.), there is a detailed account of how walkie-talkies were to form part of a planned dérive, which was organised by the Dutch section of the Situationist International, through the city of Amsterdam, but which never went ahead:Two groups, each containing three situationists, would dérive for three days, on foot or eventually by boat (sleeping in hotels along the way) without leaving the center of Amsterdam. By means of the walkie-talkies with which they would be equipped, these groups would remain in contact, with each other, if possible, and in any case with the radio-truck of the cartographic team, from where the director of the dérive—in this case Constant [Nieuwenhuys]—moving around so as to maintain contact, would define their routes and sometimes give instructions (it was also the director of the dérive’s responsibility to prepare experiments at certain locations and secretly arranged events.) (Anon.) This proposed dérive formed part of Situationist experiments in unitary urbanism, a process that consisted of “making different parts of the city communicate with one another.” Their ambition was to create new situations informed by, among other things, encounters and atmospheres that were registered through dérive in order to reconnect parts of the city that were separated spatially (Lefebvre quoted in Lefebvre and Ross 73). In an interview with Kristin Ross, Henri Lefebvre insists that the Situationists “did have their experiments; I didn’t participate. They used all kinds of means of communication—I don’t know when exactly they were using walkie-talkies. But I know they were used in Amsterdam and in Strasbourg” (Lefebvre quoted in Lefebvre and Ross 73). However, as Rebecca Duclos points out, such use “is, in fact, not well documented”, and “none of the more well-known reports on situationist activity […] specifically mentions the use of walkie-talkies within their descriptive narratives” (Duclos 233). In the early 2000s, walkie-talkies also figured prominently, alongside other media devices, in at least two location-based gaming projects by renowned British art collective Blast Theory, Can You See Me Now? (2001) and You Get Me (2008). In the first of these projects, participants in the game (“online players”) competed against members of Blast Theory (“runners”), tracking them through city streets via a GPS-enabled handheld computer that runners carried with them. The goal for online players was to move an avatar they created through a virtual map of the city as multiple runners “pursued their avatar’s geographical coordinates in real-time” (Leorke). As Dale Leorke explains, “Players could see the locations of the runners and other players and exchange text messages with other players” (Leorke 27), and runners could “read players’ messages and communicate directly with each other through a walkie-talkie” (28). An audio stream from these walkie-talkie conversations allowed players to eavesdrop on their pursuers (Blast Theory, Can You See Me Now?).You Get Me was similarly structured, with online players and “runners” (eight teenagers who worked with Blast Theory on the game). Remotely situated online players began the game by listening to the “personal geography” of the runners over a walkie-talkie stream (Blast Theory, You Get Me). They then selected one runner, and tracked them down by navigating their own avatar, without being caught, through a virtual version of Mile End Park in London, in pursuit of their chosen runner who was moving about the actual Mile End Park. Once their chosen runner was contacted, the player had to respond to a question that the runner posed to them. If the runner was satisfied with the player’s answer, conversation switched to “the privacy of a mobile phone” in order to converse further; if not, the player was thrown back into the game (Blast Theory, You Get Me). A key aim of Blast Theory’s work, as I have argued elsewhere (Wilken), is the fostering of interactions and fleeting intimacies between relative and complete strangers. The walkie-talkie is a key tool in both the aforementioned Blast Theory projects for facilitating these interactions and intimacies.Beyond these well-known examples, walkie-talkies have been employed in productive and exploratory ways by other artists. The focus in this article is on two specific projects: the first by US-based sound artist Sabrina Raaf, called Saturday (2002) and the second by Serbian sound designer Lukatoyboy (Luka Ivanović), titled Walk That Sound (2014). Sonic IntimaciesThe concept that gives shape and direction to the analysis of the art projects by Raaf and Lukatoyboy and their use of walkie-talkies is that of sonic intimacy. This is a concept of emerging critical interest across media and sound studies and geography (see, for example, James; Pettman; Gallagher and Prior). Sonic intimacy, as Dominic Pettman explains, is composed of two simultaneous yet opposing orientations. On the one hand, sonic intimacy involves a “turning inward, away from the wider world, to more private and personal experiences and relationships” (79). While, on the other hand, it also involves a turning outward, to seek and heed “the voice of the world” (79)—or what Pettman refers to as the “vox mundi” (66). Pettman conceives of the “vox mundi” as an “ecological voice”, whereby “all manner of creatures, agents, entities, objects, and phenomena” (79) have the opportunity to speak to us, if only we were prepared to listen to our surroundings in new and different ways. In a later passage, he also refers to the “vox mundi” as a “carrier or potentially enlightening alterity” (83). Voices, Pettman writes, “transgress the neat divisions we make between ‘us’ and ‘them’, at all scales and junctures” (6). Thus, Pettman’s suggestion is that “by listening to the ‘voices’ that lie dormant in the surrounding world […] we may in turn foster a more sustainable relationship with [the] local matrix of specific existences” (85), be they human or otherwise.This formulation of sonic intimacy provides a productive conceptual frame for thinking through Raaf’s and Lukatoyboy’s use of walkie-talkies. The contention in this article is that these two projects are striking for the way that they both use walkie-talkies to explore, simultaneously, this double articulation or dual orientation of sonic intimacy—a turning inwards to capture more private and personal experiences and conversations, and a turning outwards to capture the vox mundi. Employing Pettman’s notion of sonic intimacy as a conceptual frame, I trace below the different ways that these two projects incorporate walkie-talkies in order to develop mediated forms of wandering that seek to capture place-based sonic ambiances and sonic intimacies.Sabrina Raaf, Saturday (2002)US sound artist Sabrina Raaf’s Saturday (2002) is a sound-based art installation based on recordings of “stolen conversations” that Raaf gathered over many Saturdays in Humboldt Park, Chicago. Raaf’s work harks back to the early marketing of walkie-talkie toys as spyware. In Raaf’s hands, this device is used not for engaging in intimate one-to-one conversation, but for listening in on, and capturing, the intimate conversations of others. In other words, she uses this device, as the Nextel slogan goes, for “communication without permission to communicate” (“Nextel”). Raaf’s inspiration for the piece was twofold. First, she has noted that “with the overuse of radio frequency bands for wireless communications, there comes the increased occurrence of crossed lines where a private conversation becomes accidentally shared” (Raaf). Reminiscent of Francis Ford Coppola’s film The Conversation (1974), in which surveillance expert Harry Caul (Gene Hackman) records the conversation of a couple as they walk through crowded Union Square in San Francisco, Raaf used a combination of walkie-talkies, CB radios, and “various other forms of consumer spy […] technology in order to actively harvest such communication leaks” (Raaf). The second source of inspiration was noticing the “sheer quantity of non-phone, low tech, radio transmissions that were constantly being sent around [the] neighbourhood”, transmissions that were easily intercepted. These conversations were eclectic in composition and character:The transmissions included communications between gang members on street corners nearby and group conversations between friends talking about changes in the neighbourhood and their families. There were raw, intimate conversations and often even late night sex talk between potential lovers. (Raaf)What struck Raaf about these conversations, these transmissions, was that there was “a furtive quality” to most of them, and “a particular daringness to their tone”.During her Saturday wanderings, Raaf complemented her recordings of stolen snippets of conversation with recordings of the “voice” of the surrounding neighbourhood—“the women singing out their windows to their radios, the young men in their low rider cars circling the block, the children, the ice cream carts, etc. These are the sounds that are mixed into the piece” (Raaf).Audience engagement with Saturday involves a kind of austere intimacy of its own that seems befitting of a surveillance-inspired sonic portrait of urban and private life. The piece is accessed via an interactive glove. This glove is white in colour and about the size of a large gardening glove, with a Velcro strap that fastens across the hand, like a cycling glove. The glove, which only has coverings for thumb and first two fingers (it is missing the ring and little fingers) is wired into and rests on top of a roughly A4-sized white rectangular box. This box, which is mounted onto the wall of an all-white gallery space at the short end, serves as a small shelf. The displayed glove is illuminated by a discrete, bent-arm desk lamp, that protrudes from the shelf near the gallery wall. Above the shelf are a series of wall-mounted colour images that relate to the project. In order to hear the soundtrack of Saturday, gallery visitors approach the shelf, put on the glove, and “magically just press their fingertips to their forehead [to] hear the sound without the use of their ears” (Raaf). The glove, Raaf explains, “is outfitted with leading edge audio electronic devices called ‘bone transducers’ […]. These transducers transmit sound in a very unusual fashion. They translate sound into vibration patterns which resonate through bone” (Raaf).Employing this technique, Raaf explains, “permits a new way of listening”:The user places their fingers to their forehead—in a gesture akin to Rodin’s The Thinker or of a clairvoyant—in order to tap into the lives of strangers. Pressing different combinations of fingers to the temple yield plural viewpoints and group conversations. These sounds are literally mixed in the bones of the listener. (Raaf) The result is a (literally and figuratively) touching sonic portrait of Humboldt Park, its residents, and the “voice” of its surrounding neighbourhoods. Through the unique technosomatic (Richardson) apparatus—combinations of gestures that convey the soundscape directly through the bones and body—those engaging with Saturday get to hear voices in/of/around Humboldt Park. It is a portrait that combines sonic intimacy in the two forms described earlier in this article. In its inward-focused form, the gallery visitor-listener is positioned as a voyeur of sorts, listening into stolen snippets of private and personal relationships, experiences, and interactions. And, in its outward-focused form, the gallery visitor-listener encounters a soundscape in which an array of agents, entities, and objects are also given a voice. Additional work performed by this piece, it seems to me, is to be found in the intermingling of these two form of sonic intimacy—the personal and the environmental—and the way that they prompt reflection on mediation, place, urban life, others, and intimacy. That is to say that, beyond its particular sonic portrait of Humboldt Park, Saturday works in “clearing some conceptual space” in the mind of the departing gallery visitor such that they might “listen for, if not precisely to, the collective, polyphonic ‘voice of the world’” (Pettman 6) as they go about their day-to-day lives.Lukatoyboy, Walk That Sound (2014)The second project, Walk That Sound, by Serbian sound artist Lukatoyboy was completed for the 2014 CTM festival. CTM is an annual festival event that is staged in Berlin and dedicated to “adventurous music and art” (CTM Festival, “About”). A key project within the festival is CTM Radio Lab. The Lab supports works, commissioned by CTM Festival and Deutschlandradio Kultur – Hörspiel/Klangkunst (among other partnering organisations), that seek to pair and explore the “specific artistic possibilities of radio with the potentials of live performance or installation” (CTM Festival, “Projects”). Lukatoyboy’s Walk That Sound was one of two commissioned pieces for the 2014 CTM Radio Lab. The project used the “commonplace yet often forgotten walkie-talkie” (CTM Festival, “Projects”) to create a moving urban sound portrait in the area around the Kottbusser Tor U-Bahn station in Berlin-Kreuzberg. Walk That Sound recruited participants—“mobile scouts”—to rove around the Kottbusser Tor area (CTM Festival, “Projects”). Armed with walkie-talkies, and playing with “the array of available and free frequencies, and the almost unlimited amount of users that can interact over these different channels”, the project captured the dispatches via walkie-talkie of each participant (CTM Festival, “Projects”). The resultant recording of Walk That Sound—which was aired on Deutschlandradio (see Lukatoyboy), part of a long tradition of transmitting experimental music and sound art on German radio (Cory)—forms an eclectic soundscape.The work juxtaposes snippets of dialogue shared between the mobile scouts, overheard mobile phone conversations, and moments of relative quietude, where the subdued soundtrack is formed by the ambient sounds—the “voice”—of the Kottbusser Tor area. This voice includes distant traffic, the distinctive auditory ticking of pedestrian lights, and moments of tumult and agitation, such as the sounds of construction work, car horns, emergency services vehicle sirens, a bottle bouncing on the pavement, and various other repetitive yet difficult to identify industrial sounds. This voice trails off towards the end of the recording into extended walkie-talkie produced static or squelch. The topics covered within the “crackling dialogues” (CTM Festival, “Projects”) of the mobile scouts ranged widely. There were banal observations (“I just stepped on a used tissue”; “people are crossing the street”; “there are 150 trains”)—wonderings that bear strong similarities with French writer Georges Perec’s well-known experimental descriptions of everyday Parisian life in the 1970s (Perec “An Attempt”). There were also intimate, confiding, flirtatious remarks (“Do you want to come to Turkey with me?”), as well as a number of playfully paranoid observations and quips (“I like to lie”; “I can see you”; “do you feel like you are being recorded?”; “I’m being followed”) that seem to speak to the fraught history of Berlin in particular as well as the complicated character of urban life in general—as Pettman asks, “what does ‘together’ signify in a socioeconomic system so efficient in producing alienation and isolation?” (92).In sum, Walk That Sound is a strangely moving exploration of sonic intimacy, one that shifts between many different registers and points of focus—much like urban wandering itself. As a work, it is variously funny, smart, paranoid, intimate, expansive, difficult to decipher, and, at times, even difficult to listen to. Pettman argues that, “thanks in large part to the industrialization of the human ear […], we have lost the capacity to hear the vox mundi, which is […] the sum total of cacophonous, heterogeneous, incommensurate, and unsynthesizable sounds of the postnatural world” (8). Walk That Sound functions almost like a response to this dilemma. One comes away from listening to it with a heightened awareness of, appreciation for, and aural connection to the rich messiness of the polyphonic contemporary urban vox mundi. ConclusionThe argument of this article is that Sabrina Raaf’s Saturday and Lukatoyboy’s Walk That Sound are two projects that both incorporate walkie-talkies in order to develop mediated forms of wandering that seek to capture place-based sonic ambiances and sonic intimacies. Drawing on Pettman’s notion of “sonic intimacy”, examination of these projects has opened consideration around voice, analogue technology, and what Nick Couldry refers to as “an obligation to listen” (Couldry 580). In order to be heard, Pettman remarks, and “in order to be considered a voice at all”, and therefore as “something worth heeding”, the vox mundi “must arrive intimately, or else it is experienced as noise or static” (Pettman 83). In both the projects discussed here—Saturday and Walk That Sound—the walkie-talkie provides this means of “intimate arrival”. As half-duplex communication devices, walkie-talkies have always fulfilled a double function: communicating and listening. This dual functionality is exploited in new ways by Raaf and Lukatoyboy. In their projects, both artists turn the microphone outwards, such that the walkie-talkie becomes not just a device for communicating while in the field, but also—and more strikingly—it becomes a field recording device. The result of which is that this simple, “playful” communication device is utilised in these two projects in two ways: on the one hand, as a “carrier of potentially enlightening alterity” (Pettman 83), a means of encouraging “potential encounters” (89) with strangers who have been thrown together and who cross paths, and, on the other hand, as a means of fostering “an environmental awareness” (89) of the world around us. In developing these prompts, Raaf and Lukatoyboy build potential bridges between Pettman’s work on sonic intimacy, their own work, and the work of other experimental artists. For instance, in relation to potential encounters, there are clear points of connection with Blast Theory, a group who, as noted earlier, have utilised walkie-talkies and sound-based and other media technologies to explore issues around urban encounters with strangers that promote reflection on ideas and experiences of otherness and difference (see Wilken)—issues that are also implicit in the two works examined. In relation to environmental awareness, their work—as well as Pettman’s calls for greater sonic intimacy—brings renewed urgency to Georges Perec’s encouragement to “question the habitual” and to account for, and listen carefully to, “the common, the ordinary, the infraordinary, the background noise” (Perec “Approaches” 210).Walkie-talkies, for Raaf and Lukatoyboy, when reimagined as field recording devices as much as remote transmission technologies, thus “allow new forms of listening, which in turn afford new forms of being together” (Pettman 92), new forms of being in the world, and new forms of sonic intimacy. Both these artworks engage with, and explore, what’s at stake in a politics and ethics of listening. Pettman prompts us, as urban dweller-wanderers, to think about how we might “attend to the act of listening itself, rather than to a specific sound” (Pettman 1). His questioning, as this article has explored, is answered by the works from Raaf and Lukatoyboy in effective style and technique, setting up opportunities for aural attentiveness and experiential learning. However, it is up to us whether we are prepared to listen carefully and to open ourselves to such intimate sonic contact with others and with the environments in which we live.ReferencesAnon. “Die Welt als Labyrinth.” Internationale Situationiste 4 (Jan. 1960). International Situationist Online, 19 June 2019 <https://www.cddc.vt.edu/sionline/si/diewelt.html>Blast Theory. “Can You See Me Now?” Blast Theory, 19 June 2019 <https://www.blasttheory.co.uk/projects/can-you-see-me-now/>.———. “You Get Me.” Blast Theory, 19 June 2019 <https://wwww.blasttheory.co.uk/projects/you-get-me/>.Cory, Mark E. “Soundplay: The Polyphonous Tradition of German Radio Art.” Wireless Imagination: Sound, Radio, and the Avant-garde. Eds. Douglas Kahn and Gregory Whitehead. 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