Newborn Incubators Do Not Protect from High Noise Levels in the Neonatal Intensive Care Unit and Are Relevant Noise Sources by Themselves

Background: While meaningful sound exposure has been shown to be important for newborn development, an excess of noise can delay the proper development of the auditory cortex. Aim: The aim of this study was to assess the acoustic environment of a preterm baby in an incubator on a newborn intensive care unit (NICU). Methods: An empty but running incubator (Giraffe Omnibed, GE Healthcare) was used to evaluate the incubator frequency response with 60 measurements. In addition, a full day and night period outside and inside the incubator at the NICU of the University Hospital Zurich was acoustically analyzed. Results: The fan construction inside the incubator generates noise in the frequency range of 1.3–1.5 kHz with a weighted sound pressure level (SPL) of 40.5 dB(A). The construction of the incubator narrows the transmitted frequency spectrum of sound entering the incubator to lower frequencies, but it does not attenuate transient noises such as alarms or opening and closing of cabinet doors substantially. Alarms, as generated by the monitors, the incubator, and additional devices, still pass to the newborn. Conclusions: The incubator does protect only insufficiently from noise coming from the NICUThe transmitted frequency spectrum is changed, limiting the impact of NICU noise on the neonate, but also limiting the neonate’s perception of voices. The incubator, in particular its fan, as well as alarms from patient monitors are major sources of noise. Further optimizations with regard to the sound exposure in the NICU, as well as studies on the role of the incubator as a source and modulator, are needed to meet the preterm infants’ multi-sensory needs.

A High-Frequency Surface Wave Radar Simulation Using FMCW Technique for Ship Detection

Indonesia is an archipelagic country with a vast sea area. This vast sea area becomes a challenge in conducting regional surveillance to maintain maritime conditions. The use of buoys and satellites still has shortcomings in carrying out surveillance despite its excellent surveillance capabilities. A high-frequency radar technology with 3-30 MHz frequency and surface wave propagation are very suitable because it has a radar range that can cross the horizon or commonly refer to as Over the Horizon (OTH). The Frequency Modulated Continuous Wave (FMCW) technique on this radar obtains distance and velocity information by a continuously transmitted frequency modulation. The use of radar in Indonesia for marine surveillance is still infrequent. Therefore, it is relatively difficult to conduct testing and obtain data. In addition, the direct examination requires extended time, so a simulation program is needed. This paper discusses the design of a High-Frequency Surface Wave Radar (HFSWR) simulation program using FMCW modulation technique. The simulation program detected two objects based on time delays due to the distance and velocity of the object with a maximum range of 350 km. It displayed the results in an informative manner. The object detection was based on the results of the Fast Fourier Transform (FFT) from the mixed signals. The mixed signal is a combination of transmitted signal and reflected signal in which there are time delay components due to the object. The simulation program had been tested with input values of distance and velocity that vary, both for one object and two objects, in the radial direction. It generated output that was close to the input value with a level of accuracy of ± 2 km.

Improving the accuracy of the time and frequency signal transmission over coaxial cable

This paper assesses the effect of wide temperature differences of cable segments on the stability of the transmitted frequency. Paper presents a method for determining the integral temperature of a long cable, as well as a method for compensating the introduced instability of the transmitted frequency. A method for stabilizing the integral temperature of a long coaxial cable using a proportional-integral-differentiating algorithm (PID) algorithm and a distributed heater is also proposed.

Dynamic Model Development and Analysis of Multiple Rotors Coupled With Thrust Collars

The core model of integrally geared centrifugal compressor/expander equipped with thrust collars is developed using finite element model. Each rotor model is coupled through the equivalent stiffness due to thrust collar and the gear web. Subsynchronous vibration caused by the transmitted frequency components from other shafts is analyzed through forced vibration analysis. Unlike conventional frequency response function (FRF), directional FRF technique is adopted because rotordynamic analysis requires that forward and backward mode responses should be identified according to the rotational force direction exerted on the rotor. Previous analysis results utilizing 3D FE model of geared rotors equipped with thrust collars revealed that transmitted vibration level is mostly affected by thrust collars, rather than gear tooth. The rotordynamic model developed in this paper ensures reliability and efficiency in the multi-rotor design equipped with thrust collars providing a systematic way to analyze the multi-rotor vibration responses due to the transmitted forces from one shaft to the other.

Time-frequency tomographic imaging of a rotating object in a narrow-band radar

The backscatter from radar object carries Doppler information of scatterers on the object determined by the radial velocity of scattering points and the radar transmitted frequency. For a rotating object this information is contained in the frequency characteristics over varying aspect angle. Frequency characteristics are used to create projections for Doppler radar tomographic imaging. This paper presents a method for high resolution imaging of a rotating target using a time-frequency transform of a returned signal as tomographic projections. The resolution of a tomographic image depends not only on radar system parameters but also depends on the resolution of input projections. The reassigned spectrogram is proposed for building of tomographic projections, due to its possibility of squeezing of frequency spread. The reassigned spectrogram is sensitive to noise so the denoising procedure in the time-frequency domain must be performed before the reassignment procedure. The denoising is performed by removing Short Time Fourier Transform (STFT) noise coefficients below the appropriate threshold. The STFT is a linear time-frequency transform and coefficients, which belong to the signal and coefficients which belong to noise can be analyzed separately. The efficiency of the proposed idea of imaging is supported by results of numerical experiments.

Research on the Applications and Measurements of the Microwave Technology

Microwave technology is extensively used for point-to-point telecommunications. Microwaves are especially suitable for this use since they are more easily focused into narrower beams than radio waves, allowing frequency reuse; their comparatively higher frequencies allow broad bandwidth and high data transmission rates, and antenna sizes are smaller than at lower frequencies because antenna size is inversely proportional to transmitted frequency. Microwaves are used in spacecraft communication, and much of the world’s data, TV, and telephone communications are transmitted long distances by microwaves between ground stations and communications satellites. Microwaves are also employed in microwave ovens and in radar technology. The prefix “micro-” in “microwave” indicates that microwaves are “small” compared to waves used in typical radio broadcasting, in that they have shorter wavelengths. The boundaries between far infrared light, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study.

Errors Caused by Long-Term Drifts of Magnetron Frequencies for Refractivity Measurement with a Radar: Theoretical Formulation and Initial Validation

Refractivity measurements in the boundary layer by precipitation radar could be useful for convection prediction. Until now such measurements have only been performed by coherent radars, but European weather radars are mostly equipped with noncoherent magnetron transmitters for which the phase and frequency may vary. In this paper, the authors give an analytical expression of the refractivity measurement by a noncoherent drifting-frequency magnetron radar and validate it by comparing with in situ measurements. The main conclusion is that, provided the necessary corrections are applied, the measurement can be successfully performed with a noncoherent radar. The correction factor mainly depends on the local-oscillator frequency variation, which is known perfectly. A second-order error, proportional to the transmitted frequency variation, can be neglected as long as this change remains small.

Wireless Instrumentation for Monitoring of Smart Structures

Smart structures needs lots of sensor installation to sense their status and also the external environmental change. Wireless technique can give a good solution to install sensors without heavy cables. So, in this work, a wireless device was developed to transmit static strain and elastic wave propagation of structures. The specification of this device was as follows: 2.4 GHz of transmitted frequency, 8 channels, 57,600 bps of the transmitted speed, and 10 mW of the transmitted power. In order to confirm the wireless device’s feasibility, a beam test was performed with five optical fiber strain sensors and two piezo-ceramic sensors with the wireless instrumentation.

GEM‐2A: A programmable broadband helicopter‐towed electromagnetic sensor

We present a new helicopter‐towed broadband electromagnetic sensor, GEM‐2A, for mineral prospecting and geologic mapping. The sensor uses one set of transmitter and receiver coils for a multifrequency operation. For a given survey, the user initially specifies a set of operational frequencies in the current bandwidth of 90 Hz to 48 kHz. The transmitter coil then emanates a current waveform that contains all specified frequencies. The duration of this current waveform, called the base period, is typically 1/30 s (a submultiple of local powerline frequency) resulting in an overall data rate at 30 Hz. Receiver channels digitize the secondary field into a time series over a base period, which is then subjected to discrete sine and cosine transforms or convolutions at each transmitted frequency to produce the raw in‐phase and quadrature data. Additional convolutions may be included for passively monitoring environmental noise, including powerline emissions. The entire operation, including the system upload/download and realtime monitoring and communication, is done in Microsoft Windows. The fact that the sensor contains only a single set of coils for the broadband operation provides several unique advantages, some of which include (1) co‐relatable and coherent drift characteristics among frequencies, (2) spectral integrity among frequencies that may be useful for anomaly classification and, possibly, mineral discrimination, (3) tolerance to sferics, (4) tolerance to powerline noise, and (5) light tow body with minimal cockpit hardware suitable for a small helicopter. This paper presents the sensor construction, operation, and data examples.