A computerized system based on an alternative pulse echo immersion technique for acoustic characterization of non-porous solid tissue mimicking materials

This paper discusses the development of a computerized acoustic characterization system of non-porous solid tissue mimicking materials. This system employs an alternative pulse echo immersion technique and consists of a pulser/receiver generator, a transducer used as both a transmitter and a receiver, a digital oscilloscope, and a personal computer with a custom-developed program installed. The program was developed on the LabVIEW 2012 platform and comprises two main components, a user interface and a block diagram. The user interface consists of three panels: a signal acquisition and selection panel, a display panel, and a calculation panel. The block diagram comprises four blocks: a signal acquisition block, a peak signal analysis block, an acoustic properties calculation and display block, and an additional block. Interestingly, the system can be operated in both online and offline modes. For the online mode, the measurements are performed by connecting the system with a Rigol DS2000 Series digital oscilloscope. In contrast, the measurements are carried out by processing the saved data on the computer for the offline mode. The accuracy and consistency of the developed system was validated by a KB-Aerotech Alpha Series transducer with 5 MHz center frequency and a Rigol DS2202 two-channel 200 MHz 2 GSa s-1 digital oscilloscope, based on the measurement of the acoustic properties of three poly(methyl methacrylate) samples immersed in a medium at a temperature of (24.0 ± 0.1) °C. The findings indicated that the accuracy and consistency of the developed system was exceptionally high, within a 1.04% margin of error compared to the reference values. As such, this computerized system can be efficiently used for the acoustic characterization of non-porous solid tissues, given its spontaneous display of results, user-friendly interface, and convenient hardware connection

Microrheological measurement of microcrystalline cellulose solution using single particle tracking

The aim of the research was to develop micro rheological measurement system to determine the alpha apparent and the complex shear modulus of microcrystalline cellulose (MCC) solutions based on a single particle tracking technique (SPT) using video microscopy (VM). The temporal displacement of a micro particle, acted as a probe in MCC solution was recorded, tracked and analyzed using custom-made MATLAB program. Videos were recorded at 30 fps resulted in the output of radial frequency range from 0.4 rad/s to 10 rad/s. The results from the local measurement in MCC solutions were compared with the bulk measurement using rheometer. The measurements were dependent on the local position of the probe in the solution. The results from the developed SPT-based measurement system were comparable to the common measurement using rheometer

Floral structure for textile-based metamaterial absorber

Based on an annulled circle structure metamaterial absorber (MMAb), a floral structure MMAb design is proposed for performance improvement especially on absorptivity. Since the initial purpose of designing the MMAb is for hiding one’s existence from electromagnetic motion detector, it is expected that the MMAb will has flexibility as one of its characteristics. The MMAb composes of textile-based substrate in between floral structure at the top and ground plane at the bottom, based on metallic plate. The targeted center frequency is 10.525 GHz and through series of simulation done in CST Microwave Software, the MMAb can reach up to 97.03% of absorptivity. The operating angle can be extended at least 68o before its absorptivity deteriorated below 80%. In addition, the proposed MMAb has a high absorptivity regardless of the polarization angle of the electromagnetic waves

Elastic constant determination of hardwoods using ultrasonic insertion technique

Ultrasonic insertion technique (IT) is an ultrasonic technique which involves sample immersion in a solution to determine its acoustic properties. IT is normally used to determine the acoustic properties of a medical phantom. We proposed the use of IT as an alternative technique to the common contact ultrasonic technique: through-transmission technique (TT) for determining the elastic constant of hardwoods in longitudinal, tangential and radial directions. The elastic constant of twelve rectangular-shaped Malaysian hardwoods from three different categories; heavy, medium and light with the density ranging from 602 to 992 kg m−3 were determined using IT and TT. Both techniques were carried out at 24.0 °C surrounding temperature and utilized 2.25 MHz ultrasonic transducers. Data from both techniques were compared to validate the use of the proposed technique. Findings indicated that IT offers consistent and accurate results for, tangential and radial elastic constants (TEC and REC) within 8.89% and 5.86% differences, respectively compared to TT for all tested hardwoods. IT offers an alternative technique for TEC and REC determinations of precious wood samples

Textile artificial magnetic conductor waveguide sheet with monopole antennas for body centric communication

A textile Artificial Magnetic Conductor (AMC) sheet-like waveguide made of fleece fabric with a wideband coplanar monopoles were designed. The AMC surface is designed to have in-phase reflection at 2.45GHz with the aim to improve the transmission between antennas. The S11 and S21 performances of two antennas with textile AMC sheet was investigated in a free space environment as well as near to human body setting. The effect of different antennas' orientations was also considered. Compared to free space environment, S21 transmission between two antennas was enhanced up to maximum -5.7dB when textile AMC waveguide sheet was placed beneath them. Significant transmission improvement has been observed for both off-body and on-body placements. The in-phase reflection characteristic of the AMC contributes to the transmission enhancement

New metamaterial structure with reconfigurable refractive index at 5G candidate band

A new metamaterial structure with a reconfigurable refractive index for beam tilting in future fifth-generation (5G) networks has been designed and numerically investigated. The novel structure operates at 28 GHz and consists of a stairway-shaped resonator (SSR) printed on the top view of the substrate layer. The inductance and capacitance (LC) equivalent circuit model is introduced to estimate the electromagnetic behavior of the SSR unit cell. The circuit model data agreed well with the full-wave computer simulation technology (CST) simulation. The proper configuration of the SSR unit cell offers a very low loss of -0.26 dB. To control the refractive index of the proposed structure, two active components, PIN diodes, are formed in the gaps of the structure. Consequently, the SSR can be switched between four states with different refractive index values, which are -60, -14, 0, and -12 (Nicolson Ross Weir (NRW) method) and -58, -12.5, 1, and -10.4 (Robust Retrieval Method (RRM)) at 28 GHz. The return loss, insertion loss, and real parts of the refractive index are studied and investigated at each reconfigurable state. The copper strip and the measured S-parameters of the proposed PIN diode are used in the simulation to achieve reconfigurability

Detection of the faulty sensors on basis of the pattern using symmetrical structure of linear array antenna

In this paper, a simple method is proposed to diagnose the position of the damaged sensors. The position of the damaged sensors is diagnosed on the basis of the null depth level and the number of nulls for the degraded radiation pattern. The method is initiated with tabulation of the array radiation pattern with a single damaged sensor. The corresponding pattern is set as the reference to the radiation pattern of the failed sensors. The tabulated damaged array sensors are compared to a configuration of the assumed damaged sensor. The radiation pattern with deeper null depth level will be the location of the damaged sensor. Moreover, the symmetrical sensor damaged (SSD) technique diagnose the position of damaged sensor, in which on the basis of nulls one can detect the location of damaged sensors. The proposed method diagnoses the location of damaged sensors on the basis of pattern without complex computation as compared to available methods

Flexible ultra-wideband antenna incorporated with metamaterial structures: multiple notches for chipless RFID application

A coplanar waveguide (CPW) ultra-wideband (UWB) antenna incorporated with metamaterial—split ring resonator structure—that operates from 3.0 to 12.0 GHz is proposed for chipless RFID tag. The 30 mm × 40 mm flexible chipless RFID tag is designed on the fleece substrate (εr = 1.35, thickness = 1 mm and tan δ = 0.025). A six-slotted modified complementary split ring resonator (MCSRR) is introduced into the ultra-wideband antenna to produce multiple band notches at 3.0, 4.0, 5.0, 6.0 and 7.0 GHz. The frequency shifting technique is introduced for designing a high-capacity chipless RFID tag with compact size. Each MCSRR is able to code in four different allocations (00, 01, 10 and 11). To achieve encoding of 10-bits data (10,234 number), six MCSRRs are proposed with three-slotted MCSRR in the radiator and three-slotted MCSRR in the ground plane

Forensic Building: Deterioration and Defect in Concrete Structures

Forensic building is needed to examine the affected building structure components to assess the structural integrity. This paper highlights some of the studies involved on affected concrete structures in various building types where the non-destructive test (NDT) and destructive tests. The structural integrity can be evaluated based on the extent of deterioration from the experimental results for instance the cause of the corrode reinforcements was due to inadequate concrete cover, whereas the failure of the concrete wall was due to structures’ under design which leads to the collapse of the wall. The condition of the floor slab that experience vibration was assessed from the Laser Doppler Vibrator test (LDV). Based on the test results the peak acceleration of the particular floor slab is higher