Frequency Points Research Articles

Design of a transmissive dual-frequency polarization rotator for linearly polarized electromagnetic wave

This paper presents the design of a transmission-type dual-frequency polarization rotator for linearly polarized electromagnetic wave. The rotator facilitates polarization conversion for incident waves at any azimuth angle ϕ at two specific frequency points, resulting in a transmission wave with a counterclockwise rotation of 2ϕ. The proposed polarization rotator structure comprises three metal layers separated by two dielectric substrates. It includes two large rectangular metal patches positioned orthogonally along the x- and y-axes, respectively, as well as two small rectangular metal patches also positioned orthogonally along the x- and y-axes, respectively. The upper and lower metal layers act as the receiving and radiation ends, respectively. The transmitting and receiving ends are interconnected through coaxial metal holes. Remarkably, polarization conversion efficiencies exceeding 0.95 and 0.94 at 12 and 17 GHz, respectively, are achieved, and these high conversion efficiencies remain consistent as the azimuth angle of incidence changes. Furthermore, experimental results obtained from fabricated samples align well with the simulation ones, thus validating the effectiveness of the proposed polarization rotator. The proposed transmissive dual-frequency polarization rotator exhibits good practical application prospects in mobile satellite communications, GNSS, WLAN, etc.

Ultrafast light-driven metasurfaces with an ultra-broadband frequency agile channel for sensing.

Active terahertz metasurface devices have been widely used in communication technology, optical computing and biosensing. However, numerous dynamically tunable metasurfaces are only operating at a single frequency point or in a narrow range, limiting the further possibility of the devices to meet contemporary broad-spectrum biosensing requirements. In this paper, a novel compact biosensor is proposed with an ultrawide resonance frequency agile channel shifted from 0.82 to 1.85 THz, with a tuning functionality up to 55.7%. In addition, under optical pumping irradiation, the modulator with ultra-fast response is able to complete the ultra-wideband resonant mode conversion from the Fano mode to the electromagnetically induced transparency (EIT) mode within 4 ps, and achieves a frequency shift sensitivity of 118 GHz RIU-1 and 247 GHz RIU-1 at 0.82 and 1.85 THz, respectively. This mechanism implements both refractive index and conductivity sensing functions, which provide a wealth of sensing information. Thus, this work presents the possibility of realising the detection of ultra-wide fingerprint spectra and can be extended to a wider range of optical fields.

Study on detection of intracerebral hemorrhage based on frequency difference of permittivity

Introduction: Current detection of intracerebral hemorrhage (ICH), whether employing Electrical Capacitance Tomography (ECT) or other electrical imaging techniques, rely on time-difference measurements. The time-difference methods necessitate baseline measurements from the patient in a non-hemorrhagic state, which is impractical to obtain, rendering rapid detection of ICH unfeasible.Methods: This study introduces a novel approach that capitalizes on the distinct dispersion characteristics of the permittivity in brain tissue and the spectral variance of the permittivity between blood and other brain components. Specifically, the frequency-dependent variations in the permittivity are employed to achieve absolute detection of ICH, thereby eliminating the need for non-hemorrhagic baseline data. The methodology entails identification of two frequency points that the frequency-dependent variation in the permittivity at these two frequency points manifest the maximal difference between blood and other brain tissues. Subsequently, this permittivity differential at the two identified frequency points is utilized for hemorrhage detection. Experimental measurements were conducted using an impedance analyzer and a parallel plate capacitor to capture the capacitance in four single-component substances—distilled water, sheep blood, isolated pig fat, and isolated pig brain—as well as three mixed blood compounds—distilled water enveloping sheep blood, pig fat encapsulating sheep blood, and pig brain surrounding sheep blood—across a frequency range of 10 kHz to 20 MHz.Results: The results show that in different frequency bands, it is indeed possible to distinguish single-component substances from mixed substances by the frequency difference of capacitance variation. Comparative analysis reveals that the 1 MHz to 5 MHz frequency range is most effective for detecting blood in distilled water. For blood detection in pig fat, a 10 kHz to 1 MHz frequency range is identified as optimal, while a 10 kHz to 0.5 MHz frequency range is advantageous for blood detection in pig brain tissue.Discussion: The findings confirm that absolute detection of ICH is achievable through frequency-dependent variations in the permittivity. However, this necessitates the identification of the frequency band manifesting the largest difference of frequency-dependent variation between single-component and mixed substances. The study acknowledges limitations primarily due to the use of anticoagulant-altered sheep blood, which exhibits permittivity divergent from those of natural blood. Additionally, the in vitro pig fat and pig brain samples, having been subjected to freeze-thaw cycles, also demonstrate permittivity unrepresentative of in vivo tissue.

Triple frequency bands terahertz metasurface sensor based on EIT and BIC effects

How to improve the sensitivity of terahertz wave metasurface biosensors has always been a research hotspot in the field of biosensors. In this article, we propose a well-shaped all dielectric metasurface, which can simultaneously excite electromagnetic induced transparency (EIT) and bound states in the continuum (BIC) effects, achieving high sensitivity sensing at three frequency points. The maximum Q value of refractive index sensing is 69238, with a sensitivity of 535 GHz/RIU and the figure of merits (FoM) of 85468. Moreover, the structure exhibits EIT group delay effect, with a maximum group delay of 5.57ps. The results indicate that the well-shaped all dielectric metasurface enhances the interaction between terahertz waves and matter, which can not only achieve multi frequency terahertz high sensitivity sensing, but also be used for the design of new slow light devices.

Blind single-channel lamb wave mode separation using independent component analysis on time-frequency signal representation

Guided waves are widely employed in non-destructive testing, but the presence of dispersion and multiple modes poses a challenge in detecting and separating the received signals, thereby affecting the performance of testing algorithms. Traditional methods for ultrasonic wave mode separation rely on time-frequency transforms, which often require extensive post-processing or the selection of specific frequency points for mode separation. In contrast, this paper introduces a blind separation method that utilizes independent component analysis to facilitate blind single-channel Lamb wave multimode separation. The proposed method demonstrates robust performance even under high noise power levels, while effectively localizing the source energy in the time-frequency domain. Numerical and experimental tests validate the effectiveness of the proposed method, showcasing its ability to successfully separate signals from instantaneous linear mixtures.

Outer isolated detached resonance curve and its implications of a two-stage nonlinear dynamic system

This paper presents an innovative study of a two-stage nonlinear dynamic system, providing insights into the occurrence of Large-Amplitude Long-Duration Vibration State (LALDVS) and outer isolated detached resonance curves (OIDRCs). The Lagrange equations and the incremental harmonic balance method (IHBM) are used to uncover the fundamental mechanism of OIDRCs and to discover two and three OIDRCs that have not been previously reported. Multiple OIDRCs could have significant practical implications in engineering, as they indicate the possibility of unpredictable and potentially hazardous vibrations under certain operating conditions. The existence of OIDRCs depends on the jump frequency point being a Neimark-Sacker bifurcation, and the resulting phase diagram provides vital insights into the stability and bifurcation behaviors of the system. This work also explores the effect of stiffness on the nonlinear response behavior of the system and identifies the range of stiffness values that lead to LALDVS. The correctness of the theoretical calculation results is validated by comparing them with vibration experiment and simulation calculations. These results have practical implications for engineering and energy harvesting research, including identifying potential hazards associated with vibration and designing systems that maximize energy harvesting efficiency. Overall, these findings are innovative and have significant implications for predicting potentially hazardous vibrations in engineering and the design of energy harvesting systems.

Tunable Epsilon‐and‐Mu‐Near‐Zero Metacomposites

AbstractEpsilon‐and‐mu‐near‐zero (EMNZ) metamaterials have garnered significant attention in near‐zero‐parameter metamaterial research for their exceptional ability to attain concurrent near‐zero permittivity and permeability. Nowadays achieving EMNZ properties through the use of metacomposites remains a novel endeavor. Presented here is an innovative approach of near‐zero‐parameter metacomposites, illustrating excellent and tunable EMNZ properties in the radio frequency regime. The self‐organization approach is applied to construct the conductive 3D network and the circuits, serving as the underlying framework for achieving EMNZ properties. Near‐zero permeability is effectively maintained while permittivity reaches epsilon‐near‐zero frequency regime. Efficient manipulation of electromagnetic parameters is initially realized via adjusting component content in metacomposites. Significantly, an excellent EMNZ property is observed as carbon content reaches 15 wt.% at 915 MHz. Through both numerical simulations and experimental testing, the PGC metacomposites have exhibited tunneling effects and directional emission characteristics, confirming their EMNZ properties. Besides, the Lego‐like adjustment facilitates the achievement of EMNZ property and advances the EMNZ frequency point to 700 MHz, expanding the EMNZ range. Furthermore, thanks to the remarkable excitation effect of photo‐induced adjustment, the metacomposite with low‐carbon content also achieves extraordinary EMNZ properties. This research offers promising self‐organized EMNZ metacomposites and lays the foundation for future endeavors in precisely adjusting near‐zero parameters.

A two-stage model updating method for the linear parts of structures with local nonlinearities

Finite element model updating provides an important supplement for finite element modelling. However, some studies have shown that if the tested structure involves local nonlinearities due to damages, material properties and large deformation et al., it is difficult to achieve an accurate modified model using conventional model updating methods that are based on the assumption of linear structures. To address this issue, a two-stage model updating method separating the effects of local nonlinearities is proposed in this paper. Firstly, the underlying linear frequency response function is obtained by using the conditioned reverse path method. Then, combined with the Sherman-Morrison-Woodbury formula and the model updating objective function established by the frequency response function similarity metric, then structural model updating and damage detection are carried out as the second stage. Three numerical examples are given to illustrate the effectiveness of the proposed method. This method can not only accurately identify the location and quantify the extent of structural damages, but also has the advantages of not based on sensitivity, not depending on the selection of frequency points, not repeatedly calling the initial model et al. The proposed method has high computational efficiency and avoids the numerical problems often encountered by conventional frequency response function-based model updating methods.

A 77 GHz Power Amplifier with 19.1 dBm Peak Output Power in 130 nm SiGe Process.

This article reports a two-stage differential structure power amplifier based on a 130 nm SiGe process operating at 77 GHz. By introducing a tunable capacitor for amplitude and phase balance at the center tap of the secondary coil of the traditional Marchand balun, the balun achieves amplitude imbalance less than 0.5 dB and phase imbalance less than 1 degree within the operating frequency range of 70-85 GHz, which enables the power amplifier to exhibit comparable output power over a wide operating frequency band. The power amplifier, based on a designed 3-bit digital analog convertor (DAC)-controlled base bias current source, exhibits small signal gain fluctuation of less than 5 dB and saturation output power fluctuation of less than 2 dB near the 80 GHz frequency point when the ambient temperature varies in the range of -40 °C to 125 °C. Benefiting from the aforementioned design, the tested single-path differential power amplifier exhibits a small signal gain exceeding 16 dB, a saturation output power exceeding 18 dBm, and a peak saturation output power of 19.1 dBm in the frequency band of 70-85 GHz.

Lattice-induced strong coupling and localized electric field enhancement in complementary diabolo metasurfaces

In this paper, lattice-induced strong coupling and localized electric field enhancement in terahertz (THz) regime are discussed in complementary diabolo metasurface (MS) that composed of a metallic sheet having periodically arranged opening diabolo resonators. By adjusting the lattice period of the MS along x or y axis, hybridization between the lattice mode and eigenmode of the MS leads to strong or ultrastrong coupling. The strong and ultrastrong coupling effect can be used to enhance electric field at two hybridized frequency points. The maximum enhancement are respectively 8855 and 7191 times of the incident field when ultrastrong coupling occurs, which are much larger than 7090 and 6561 times when strong coupling occurs. In addition, the maximum enhancement with ultrastrong coupling effect is 5.4 times comparing with the purely electric resonance of individual complementary diabolo structure. Based on coupled-mode theory (CMT) and coupled oscillator model, the resonant peak positions of two hybridized modes and the transmission spectra of the MS are analyzed. The analyzed results perfectly match with the simulated results, which proves the validity of our perspective. The results suggest that the proposed metamaterials could pave a new way for the electric field enhancement and developments of integrated photonic devices in THz regime.

Power Quality Disturbance Detection Based on Partitioning-Improved Empirical Wavelet Transform

Power quality is an important indicator to measure the quality of power supply in power grids. With the large evasion accession of new energy sources, its randomness and volatility cause frequent transient power quality problems in power grids. With the large evasion accession of new energy sources, its randomness and volatility cause frequent transient power quality problems in power grids. Aiming at the detection of transient power quality disturbance, this paper proposes the empirical wavelet algorithm which improves the adaptive division. This paper improves the spectrum processing, frequency point selection and frequency band division to improve the adaptive division ability of the algorithm under complex perturbation signals. Combined with the Hilbert transform, a perturbation detection algorithm is proposed based on an improved empirical wavelet algorithm to extract the transient characteristics of the perturbation signal. Through software simulation, this method has good adaptive ability in the face of composite power mass transient disturbance and can accurately extract the transient characteristics of the signal.

Intelligent processing of electromagnetic data using detrended and identification

The application of the electromagnetic method has accelerated due to the demand for the development of mineral resource, however the strong electromagnetic interference seriously lowers the data quality, resolution and detect effect. To suppress the electromagnetic interference, this paper proposes an intelligent processing method based on detrended and identification, and applies for wide field electromagnetic method (WFEM) data. First, we combined the improved intrinsic time scale decomposition and detrended fluctuation analysis algorithm for removing the trend noise. Then, we extracted the time domain characteristics of the WFEM data after removing the trend noise. Next, the arithmetic optimization algorithm was utilized to search for the optimal smoothing factor of the probabilistic neural network (PNN) algorithm, which realized to intelligently identify the noise data and WFEM effective data. Finally, the Fourier transform was performed to extract the spectrum amplitude of the effective frequency points from the reconstructed WFEM data, and the electric field curve was obtained. In these studies and applications, the fuzzy c-mean and PNN algorithm are contrasted. The proposed method indicated that the trend noise can be adaptively extracted and eliminated, the abnormal waveform or noise interference can be intelligently identified, the reconstructed WFEM data can effectively recover the pseudo-random signal waveform, and the shape of electric field curves were more stable. Simulation experiments and measured applications has verified that the proposed method can provide technical support for deep underground exploration.

Echo Frequency Estimation Technology for Passive Surface Acoustic Wave Resonant Sensors Based on a Genetic Algorithm

Passive wireless surface acoustic wave (SAW) resonant sensors are widely used in measuring pressure, temperature, and torque, typically detecting sensing parameters by measuring the echo signal frequency of SAW resonators. Therefore, the accuracy of echo signal frequency estimation directly affects the performance index of the sensor. Due to the exponential attenuation trend of the echo signal, the duration is generally approximately 10 μs, with conventional frequency domain analysis methods limited by the sampling frequency and data points. Thus, the resolution of frequency estimation is limited. Here, signal time-domain fitting combined with a genetic algorithm is used to estimate SAW echo signal frequency. To address the problem of slow estimation speed and poor timeliness caused by a conventional genetic algorithm, which needs to simultaneously estimate multiple parameters, such as signal amplitude, phase, frequency, and envelope, the Hilbert transform is proposed to remove the signal envelope and estimate its amplitude, and the fast Fourier transform subsection method is used to analyze the initial phase of the signal. The genetic algorithm is thereby optimized to realize the frequency estimation of SAW echo signals under a single parameter. The developed digital signal processing frequency detection system was monitored in real time to estimate the frequency of an SAW echo signal lasting 10 μs and found to have only 100 sampling points. The proposed method has a frequency estimation error within 3 kHz and a frequency estimation time of less than 1 s, which is eight times faster than the conventional genetic algorithm.

Low-temperature relaxation of various samarium phosphate glasses

Abstract Glasses constructed, (1 − x) (0.6595P2O5–0.0958ZnO–0.2447PbO) · xSm2O3 with x = 0.00, 0.0045, 0.0089, 0.0132, and 0.0261 mol%, had been created to investigate the attenuation of longitudinal ultrasonic waves at 2, 4, 6, and 14 MHz frequencies between 120 and 300 K. At a variety of temperatures, clear peaks of a large absorption curve have been seen. These peaks are dependent on the structure of the glass as well as the switching frequency. Maximum peaks have been shown to shift to higher temperatures, and the increase in overall frequency points to the presence of some kind of relaxation process. A thermally induced relaxation process is responsible for producing a calm approach, which has been identified as a result of this mechanism. A quiet approach has been defined as a consequence of a thermally triggered relaxation mechanism. The variance of the mean energy of activation of the mechanism counts on primarily the amount of Sm2O3 mol%. Such dependency has been evaluated based on the loss of normal linear solid form, attaining low dispersion, and a large allocation of Arrhenius kind relaxation through temperature-autonomous relaxation power. The measured acoustical energy of activation values have been quantifiably represented based on the number of loss centers (amount of oxygen atoms that now move at a double-well potential).

OGC P17 Reporting nutritional outcomes following gastrectomy: A systematic mapping review

Abstract Background Following an international consensus agreement of patients and healthcare professionals (GASTROS Study), ‘nutritional outcomes’ have been identified as critically important to report in surgical trials for gastric cancer. A previous review has demonstrated that nutritional outcomes are rarely reported by trials, and little is known about how best to measure them. In preparation for future work on establishing an optimum approach to report and measure nutritional outcomes, a mapping review was undertaken to examine current approaches used by researchers in this field. Methods We conducted a systematic literature search (using MEDLINE, Embase, CINAHL, Cochrane and PsychInfo) and included randomised control trials and prospective studies reporting any form of nutritional outcome in patients following gastrectomy, between 2012 and 2022. The review was conducted using PRISMA guidelines and registered on the PROSPERO database (CRD42022365652). Full text reviews and data extraction were completed independently by three reviewers. Datapoints of interest included general trial and surgery characteristics, study types, duration and frequency of nutritional outcomes and the utility of nutritional screening measurement tools. Data collection and analysis was conducted on Microsoft Excel. Results 3288 abstracts were screened, yielding 87 studies (17220 patients) eligible for inclusion. 90% of trials were based in East Asia. 24% of trials reported biochemical, anthropometric, and weight-based outcomes. 21 different biochemical tests were reported by 74% trials, the most common marker being ‘albumin’. Anthropometric measurements were heterogenous with BMI and skeletal muscle index being the most frequently reported. 66% of studies reported patient weight as an outcome. 28% studies reported both nutritional screening and assessment. 48% of trials utilised screening tools. The frequency and time points at which nutritional outcomes were measured varied greatly. Conclusions This mapping review highlights significant variation in the reporting of nutritional outcomes. Consensus agreement is required to establish the optimum approach to use in trials and clinical practice.

Wideband hybrid metamaterial absorber via compound design of multiple mechanisms

Broadband and high efficiency are the two core indexes of absorption research, which usually requires a balance between them. Therefore, how to take into account both and achieve broadband and efficient absorption is a hot topic in current research. In this paper, by the compound design of multiple mechanisms, a kind of wideband hybrid metamaterial absorber (HMA) is proposed. The overall structure consists of a layer of patterned resistive film and a layer of magnetic absorbing material (MAM) separated by the air. The resistive layer is designed as square ring type to regulate the local magnetic field, which results in significant magnetic field enhancement within the MAM layer, and this mechanism provides a prerequisite for wideband and high-efficiency absorption in the low frequency band. Furthermore, due to the electrical losses of the resistive film, another absorption band is additionally excited in the high frequency band. Thanks to the multiple mechanisms, the absorption efficiency above 90% in the 3.2–22.0 GHz frequency band can be realized, and the thickness of the overall structure is 7.0 mm that is 0.07 of the wavelengths at the lowest frequency point. To demonstrate this method, a prototype is designed, fabricated and measured. Both the simulation and experiment results verify the effectiveness of the proposed method. This work provides a new method to design wideband and high-efficiency electromagnetic absorption structures and may find potential applications in multi-functional planar or conformal structures.

ANALISIS PREFERENSI KONSUMEN TERHADAP GULA SEMUT AREN DI PULAU LOMBOK

This study aims to: (1) Describe consumer buying behavior towards Crystals Palm Sugar from point of purchase, purchase frequency, purchase amount and purchase purposes on Lombok Island, (2) Analyze consumer preferences on Crystals Palm Sugar attributes on Lombok Island.
 The method used is the descriptive method. The unit of analysis in this study was the consumers of crystals palm sugar on the island of Lombok. Determination of the sample area using purposive sampling with the consideration that West Lombok Regency is an crystals palm sugar production location and sale location and the city of Mataram is a crystals palm sugar production retail outlet. The number of respondents in this study was 50 respondents that were determined by the accidental sampling technique. The types of data used are qualitative data and quantitative data. The data sources used are primary data and secondary data. The data analysis used was an interval scale evaluation and it was processed by conjoint analysis with the help of the SPSS version 25 application.
 The results of this study indicate that: (1) The purchasing behavior of crystals palm sugar consumers in Lombok Island is that they prefer to buy at the production site, twice a month, the number of purchases is > 1000 gr in a month, and the purpose of the purchase is for consumption. (2) Crystals palm sugar attributes that are consumer preferences based on utility value are original flavor 0.095, IDR15,000-IDR25,000 price 0.357, permanent bag packaging type 0.180, BPOM label 0.590, halal label 0.855, and 1000gr size 0 .332. The crystals palm sugyar attributes that respondents considered the most when choosing crystal palm sugar on Lombok Island in sequence, starting from most considered to least considered, were halal label value 23,599, price 21,068, BPOM label value 17,002, packaging type value 16,511, size value 14,601, and last one is the aroma attribute with an importance value of 7.219.

Low-RCS low-profile MIMO antenna and array antenna using a polarization conversion metasurface.

A specially designed dumbbell type polarization conversion metasurface (PCM) is proposed. The designed PCM achieves line-to-line polarization conversion in ultra-wideband (UWB) from 7.63 GHz to 18.80 GHz. A low-profile metasurface antenna composed of PCM and slot feed is proposed based on characteristic mode analysis (CMA), which realizes the integrated design of radiation and scattering. Because of the checkerboard scattering properties, low-radar cross section (RCS) low-profile multiple-input-multiple-output (MIMO) antenna and array antenna are designed with PCM. The low-RCS high-isolation low-profile MIMO antenna with size of 1.27×1.27×0.07λ 0 3 (λ0: the free-space wavelength corresponding to the center frequency point) operating at 5.8 GHz consists of four orthogonal arranged metasurface antennas. The isolation is greater than 26 dB with impedance bandwidth from 5.51 GHz to 6.06 GHz. In addition, the low-RCS high-gain low-profile array antenna with size of 2.55×2.55×0.07λ 0 3 is also designed. The operating band covers from 5.63 GHz to 6.12 GHz with the gain of 12-15.6 dBi. The RCS reduction of the two antennas for normal incidence is between 6 dB and 23 dB in both X- and Ku-bands. The measured results of the antennas agree with the simulated results, which shows that they have potential application value in 5.8 GHz WLAN wireless communication.

Metamaterial microwave sensor with ultrahigh Q-factor based on narrow-band absorption

A novel metamaterial sensor with ultrahigh Q-factor of 665.85 and 1883.3 at 5.46 GHz and 11.3 GHz is presented in this paper, which consists of a metal pattern with cross structure and ring (CSR), a dielectric slab FR4 and a metal backplate. Based on the principle of the absorber, the Q-factor of the two resonance frequency points is improved by optimizing the ring and cross structure to strengthen the resonance. It is because of its wide angle incidence, insensitive polarization, and narrow-band absorptivity greater than 90 %, which is very conducive to the design of material refractive index sensor. Equivalent circuit method is used to analyze the characteristic of the metamaterial structure and the experimental results are in good agreement with the simulations. By loading three giving materials, the sensing function is analyzed and verified in experiments. The design has the advantages of ultrahigh Q-factor, angle and polarization insensitivity, and has potential application prospects in metamaterial sensing.

2D acoustofluidic distributions in micro-chambers modulated by Sierpiński-type structural plates

In this study, a series of Sierpiński-type structural plates have been artificially introduced to generate diversified acoustofluidic distributions in the originally-static microfluidic chambers, which are stimulated under the oscillation of incident acoustic waves at different input frequency points. The complicated interactions between quasi/pseudo-Sierpiński-carpet shaped structural plates and incident ultrasonic waves, including acoustic reflection and diffraction, can initiate sophisticated spatio-temporal discrepancies along the sound propagation path and induce heterogeneous acoustic streaming vortices. In comparison with the existing construction strategies of microfluidic lab-on-a-chip devices, the introduction of fractalized elements like quasi/pseudo-Sierpiński-carpet shaped structural components can provide remarkable insights and expand application scenarios of unconventional acoustofluidic approaches, which is conducive to driving ultrasonic micro/nano manipulation technology from monotonousness to diversification. The preliminary research demonstrates the feasibility of considering Sierpiński-type structural features as tunable ingredients to customize acoustofluidic apparatuses for the exploration of topographical manipulation of micro/nano-scale particles and orientational operation of biological specimens.