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Purpose This study aims to leverage inertial sensors via a walk test to associate kinematic variables with functional assessment results among walkable subjects with chronic stroke. Design/methodology/approach Adults with first-ever stroke survivors were recruited for this study. First, functional assessments were obtained by using Fugl–Meyer Assessment for lower extremity and Berg balance scales. A self-assembled inertial measurement system obtained walking variables from a walk test after being deployed on subjects’ affected limbs and lower back. The average walking speeds, average range of motion in the affected limbs and a new gait symmetry index were computed and correlated with the two functional assessment scales using Spearman’s rank correlation test. Findings The average walking speeds were moderately correlated with both Fugl–Meyer assessment scales (γ = 0.62, p < 0.01, n = 23) and Berg balance scales (γ = 0.68, p < 0.01, n = 23). After being modified by the subjects’ height, the new gait symmetry index revealed moderate negative correlations with the Fugl–Meyer assessment scales (γ = −0.51, p < 0.05) and Berg balance scales (γ = −0.52, p < 0.05). The other kinematics failed to correlate well with the functional scales. Practical implications Neuromotor and functional assessment results from inertial sensors can facilitate their application in telemonitoring and telerehabilitation. Originality/value The average walking speeds and modified gait symmetry index are valuable parameters for inertial sensors in clinical research to deduce neuromotor and functional assessment results. In addition, the lower back is the optimal location for the inertial sensors.

The fabrication of Fresnel focusing lenses operating at frequencies of 100 and 200 MHz was investigated in order to enhance the focusing efficiency of ultrasonic energy. The effects of process parameters on the four-level Fresnel lens profiles were discussed to find a most feasible fabrication procedure through these experiments. The quality of Fresnel lenses was improved when two-and three-mask processes using SiO2 film as the hard mask were employed. Besides, a better side-wall profile of Fresnel lens was obtained by using the three-mask process as compared to the two-mask one.

Breast cancer remains the most frequently diagnosed cancer and is the leading cause of neoplastic disease burden for females worldwide, suggesting that effective therapeutic and/or diagnostic strategies are still urgently needed. In this study, a type of indocyanine green (ICG) and camptothecin (CPT) co-loaded perfluorocarbon double-layer nanocomposite named ICPNC was developed for detection and photochemotherapy of breast cancer. The ICPNCs were designed to be surface modifiable for on-demand cell targeting and can serve as contrast agents for fluorescence diffuse optical tomography (FDOT). Upon near infrared (NIR) irradiation, the ICPNCs can generate a significantly increased production of singlet oxygen compared to free ICG, and offer a comparable cytotoxicity with reduced chemo-drug dosage. Based on the results of animal study, we further demonstrated that the ICPNCs ([ICG]/[CPT] = 40-/7.5-μM) in association with 1-min NIR irradiation (808 nm, 6 W/cm2) can provide an exceptional anticancer effect to the MDA-MB-231 tumor-bearing mice whereby the tumor size was significantly reduced by 80% with neither organ damage nor systemic toxicity after a 21-day treatment. Given a number of aforementioned merits, we anticipate that the developed ICPNC is a versatile theranostic nanoagent which is highly promising to be used in the clinic.

To assess cutting-tools degradation, mounted accelerometers and current clamp probes were used to acquire machining vibration for both the band-saw machine and the drilling machine, of which a structural-steel machining center is composed. Significant features were first extracted through spectral analysis, and tool degradation assessment was conducted through using a supervised learning scheme, self-organizing map. The results reveal that 10% remaining useful life can be predicted before the band-saws and drills wore out.

In this paper, signal analysis techniques based on Teager-Kaiser energy operation and envelope spectra for fault detection of the discharge valve of a reciprocating compressor is proposed. The method can accurately identify the existing fault of vibration signal features that it simulated by the synthetic signals. A two-phase study was designed to explore the signals simulation and the experimental validation. Signals simulation, which is based on the operation of a reciprocating compressor, and experiment design, which uses three conditions. The first stage is to simulate the operation of the reciprocating compressor, which is to simulate a synthetic signal for the cycle and impact. The synthetic signal is composed of a noise, square wave, and pulse wave. In this study, the synthetic signal is signal-processed by the Teager-Kaiser energy operator and the envelope spectrum that they can effectively extract feature signal and the noise almost is eliminated. The second stage is applied to the signal processing technique proposed in the first stage. Experimental verification of experiment design by the different operating conditions of reciprocating compressor valves. Through the above analysis technology, it is proved that the synthetic signal can be eliminated the background noise to obtain the feature signal. The feasibility of the proposed approach is verified by simulation results, the experiment is to validate with the measurement signals from a six-cylinder reciprocating compressor under different valve conditions. Simulations and experimental results support the proposed technology positively.

This study presents a novel measurement scheme for near-infrared diffuse optical tomography through employing square-wave driving light sources to simultaneously obtain amplitude and phase delay data of multiple sinusoids for the reconstruction of optical-coefficient images.

In this study, we proposed and implemented a ring-scanning mechanism in the prone position for application in breast tumour detection. The current scanning module using two zones with three light sources in each zone enables the acquisition of 36 source and 30 detection data (36S × 30D) items during the optical information collection phase. This study employed only three photomultiplier tubes (PMTs), instead of 30 PMTs used in a fixed model. In particular, the circular scanning of source-and-detection module actually behaves as more channels and can acquire more optoelectrical data as the scanning module operates in a fractional motion of a single channel-to-channel span. In this study, the optoelectrical measurement system was first calibrated; then, the feasibility of optical-coefficient image reconstruction was verified using several heterogeneous cylindrical phantoms. The reconstructed μ a and μ s ′ images through multilayer scanning presented good outcomes, implying that the developed system is promising for 3D scanning of breasts. In a quantitative analysis, the contrast-to-noise ratios of the μ a and μ s ′ images (6.00 and 4.97, respectively) for the flexible scanning scheme were superior to those derived for the fixed scheme (5.05 and 4.31, respectively). This indicates that the higher amount of detection information obtained through the proposed scanning module can enhance the spatial resolution of the reconstructed images while retaining an acceptable scanning time.

Osseointegration is the key to the success of surgery of dental implantation. In this study, we proposed, implemented and explored a handheld and noncontact electromagnetic-type stability assessment device for the use after surgery. The device with two pairs of dual inductors incorporating with a driving signal of swept wavelets was first proposed. This detection device feeds 200–10 kHz of alternating current into an inductor to produce swept broadband magnetic flux and excite the implant structure with a magnetic pole. The implant vibration causes magnetic-flux changes and generates an induced electromotive force. The implant structure resonance frequency (RF) can be characterized to exhibit osseointegration status by evaluating the frequency response function. In vitro bone block experiment and in vivo animal testing were performed to validate the developed device. For bone block experiment on fourteen designs, besides two cancellous bones and two cortical-shell thicknesses, four interface tissues produced using varied mixing ratios of epoxy adhesive were to imitate osseointegration progress. Further, a pilot animal test was conducted on five female New Zealand rabbits to assess implant osseointegration in live bodies. Statistical analyses for varied bone models on measured RF, and the regression analysis between the measured RF and OsstellTM ISQ for in vivo testing were performed. The correlation analysis on the built regression models shows a close relationship between the measured RFs and ISQ quotients with the determination coefficients up to over 0.9.

High focusing efficiency of a multi-level Fresnel lens is desired when it is designed and fabricated. How to estimate the focusing efficiency is an important issue after the Fresnel lens is made. W...

Diffuse optical imaging enables to reconstruct distribution of optical properties, absorption and scattering coefficients, in tissue for breast cancer detection based on diffusion equation with the help of the initial guess obtained from measured data. To estimate the initial guess of the optical-property coefficients, an analytical solution of diffusion equation can be used and compared with the measured data. The analytical solution for a homogeneous infinite medium can be obtained in the frequency domain, expressing that the photon intensity and the phase lag relative to the distance between source and detector in a linear relationship. In this study, a succinct calculation using the trigonometric relation is proposed to estimate the optical-property coefficients. A tank-type and a cylinder Lipovenoes phantoms with two concentrations of 1.25% and 2.5% are employed and measured for verification. It is found that the method proposed here shows better results and results in estimation errors of 0–14.81% for μa and 20–42% for μs′.

When a rotary machine is running, from which the acquired vibro-acoustic signals enable to reveal its operation status and health condition. The study proposed a DSP-based adaptive angular-velocity Vold-Kalman filtering order tracking (AV2KF_OT) algorithm with an online real-time nature for signal interpretation and machine condition monitoring. Theoretical derivation and numerical implementation of computation schemes are briefly introduced. An online real-time monitoring system based on the AV2KF_OT algorithm, which was implemented through both a digital signal processor and a user interface coded by using LabVIEW, was developed. Two experimental tasks were applied to justify the proposed technique, including (i) the detection of startup on the fluid-induced whirl performed through a journal-bearing rotor rig, and (ii) the separation of close orders from the measured signals of a multifunction transmission-element ball-bearing bench.

On the basis of resonance frequency analysis, a noncontact handheld assessment device that employs the vibro-acoustic technique with acoustic excitation and displacement response sensing was developed to quantify the stability of dental implants. The assessment technique employed in the developed device is superior to the magnetic sensing technique that uses an accessory for assessment. The calculated response spectra that characterized dental-structure resonance indicated the trend of osseointegration. In vitro and in vivo tests were performed to verify the performance of the developed device. For in vitro bone block testing, in addition to two cancellous bones and two thicknesses of cortical shells, interface tissues produced using different mixing ratios of resin to hardener epoxy adhesive were used to mimic the osseointegration progress. Furthermore, preliminary animal testing was conducted on rabbits to observe implant osseointegration in live bodies. Statistical analyses for varied designed bone models on measured resonance frequency, and the regression analysis between VA and Osstell™ ISQ for in vivo testing were performed. The necessary statistical analyses on various issues were considered as well as their descriptions. The developed noncontact vibro-acoustic assessment device can be used to monitor the implant stability status without having to use a mounted accessory.

The use of inertial measurement units associated with various algorithms has been proposed and developed to evaluate functional abilities and kinematics for stroke patients. In previous research, complex mathematical models were adopted successfully to clarify and to validate the functional results from different sensors. However, only a few algorithms stemmed from the process of motor recovery after a stroke or the way to administer clinical assessment scales. Based on the recovery process or how to conduct the assessment scales, the algorithmsensor based module is supposed to accurately classify clinical motor recovery status and to provide additional kinematics in stroke survivors. In this study, only one sensor is affixed on the dorsum of the affected foot to reduce the burden on a weak extremity. A special movement while in seated, extend their knee and then dorsiflex their feet, based on the motor recovery process after stroke is proposed and tested to classify Brunnstrom stages for lower extremities. After analyzing 24 participants and adopting suitable threshold values for different Brunnstrom stages, the overall accuracy is 86.8%. The ability to distinguish Brunnstrom stage II from others can even reach a 100% accuracy. The accuracies for distinguishing Brunnstrom stage III, stage IV, and stage V are 86.6%, 94 %, and 92.8%, respectively. We also analyze these misclassified data and investigate why the errors occurred. The results reveal the feasibility of the kinematics-based algorithm even using a single sensor.

A working prototype of an optical breast imaging system involving a dual-direction parallel-plate scanning scheme in combination with a mammography machine was demonstrated and applied in imaging healthy and malignant breasts in a clinical environment.

The phenomenon of fluid-induced instability existing in fluid-film bearing systems has been coped with for long time. The study aims to soothe and even eliminate the occurrence of whirl in rotary machinery by increasing the threshold of instability through the anti-swirl injection using the linear quadratic regulator based optimal control. An acceptance region was established in order to decide starting up the control process. Three case studies were carried out to illustrate the effectiveness of the control scheme. The research results demonstrate that the control scheme incorporating with the acceptance region enables to avoid the occurrence of fluid induced instability in rotary machinery. Moreover, the developed techniques can also be applied in other fluid-induced instability problems such as whip and rub, etc.

We implemented a ring-scanning mechanism in a prostrate type for breast tumor detection. Reconstructed μa and μs′ images of multi-layers scanning are presented in good outcomes, showing it’s promising for the 3D scanning of breast.

Mechanical systems under periodic loading due to rotary operation usually respond in measurements with a superposition of sinusoids whose frequencies were integer or fractional integer multiples of the reference shaft speed. When the rotary machines are running, acousto-mechanical signals acquired from the machines enable to reveal their operation status and machine conditions. The study proposed a DSP-based adaptive angular-velocity Vold-Kalman filtering order tracking (AV2KF_OT) algorithm with online real-time nature for signal interpretation and machine condition monitoring. Theoretical derivation and numerical implementation of the computation scheme was briefly introduced. An online real-time condition monitoring system based on the AV2KF_OT algorithm, which was implemented through both a digital signal processor (DSP) and a man-machine interface coded by using LabVIEW®, was developed. An experimental task, the startup detection on the fluid-induced whirl performed through a journal-bearing rotor rig, was used to justify the proposed technique.

This study is to develop an automatic classification system for lower limb Brunnstrom stage of hemiparetic patients. The measurement system is employed both IMU and sEMG to acquire the lower limb motion signals from patients. Afterward, this study extracted some useful features for the proposed rule-based classification system and compared different classification algorithms such as k-nearest neighbor, artificial neural network and support vector machine. Instead of leave one out cross validation, the leave subjects out cross validation was used to calculate the successful rate of classification. The results of the experiment on seventeen men and seven women at mean age: 60.6 ± 12.4 years after stroke for more than 6 months show that SVM (95.2%) has the highest accuracy to classify Brunnstrom stage than k-NN (89.2%) and ANN (92.3%). The robustness of this classification system was verified by training different number of subject data. According to the classification result, it can be concluded that the proposed classification system has the potential to predict the lower limb Brunnstrom stage for hemiparetic patients.

The purpose of this study is to propose an objective contrast-and-size detail (CSD) analysis for near infrared diffuse optical tomography (NIR DOT), of which the concept is derived from the subjective contrast detail (CD) analysis. We define a measure for numerical CSD analysis based on the resolution estimation of contrast and size. Following that, the contrast-and-size map of resolution can be calculated and displayed for each corresponding image in the map; furthermore, a CSD resolution curve can be plotted by calculating the average value of the projection corresponding to the physical quantity/axis (size or contrast). To provide some worked examples about the proposed CSD analysis evaluating the imaging performance of different reconstruction methods, Tikhonov regularization and edge-preserving regularization with different weighting functions were employed. Results suggested that using edge-preserving regularization with the generalized Lorentzian weighting function is the most attractive for the estimation of absorption-coefficient images.

Breast tissues like fatty and fibroglandular ones are adipose mainly and possess high scattering nature, so that they diffuse and make the light approximately uniformly distribute over the measured cross-section besides absorbing to reduce the light intensity. Strong cause-and-effect relationships exist between absorption and intensity decay, and between scattering and phase delay as well. Thereby in a diffuse optical imaging system it is a general practice to estimate absorption coefficients from the measured intensity since it reflects most of the absorption property. This study aims to illustrate that both μ a and μ ′ images of breast can be reconstructed by only direct-current data reliably to a certain extent. Varied sets of phantom design with assigned absorption/scattering properties for inclusion and background were synthesized and image reconstructed to demonstrate this perspective. Moreover, we employed a slab-type diffuse optical imaging system with a dual-direction direct-current NIR measurement module, where reconstructed images were compared between with and without reflectance NIR data.

Diffuse optical imaging (DOI) is emerging as a new functional imaging modality that can be used for breast cancer screening. Due to the ill-posed inverse problem for DOI image reconstruction, regularization is essential to remedy such a drawback. In our previous study, we have successfully implemented edge-preserving regularization into image reconstruction algorithm for improving the reconstructed images. In this study, we incorporate additional anatomical image, which can be obtained from other imaging modality such as mammography or magnetic resonance imaging, although showing no tumor information, into edge-preserving regularization for further improving the reconstructed images. Reconstruction results show that the quality of reconstructed images can be significantly improved.

Traditional envelope analysis must examine all the resonant frequency bands during the process of bearing fault detection. To eliminate the above deficiency, this paper presents an insight concept based on the empirical mode decomposition to choose an appropriate resonant frequency band for characterizing feature frequencies of bearing faults by using the envelope analysis subsequently. By the band-pass filtering nature of the empirical mode decomposition, the resonant frequency bands are allocated in a specific intrinsic mode function. The inner or outer ring of bearings scratched intentionally is used to validate the feasibility of the proposed idea, and comparisons with the traditional envelope analysis are addressed. The experimental results show that the proposed insight concept can efficiently and correctly diagnose the bearing fault types.

A two-mask fabrication process of a four-level Fresnel lens was used to evaluate its characteristics through investigating the effect of SU-8 photoresist on the profile of the focusing lens. A two-step deposition of ZnO films was applied to develop a feasible fabrication of a piezoelectric transducer with the structure Al/ZnO/Pt/Ti/SiO2/Si under reasonable conditions, which include deposition pressure of 0.7 Pa and 1.3 Pa, RF power of 100 W and 178 W, and sputtering gas ratio Ar:O2 = 1:3 and 1:1 for first and second step deposition, respectively. Highly c-axis textured ZnO films were successfully obtained through two-step deposition process.

Oil whip induces self-excited vibration in fluid-handling machines and causes self-excited reverse precessional full annular rub, known as “dry whip”, which is a secondary phenomenon resulting from a primary cause, that is, “coexistence of oil whip and dry whip”. For predicting these instabilities, the clues are hidden in start-up vibration signals of these kinds of machines. This paper presents a method for predicting these kinds of instabilities. First, a Hilbert spectrum combining a full spectrum, which is named the “full Hilbert spectrum”, is developed to reveal the whole process. Next, the transient position of a shaft centerline combining an acceptance region is introduced to predict instability at an early stage. The results presented in this study amply demonstrate the transition from stability to instability and the behavior of fluid-induced instability and rub in rotor systems. By this finding, bearing designers can completely understand these instability phenomena existing in fluid-handling machines. As a result, the control parameter for designing controllable bearings can be obtained and the instability problems can be resolved. Consequently, these findings are worth noting.

The influence of fabrication parameters on ZnO film properties has been analyzed through conducting several experiment processes to develop an appropriate deposition condition for obtaining highly c-axis textured films. A transducer with the structure of Al/ZnO/Al/Si was fabricated at low deposition rate and under a temperature of 380 °C in a mixture of gases Ar:O2 = 1:3, and RF power of 178 W. Pt/Ti was employed as the bottom electrode of the transducer fabricated in a suitable substrate temperature, which starts increasing at 380 °C with an increment of 20 °C for each 2 h stage of the deposition. Highly c-axis textured ZnO films have been successfully deposited on Pt/Ti/SiO2/Si substrate under feasible conditions, including RF power of 178 W, substrate temperature of 380 °C, deposition pressure of 1.3 Pa and Ar:O2 gas flow ratio of 50%. These conditions have been proposed and confirmed through investigating the influences of the sputtering parameters, such as substrate temperature, RF power and Ar:O2 gas flow ratio, on the properties of ZnO films.

The elimination of whip using electromagnetic exciters (EEs) is investigated in this paper. First, mathematical models of a rotor-bearing system are derived. The threshold of instability determining if the rotor-bearing system experiences fluid-induced instability is obtained. Then, an experimental rotor-bearing system is designed and constructed to justify the elimination of whip, and orbit, spectrum, and spectrum cascade plots are obtained from the experimental data. The proposed procedure applies root locus plots to simulate the threshold of instability, and the spring model is used to compute the stiffness that the system needs to address the whip problem. Moreover, design examples are illustrated to explain the calculation process that tackles the proportional (simulating stiffness) and derivative (simulating damping) parameters of the EE to improve the stiffnesses of the rotor-bearing system. The main contribution of the present experimental work is that by using the EE it is possible to increase the stiffness of the rotor-bearing system and lead to the rotor-bearing system with a higher threshold of stability and eliminate the whip instability.

Self-excited reverse precessional full annular rub, known as “dry whip”, is a secondary phenomenon resulting from a primary cause and may lead to a machine catastrophic failure; i.e., “coexistence of oil and dry whips” which occurs repeatedly with constant frequency and amplitude in small clearance cases. This paper presents a technique using an electromagnetic actuator, which can raise the threshold of instability of fluid-film bearings and then eliminate both oil and dry whips in the normal, operational range. The study constructs a set of experimental setup, sets up a general model of a rotor-bearing-seal system with an electromagnetic actuator to derive the corresponding governing motion equations, evaluates the supplemental stiffness supplied by the electromagnetic actuator, judges instabilities by root locus plots, and finally establishes a set of criterion for eliminating coexistence of oil and dry whips. Experimental results demonstrate that the coexistence of the oil and dry whips of the rotating machine can be removed effectively. The proposed technique can be used to diagnose rub and fluid-induced instability in this kind of rotating machine.

This paper describes an experimental investigation of whirl elimination of a hydrodynamic bearing with an electromagnetic exciter (EE) and includes a stability analysis through a root locus plot. The test apparatus incorporates the EE, which provides additional stiffness through a PD algorithm in order to stiffen a rotating machine to resolve fluid-induced instability. The stiffness of the hydrodynamic bearing gives a significant contribution to the occurrence of unstable vibrations as the speed or the load of a rotating machine increases. With regard to the whirl-eliminated investigations, the EE used to raise the stiffness of the rotating machine can cause important changes in the stability of the rotating machine. The threshold of stability derived in this paper that affects stability conditions can be used to define the stability margin of the rotating machine. A simple control scheme is used to calculate the amount of the supplemental stiffness supplied by the EE, and is confirmed through experiments. To offer a faster, more stable and more effective strategy for whirl elimination, the dynamic behavior of a rotor system affected by fluid-induced whirl instability phenomena has been successfully studied.

The paper presents the implementation and application of an adaptive hybrid controller for the servo system of a DVD drive in recreation vehicle, to suppress tracking disturbance with frequencies less than 100 Hz caused by environmental vibration and to improve the performance of tracking servo system. The adaptive hybrid servo control (AHSC) technique consists of both the active feedforward and feedback disturbance cancellation. In this paper, the controller is designed based on an adaptive digital filter with robust variable step-size filtered-x-least-mean-square (RVSS-FXLMS) algorithm. The applied RVSS-FXLMS filtering algorithm is a combination of the RVSS convergence and FXLMS algorithms. The control signal generated by the AHSC as an anti-error input can effectively suppress the tracking errors arising from vibration disturbance. The experimental results demonstrate that the AHSC can successfully improve the tracking performance on an existing architecture of the DVD drives in a vehicular system. More precisely, in severe disturbances the implemented hybrid system can still pick up data in high speed revolution, but not to decrease disk speed.