A compact wideband bandpass filter with a wide passband and very‐wide out‐of‐band suppression is presented. The filter is constructed from a central rectangular‐ring resonator with two open stubs ...placed around it symmetrically. In addition, tri‐section stepped‐impedance resonators are symmetrically distributed on both sides of the two open stubs, and two symmetrical funnel‐shaped resonators are included to enhance out‐of‐band suppression. The out‐of‐band performance of filter is very good, with a suppression level greater than 20 dB up to 25.72 GHz. The center frequency of the filter is 5.84 GHz, with a fractional bandwidth of 115.8%. Good agreement between the simulations and measurements validates the design principle.
Wireless sensor networks (WSNs) are composed of a large number of sensor nodes, typically powered by batteries. Once the energy is exhausted, the sensor nodes will stop working, which will have a ...serious impact on network performance. Therefore, energy consumption has always been a bottleneck in the development of WSNs. To balance the network energy and improve energy efficiency, this article proposes a clustering routing protocol based on tuna swarm optimization and fuzzy control theory (TSFC). First, tuna swarm optimization (TSO) is utilized to optimize network clustering by considering the average and standard deviation of distances from nodes to their respective cluster centers, which improves the compactness of cluster structure. Therefore, communication distance within the cluster is reduced, thereby reducing the energy consumption of communication within the cluster. Then, in the cluster head (CH) selection stage, a fuzzy controller for selecting CHs is designed based on the fuzzy control theory. The residual energy of nodes, distance to the base station (BS), and average distance to other nodes in the cluster are taken as inputs for the fuzzy controller, which outputs a fitness value of the node to become the CH. This method optimizes the CH selection, thereby reducing node energy consumption and balancing network energy consumption. Simulation results demonstrate that the proposed protocol can reduce network energy consumption, improve energy efficiency, and balance network energy. Furthermore, the network lifetime is 45.9%, 33.5%, and 10.0% longer than that of gray wolf optimization (GWO-C), energy-efficient LEACH (EE-LEACH), and enhanced fuzzy-based LEACH (E-FLEACH), respectively.
Wireless sensor networks (WSNs) are composed of a large number of spatially distributed sensor nodes to monitor and transmit information from the environment. However, the batteries used by these ...sensor nodes have limited energy and cannot be charged or replaced due to the harsh deployment environment. This energy limitation will seriously affect the lifetime of the network. Therefore, the purpose of this research is to reduce energy consumption and balance the load of sensor nodes by clustering routing protocols, so as to prolong the lifetime of the network. First, the coronavirus herd immune optimizer is improved and used to optimize the network clustering. Second, the cluster heads (CHs) are selected according to the energy and location factors in the clusters, and a reasonable CH replacement mechanism is designed to avoid the extra communication energy consumption caused by the frequent replacement of CHs. Finally, a multihop routing mechanism between the CHs and the base station is constructed by Q-learning. Simulation results show that the proposed work can improve the structure of clusters, enhance the load balance of nodes, reduce network energy consumption, and prolong the network lifetime. The appearance time of the first energy-depleted node is delayed by 25.8%, 85.9%, and 162.2% compared with IGWO, ACA-LEACH, and DEAL in the monitoring area of Formula Omitted m, respectively. In addition, the proposed protocol shows better adaptability in varying dynamic conditions.
Objective. To investigate the feasibility and correlation of sacroiliac joint (SIJ) fat fraction (FF) and R2∗ as markers of bone metabolism in patients with ankylosing spondylitis (AS). Methods. 75 ...AS patients were classified into an early active group (EA), late active group (LA), and inactive group (IA). Additionally, 54 matched healthy individuals were selected to be part of the normal control group (NC). All participants underwent chemical shift encoded based MRI (IDEAL-IQ) and routine clinical SIJ MRI at 3.0 T. FF and R2∗ were measured in subchondral bone, bone marrow edema (BME), and fat metaplasia (FM). Out of the participants, 39 with BME lesions (15 from EA, 16 from LA, 8 from IA) and 39 with FM lesions (9 from EA, 17 from LA, 13 from IA) were included. Differences in FF, R2∗ value for subchondral bone of all participants and for BME, FM lesions were evaluated. Subsequently, different stages of BME and FM in patient groups were compared, and the relationship between FF and R2∗ was analyzed. Results. A significant difference in FF was demonstrated among the BME, FM and the normal bone marrow (p<0.001), meanwhile, the difference of R2∗ value in FM was significantly lower (p=0.034, 0.012) than that of BME and that of normal bone marrow. At lever of different lesions, only the FF for BME was significantly different among 3 patient groups (p=0.001), while there was no significantly different FF for FM among 3 patient groups. Unlike in BME lesions, the FF in FM lesions had a negative correlation with R2∗ (p<0.001, r=−0.488). Conclusion. FF and R2∗ measurements help to quantitatively analyze the bone marrow fat composition and bony trabecular microstructure changes in AS, providing a noninvasive and accurate assessment basis for AS bone metabolism abnormalities.
The change of dielectric properties of epoxy/anhydride systems during eleven months storing was investigated. Test systems were bisphenol-A epoxy cured by different content of ...methyl-hexahydrophthalic anhydride with a slow cooling process across Tg range included in their curing procedure to reduce residual stress. The results showed all the systems’ dielectric constant and dielectric loss angle tangent had a trend of down then up. The highest decreasing amplitudes were about 4% and 10% respectively. Possible explanations for these phenomena were proposed, and then some preliminary investigations were carried out like DSC and IR.
The influence of 60Co gamma-ray irradiation on the chemical compositions and properties of an epoxy encapsulant was investigated. The total irradiation dose varied from 0.1 kGy to 100 kGy with a ...fixed dose rate of 500 Gy/h. Fourier transform infrared spectra, X-ray photoelectron spectroscopy analysis and discoloration proved the occurrence of oxidation caused by the irradiation. Tg and density remained unchanged owing to the competing effects of irradiation-induced degradation and crosslinking. The tensile strength, impact strength and electrical strength did not decrease distinctly until the irradiation dose reached above 11 kGy. Rubbery coefficient of linear thermal expansion (CTE), relative permittivity and dissipation factor, on the contrary, were more sensitive to the oxidation and increased sharply when the irradiation dose was only 0.1 kGy. Our results suggested that the evolution of CTEs and dielectric properties could affect the long-term application and reliability of the epoxy encapsulant in the irradiative environment.
In this paper, the partner selection problem with a due date constraint in virtual enterprises is proved to be an NP-complete problem. So it cannot have any polynomial time solution algorithm at ...present. A nonlinear integer programming model for this problem is established. The objective function and a constraint function of the model have monotone properties. Based on the above observations, a Branch & Bound algorithm is constructed to solve the problem. Numerical experiments show that the algorithm is efficient.
A Design for Clock Synchronization Using CPPLL Wang, Xiao; Zeng, Zhi Bin
Applied Mechanics and Materials,
03/2014, Letnik:
543-547, Številka:
Vehicle, Mechatronics and Information Technologies II
Journal Article
Recenzirano
High performance clock synchronization system is essential in communication transmission, which is based on the principle of phase locked loop synchronization that tracking a high accuracy, high ...stability reference clock source usinh low-pass filter to turn the value into voltage and to control VCO or VXCO and makes the output frequency and the input frequency to maintain strict synchronization.
To introduce an arthroscopic technique in managing recurrent dislocation of the patella and its clinical results.
Sixteen patients with recurrent patellar dislocation were reviewed, including 3 males ...and 13 females. The average age was 17.6 years old (ranged from 14 to 32 years). The patients suffering from patellar sub-luxation averaged 18.5 months (ranged from 6 to 23 months)before operation. These patients were treated with lateral patellar retinacular release outside the synovial bursa of knee joint and medial patellofemoral ligament reconstruction using the semitendinosus tendon free autograft. The Lyshohm scores before and after operation were used to evaluate outcomes at the final follow-up.
All the patients were followed up, and the duration ranged from 6 to 48 months, with an average of 12 months. There was no recurrence. The Q angle decreased from (16.4 ± 3.7)° to (10.1 ± 1.4)°; insall index decreased from 1.37 ± 0.25 to 1.28 ± 0.23; congruence angle decreased from (21.3 ± 2.6)° to (5.86 ± 2.23)°; L
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