Adjacent Partitioning Research Articles

Numerical study of the effect of gender composition and partitioning boards on evacuation in a two-line transfer transit rail subway station

Subways for transit rail can solve urban congestion problems. Many people use transit rail subways during rush hours. Taking Jinan Wangfuzhuang subway station as the research object, the influence of different gender compositions on the evacuation process was analysed and discussed in this study. The results show that the evacuation efficiency of passengers that include a high proportion of males in subway stations is higher than that for passengers with a high proportion of females with the same age composition. According to the field observation and numerical calculation results, congestion readily occurred at the subway station exits and automatic ticket gates, and partitioning boards are added to alleviate congestion. Adding partitioning boards at automatic ticket gates can shorten the evacuation time. The calculated critical length of a partitioning board is 1.5 m, and the evacuation time can be shortened by 9.6% compared with the case without partitioning boards. Additionally, the evacuation time can be shortened by installing partitioning boards at exits. The results show that when the length of partitioning boards at exits is 1.5 m, the critical distance between adjacent partitioning boards is 1.5 m, and the evacuation time can be shortened by 16.9% compared with the case without partitioning boards.

A PTS Technique With Non-Disjoint Sub-Block Partitions in M-QAM OFDM Systems

This paper presents a modified partial transmit sequence (PTS) algorithm for peak-to-average power ratio (PAPR) reduction of M-QAM orthogonal frequency division multiplexing (OFDM) signals by partitioning an OFDM block into non-disjoint OFDM sub-blocks. Since an M-QAM constellation can be written as sum of several QPSK constellations, we can then apply different disjoint partitions on the QPSK OFDM blocks, which result in an equivalent non-disjoint partition on the M-QAM OFDM block. Compared to a disjoint sub-block partition in conventional PTS, simulation results show that the modified PTS with a non-disjoint partition achieves better PAPR reduction in adjacent, interleaved, and random partitioning schemes.

PAPR Reduction in OFDM Signal by Incorporating Mu-Law Companding Approach into Enhanced PTS Scheme

AbstractOrthogonal Frequency Division Multiplexing (OFDM) is a potential transmission approach for high capacity communication systems. Despite the many advantages of OFDM, the major downside is the high peak-to-average power ratio (PAPR) which increases the system complexity, reduces the efficiency of the system, causes degradation in BER performance, and makes OFDM sensitive to nonlinear distortion in the transmission. Various methods have been proposed to deal with the PAPR problem, including the partial transmit sequence (PTS) that has attracted considerable attention. Hence, this paper presents a hybrid approach combining an enhanced PTS technique with Mu-Law companding. The PTS technique was enhanced through improving its sub-block partitioning scheme, where the enhanced partitioning scheme consolidated a conventional interleaved partitioning into an adjacent partitioning scheme. This incorporation of Mu-Law characteristic in time domain for PAPR reduction in OFDM essentially enhances the PAPR reduction performance, based on using numerical simulation results. Consequently, though the pseudorandom sub-block partition method obtains better PAPR reduction more than the other sub-block partition schemes (interleaved and adjacent) of ordinary PTS, it is quite difficult to be designed. The findings show that the enhanced PTS technique with Mu-Law companding, while maintaining low computational complexity, performs significantly better than the pseudorandom partitioning PTS on various types of modulation formats and subcarriers.

Performance analysis of OFDM receiver with modified PTS technique

Modified partial transmit sequence PTS technique with adjacent partitioning and four phase factors is implemented to enhance the PAPR performance of OFDM system and its PAPR reduction performance is evaluated in terms of the complementary cumulative distribution function CCDF. A multipath fading environment is considered and the performance of the OFDM receiver is evaluated using least square LS and minimum mean square error MMSE channel estimation methods. The performance of the receiver is evaluated in terms of mean square error MSE and bit error rate BER. The performance of the OFDM receiver is enhanced with PAPR reduction.

PTS Method with Combined Partitioning Schemes for Improved PAPR Reduction in OFDM System

Although orthogonal frequency division multiplexing (OFDM) is an efficient wireless transmission system, it suffers from a crucial drawback namely high peak-to-average power ratio (PAPR) that limits transmitter power efficiency. Thus, different PAPR reduction algorithms have been introduced. Partial transmit sequence (PTS) is the most attractive solution which can provide good PAPR reduction performance without distortion. In any PTS system, partitioning of the OFDM frame into disjoint sub-blocks is a significant step. Out of the existing partitioning techniques, adjacent partitioning (AP) is a fairly simple partitioning scheme achieving efficient PAPR reduction performance. This paper presents an enhanced PTS approach that combines two PTS partitioning schemes, adjacent and interleaved partitioning, in order to effectively reduce the PAPR of OFDM systems. With an aim of determining the effects of length variability of adjacent partitions, we performed an investigation into the performances of a variable length adjacent partitioning (VL-AP) and fixed length adjacent partitioning in comparison with the enhanced PTS scheme.

Finite element study of a tissue-engineered cartilage transplant in human tibiofemoral joint

Most tissue-engineered cartilage constructs are more compliant than native articular cartilage (AC) and are poorly integrated to the surrounding tissue. To investigate the effect of an implanted tissue-engineered construct (TEC) with these inferior properties on the mechanical environment of both the engineered and adjacent native tissues, a finite element study was conducted. Biphasic swelling was used to model tibial cartilage and an implanted TEC with the material properties of either native tissue or a decreased elastic modulus and fixed charged density. Creep loading was applied with a rigid impermeable indenter that represented the femur. In comparison with an intact joint, compressive strains in the transplant, surface contact stress in the adjacent native AC and load partitioning between different phases of cartilage were affected by inferior properties of TEC. Results of this study may lead to a better understanding of the complex mechanical environment of an implanted TEC.

Conjugate Interleaved Partitioning PTS Scheme for PAPR Reduction of OFDM Signals

The interleaved partitioning partial transmit sequence (IP-PTS) scheme is an attractive technique for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems. But the PAPR performance of IP-PTS is inferior to that of the adjacent partitioning PTS (AP-PTS) scheme because the candidates generated in IP-PTS are not fully independent. This paper analyzes the independence of candidates in IP-PTS in detail and finds the effective phase factor vectors. In order to improve the PAPR performance of IP-PTS, a conjugate IP-PTS (C-IP-PTS) scheme is proposed. By performing the conjugate operations on some sub-blocks, the number of candidates is increased. Because of the conjugate property of the discrete Fourier transform (DFT), the additional inverse DFT can be avoided. By optimizing the conjugate sequence, the complexity can be further lowered. Simulation results show that C-IP-PTS can obtain better PAPR performance compared with AP-PTS; moreover, the computational complexity of C-IP-PTS is not high.

Enhanced interleaved partitioning PTS for peak-to-average power ratio reduction in OFDM systems

The independence of the candidates generated in the existing interleaved partitioning partial transmit sequences (IP-PTS) is first investigated. The result shows that these candidates are not fully independent, which leads to performance inferior to the adjacent partitioning PTS (AP-PTS) in which all the generated candidates are mutually independent. To improve the performance of the IP-PTS in peak-to-average power ratio reduction, a novel type of phase sequences for IP-PTS is proposed that can be used to produce fully independent candidates so that IP-PTS can achieve similar performance to AP-PTS, while keeping low complexity.