Principle Of Cancellation Research Articles

Novel design of microstrip antenna array with low scattering performance

In this paper, the idea of electromagnetic surface (EMS) is introduced into the design of microstrip antenna array. The antenna element proposed in this paper is treated as an EMS element, whose reflection characteristics are taken into consideration in the process of antenna array design. Firstly, a rectangular patch antenna element is designed. Then, by cutting arc-shaped structure into a rectangular patch, another element is created to generate 180° ± 30° effective phase difference compared with original antenna element. As a consequence, 180° ± 30° effective phase difference is obtained from 5.5 GHz to 6.9 GHz for the <i>y</i>-polarized incidence. Meanwhile, for the <i>x</i>-polarized incidence, each of the two elements possesses high absorptivity over the operating frequency as a result of matching load. Besides, the two elements work in the same resonant mode and the same resonant frequency band when treated as radiators. In order to further explain the consistency in radiation and difference in reflection between the two structures, current distribution at 5.8 GHz is investigated in terms of radiation and reflection. Then, the two elements are arranged into a chessboard array to achieve the low scattering performance based on phase cancellation principle under the <i>y</i>-polarized incidence. Based on the absorption principle, the matching load is added to improve the scattering performance of the composite antenna array with the <i>x</i>-polarized incidence. Simultaneously, the proposed antenna array maintains good radiation characteristics due to the consistency between the radiation performances of the two elements. The corresponding antenna array is fabricated and tested. Simulated and measured results prove that the proposed antenna array also achieves good radiation performance. And a 6 dB radar cross section reduction is obtained from 5.6 to 6.2 GHz under the <i>x</i> polarization and from 5.5 to 7.0 GHz under the <i>y</i> polarization for the normal incident wave, implying 10.1% and 24% in relative bandwidth, respectively. In-band reflection suppression in the specular direction is demonstrated for an incident angle of 30° under both polarizations. The measured results are in good agreement with the simulated ones. Additionally, the approach proposed in this paper offers an effective way to deal with the confliction between radiation and scattering performance, and can also be applied to other kinds of antenna arrays.

Enhancing security of SIC algorithm on non-orthogonal multiple access (NOMA) based systems

Non-orthogonal multiple access (NOMA) is a promising candidate among potential nominees for future radio access. NOMA adopts the principle of successive interference cancellation (SIC) algorithm at the receiver’s side to segregate user’s information. However, during SIC process, information of the user(s) with weaker channel gain is extracted by user(s) with stronger channel gain. It can raise major security concerns, e.g. session hijacking, eavesdropping, identity theft, and others, for users with weaker channel gains. Therefore, this research aims to analyze and verify a secure SIC algorithm for NOMA based systems. This research proposes and demonstrates the SIC scheme to enhance security on the user’s side by making use of MAC address and IMEI that are devoted to a smartphone as distinctive keys. This research shown that the proposed scheme can improve security in terms of confidentiality time and secrecy capacity.

Ultra-wideband low radar cross-section metasurface and its application on waveguide slot antenna array** Project supported by the National Natural Science Foundation of China (Grant Nos. 61671464, 61701523, and 61471389).

A novel approach devoted to achieving ultra-wideband radar cross section reduction (RCSR) of a waveguide slot antenna array (WGSAA) while maintaining its radiation performance is proposed. Three kinds of artificial magnetic conductors (AMCs) tiles consisting of three types of basic units resonant at different frequencies are designed and arranged in a novel quadruple-triangle-type configuration to create a composite planar metasurface. The proposed metasurface is characterized by low radar feature over an ultra-wideband based on the principle of phase cancellation. Both simulated and measured results demonstrate that after the composite metasurface is used to cover part of the antenna array, an ultra-wideband RCSR involving in-band and out-of-band is achieved for co- and cross-polarized incident waves based on energy cancellation, while the radiation performance is well retained. The proposed method is simple, low-cost, and easy-to-fabricate, providing a new method for ultra-wideband RCSR of an antenna array. Moreover, the method proposed in this paper can easily be applied to other antenna architectures.

A study on the Governing Law Clause of Shipbuilding Contract from the Viewpoint of Private International Law - Review on the Supreme Court May 30, 2017 Decision 2014Da233176 -

국제사법은 제1조에서 외국적 요소가 있는 법률관계에 관한 준거법을 정함을 목적으로 한다고 규정하여 외국적 요소가 있는 법률관계를 국제사법의 규율대상으로 하면서도, 한편으로는 제25조 제4항에 따라 순수한 국내계약에 대하여 당사자가 다른 국가의 법을 선택할 수 있도록 하여 순수한 국내계약에 적용될 법에 대하여도 언급하고 있다. 그런데 현실에 있어서는 내국인이 조세피난처에 설립한 특수목적법인과 국내법인 사이의 계약과 같이 외국적 요소를 인정하는 것이 합리적인지 여부가 문제되는 경우가 발생하는바, 이러한 경우 계약에 외국적 요소가 존재함을 이유로 곧바로 국제사법의 적용대상으로 볼 것인지 아니면 이를 순수한 국내계약에 준하여 다룰 것인지가 문제된다. 나아가 이러한 사안에서 당사자가 다른 나라의 법을 선택하도록 하는 준거법 약정을 한 경우, 당사자의 준거법 선택이 외국법의 준거법으로서의 채택인지 아니면 사적자치에 의하여 외국법의 내용을 계약의 내용으로 편입시키고자 한 것인지에 대한 해석의 문제가 발생한다. 대상판결(대판 2017. 5. 30. 2014다233176)은 양 당사자 중 일방이 외국국적의 특수목적법인인 점이 유일한 외국적 요소인 사건에서 외국적 요소를 당연히 인정한 후 국제사법을 적용하였다. 이를 바탕으로 선박건조계약상 준거법에 관한 조항이 있음을 이유로 당사자가 영국법을 준거법으로 채택하였다고 하면서 영국 계약법상 법정해제의 법리와 영국판례를 판단의 근거로 삼았다. 그런데 이 사건의 외국적 요소가 상당한 정도에 이르러 국제사법을 적용하는 것이 당연히 합리적이고 타당한지에 대하여는 의문이 들고, 나아가 이 사건 선박건조계약상 준거법에 관한 조항을 영국법의 준거법으로서의 저촉법적 지정이라고 본 대법원의 판단은 “양 당사자는 본 계약과 그 각 조항의 효력 및 해석에 대하여 영국법을 준거법으로 한다”고 하는 계약상 준거법 조항의 문구에 비추어 볼 때 받아들이기 어려운 측면이 있다. 따라서 본 논문에서는 선박건조계약상 준거법 지정 조항의 국제사법적 의미에 대한 검토를 통하여 대상판결을 비판적으로 고찰하는 한편 대상판결의 준거법으로서 국내법이 적용됨이 타당하다는 필자의 견해를 바탕으로 대상사건을 재검토해 보고자 한다.The Act on Private International Law (hereinafter the “Act”), in its Article 1, provides that its purpose is to determine governing laws of the legal relations which contain foreign factors, thus covering legal relations with foreign factors in its applicability, but at the same time, in its Article 25 (4), allows the parties to choose the laws of another country in pure domestic contracts, thus also referring to laws applicable to pure domestic contracts. In reality, however, there are cases causing controversy on whether foreign factors can be recognized (e.g., contract between a special purpose company incorporated by a domestic person in a tax haven and a domestic corporation), in which case there is the issue of whether the relevant contract shall be directly covered by the Act on the ground of its foreign factors or shall be treated like a pure domestic contract. Further, if in such cases the parties agree to choose the law of any other country as governing law, there is an interpretational issue of whether the parties’ choice of governing law shall be deemed designation of foreign law as governing law or shall be deemed incorporation, by reference, of foreign law into the contract based on the principle of the parties’ autonomy. The Supreme Court’s decision (Supreme Court Decision May 30, 2017, Case No. 2014Da233176), in a case whose sole foreign factor was one of the parties being a foreign special purpose company, readily recognized the foreign factor and then applied the Act. Then the court, on the ground that the shipbuilding contract had governing law clause, held that the parties chose the laws of England as governing law, and based its conclusion on the legal principle of statutory cancellation of contract in English Contract Law and the English judicial precedents. However, there are doubts on whether this case has a proximate degree of foreign factor and therefore applying the Act is naturally reasonable and justified. Further, given the language of the governing law clause in the shipbuilding contract of this case “The parties hereto agree that the validity and interpretation of this Contract and of each Article and part thereof shall be governed by the laws of England”, the Supreme Court’s determination that the governing law clause has designated the laws of England as proper law may be difficult to accept. So, this article will critically examine the decision by reviewing choice-of-law meaning or significance of the shipbuilding contract’s governing law clause and at the same time review this case based on the author’s position that it is reasonable to apply domestic law (Korean law) as the governing law of this case.

Design of multi-band metasurface antenna array with low RCS performance**Project supported by the National Natural Science Foundation of China (Grant Nos. 61471389, 61701523, and 61671464).

In this paper, a multi-band metasurface (MS) antenna array with low radar cross section (RCS) performance is proposed and measured. Firstly, a 4 × 4 antenna array is composed of four 2 × 2 Jerusalem cross structure antenna arrays working at different frequency bands, which is aimed at enhancing the bandwidth effectively. Then, each antenna can be seen as a unit of MS in spite of adding the feeding structure. Based on phase cancellation principle, the MS is arranged into a chessboard configuration in order to realize wideband RCS reduction. Thus, excellent radiation and scattering characteristics are obtained simultaneously. Simulated and measured results indicate that this work provides a novel method to achieve bandwidth expansion as well as wideband RCS reduction of the antenna array.

Mantle Cloaks Based on the Frequency Selective Metasurfaces Designed by Bayesian Optimization

We propose a full optimization procedure for designing mantle cloaks enclosing arbitrary objects, using sub-wavelength conformal frequency selective surface (FSS). Rely on the scattering cancellation principle of mantle cloak characterized by an average surface reactance, a personal computer can achieve this design procedure. By combing a Bayesian optimization (BO) with an electromagnetic solver, we can automatically find the optimal parameters of a conformal mantle cloak which can nearly cancel the scattering from the enclosed objects. It is shown that the results obtained by our method coincide with those from a rigorous analytical model and the numerical results by full parametric scanning. The proposed methodology opens up a new route for realizing ultra-wideband illusion scattering of electromagnetic wave, which is important for stealth and microwave applications.

Low RCS and broadband metamaterial‐based low‐profile antenna using PCM

In this study, a novel cross layout of polarisation conversion metamaterial (PCM) is investigated for the first time. Based on the principle of phase cancellation, the cross structure can reduce radar cross section (RCS) significantly over a wider band compared with the chessboard configuration. The low-profile metamaterial-based antenna is composed of the cross PCM structure and a driven patch sandwiched between the PCM patches and the ground plane. Simulated and measured results show that compared with the microstrip patch antenna, the proposed antenna can achieve a wider impedance bandwidth of 6.05-7.52 GHz (21.7%) and milder gain variation in the working band, while the monostatic RCS can be reduced over 5.8-18.0 GHz (102.5%).

Backscattered EM-wave manipulation using low cost 1-bit reflective surface at W-band

The design of low cost 1-bit reflective (non-absorptive) surfaces for manipulation of backscattered EM-waves and radar cross section (RCS) reduction at W-band is presented in this article. The presented surface is designed based on the reflection phase cancellation principle. The unit cell used to compose the proposed surface has an obelus (division symbol of short wire and two disks above and below) like shape printed on a grounded dielectric material. Using this unit cell, surfaces that can efficiently manipulate the backscattered RCS pattern by using the proposed obelus-shaped unit cell (as ‘0’ element) and its mirrored unit cell (as ‘1’ element) in one surface with a 180° ± 35° reflection phase difference between their reflection phases are designed. The proposed surfaces can generate various kinds of backscattered RCS patterns, such as single, three, or four lobes or even a low-level (reduced RCS) diffused reflection pattern when those two unit cells are distributed randomly across the surface aperture. For experimental characterization purposes, a 50 × 50 mm2 surface is fabricated and measured.

Wideband Gain Enhancement and RCS Reduction of Fabry–Perot Resonator Antenna With Chessboard Arranged Metamaterial Superstrate

The simultaneous improvement in radiation and scattering performance of an antenna is normally considered as contradictory. In this paper, wideband gain enhancement and radar cross section (RCS) reduction of Fabry–Perot (FP) resonator antenna are both achieved by using chessboard arranged metamaterial superstrate (CAMS). The CAMS is formed by two kinds of frequency-selective surfaces. The upper surface of CAMS is designed to reduce RCS based on the phase cancellation principle, and the bottom surface is used to enhance antenna gain on the basis of FP resonator cavity theory. Both simulation and measured results indicate that compared with primary antenna, the gain of the proposed FP resonator antenna is enhanced by 4.9 dB at 10.8 GHz and the 3 dB gain bandwidth is from 9.4 to 11.1 GHz (16.58%). Meanwhile, the RCS of the proposed FP resonator antenna is reduced from 8 to 18 GHz, with peak reduction of 39.4 dB. The 10 dB RCS reduction is obtained almost from 9.6 to 16.9 GHz (55.09%) for arbitrary polarizations. Moreover, the in-band RCS is greatly reduced, owing to the combined effect of CAMS and FP resonator cavity.

Interpreting the Infinitesimal Mathematics of Leibniz and Euler

We apply Benacerraf's distinction between mathematical ontology and mathematical practice (or the structures mathematicians use in practice) to examine contrasting interpretations of infinitesimal mathematics of the 17th and 18th century, in the work of Bos, Ferraro, Laugwitz, and others. We detect Weierstrass's ghost behind some of the received historiography on Euler's infinitesimal mathematics, as when Ferraro proposes to understand Euler in terms of a Weierstrassian notion of limit and Fraser declares classical analysis to be a "primary point of reference for understanding the eighteenth-century theories." Meanwhile, scholars like Bos and Laugwitz seek to explore Eulerian methodology, practice, and procedures in a way more faithful to Euler's own. Euler's use of infinite integers and the associated infinite products is analyzed in the context of his infinite product decomposition for the sine function. Euler's principle of cancellation is compared to the Leibnizian transcendental law of homogeneity. The Leibnizian law of continuity similarly finds echoes in Euler. We argue that Ferraro's assumption that Euler worked with a classical notion of quantity is symptomatic of a post-Weierstrassian placement of Euler in the Archimedean track for the development of analysis, as well as a blurring of the distinction between the dual tracks noted by Bos. Interpreting Euler in an Archimedean conceptual framework obscures important aspects of Euler's work. Such a framework is profitably replaced by a syntactically more versatile modern infinitesimal framework that provides better proxies for his inferential moves. Keywords: Archimedean axiom; infinite product; infinitesimal; law of continuity; law of homogeneity; principle of cancellation; procedure; standard part principle; ontology; mathematical practice; Euler; Leibniz

Radar Cross Section Reduction of a Microstrip Antenna Based on Polarization Conversion Metamaterial

A novel method aimed at reducing radar cross section (RCS) under incident waves with both $x$ - and $y$ -polarizations, with the radiation characteristics of the antenna preserved, is presented and investigated. The goal is accomplished by the implementation of the polarization conversion metamaterial (PCM) and the principle of passive cancellation. As a test case, a microstrip patch antenna is simulated and experimentally measured to demonstrate the proposed strategy for dramatic radar cross section reduction (RCSR). Results exhibit that in-band RCSR is as much as 16 dB compared to the reference antenna. In addition, the PCM has a contribution to a maximum RCSR value of 14 dB out of the operating band. With significant RCSR and unobvious effect on the radiation performance of the antenna, the proposed method has a wide application for the design of other antennas with a requirement of RCS control.

Design of Background Noise Suppression Circuit for Mobile Phones

With the purpose of reducing the influence of background noise on the call quality of mobile phones, background noise suppression circuit is designed based on the principle of self-adaptive noise cancellation. Because this method is not involved in the nature of the noise itself, it can be used both for stationary noise cancellation and quasi-stationary noise cancellation. The working principle and circuit design of the system are introduced in detail. Simulated experiment was conducted in the lab, and its experimental results were analyzed. The experimental results show that the circuit works well with low cost, and has a broad prospect of application and popularization.

Dual-Channel Forward-Looking SAR Micro-Motion Targets Detection

It is aimed at the problem of forward-looking SAR micro-motion target detection in this paper. The traditional dual-channel SAR DPCA cancellation principle is analyzed and a dual-channel DPCA model of forward-looking SAR is proposed, the amplitude and phase characters of the signal after DPCA cancellation is studied, the distance domain of the micro-motion target is determined, then the micro-motion target detection is probability under different echo SNR with Monte-Carlo Operation, when the echo SNR is bigger than -5dB,and the target detection probability is greater than 90%.

Refined Definitions in Real Numbers and Vectors and Proof of Field Theories

A set of new and refined principles and definitions in Real Numbers and Vectors are presented. What is a Vector? What is the meaning of the Addition of two Vectors? What is a Real Number? What is the meaning of their signs? What is the meaning of the Addition of two Real Numbers? What is the Summation Principle in Addition Operation? What is the Cancellation Principle in Addition Operation? What is the Meaning of the Multiplication of two Real Numbers? Is Field Theory a law? Can it be proved? All these issues are addressed in this paper. With better pictures and graphical presentations, proof of Field Theories in Real Numbers and Vectors including Commutativity, Associativity and Distributivity are also proposed.

Behavioral economics

Behavioral economics uses evidence from psychology and other social sciences to create a precise and fruitful alternative to traditional economic theories, which are based on optimization. Behavioral economics may interest some biologists, as it shifts the basis for theories of economic choice away from logical calculation and maximization and toward biologically plausible mechanisms.

A 2.5-GHz Direct Digital Frequency Synthesizer with spurious noise cancellation

A 2.5 GHz Direct Digital Frequency Synthesizer (DDS) with spurious noise cancellation is presented. Seven auxiliary DDSs have been used as spur cancellers which can generate opposition signal to counteract the spurs in DDS’s output spectrum. Principle of spur cancellation and its implementation scheme is discussed. Key steps of spur cancellation procedure are also described. This DDS is implemented in a 0.18 µm CMOS technology, occupies 4.6 mm × 4.2 mm including bond pads. Measured performance is SFDR > 58 dB for output signal frequencies up to 1 GHz, more than 20 dB’s improvement is achieved comparing to its intrinsic SFDR performance.

Study on Jamming to Sidelobe Cancellation of Phased-Array Radar

Antenna sidelobe cancellation is effective method to repress radar sidelobe jamming. This paper analysed the function and characteristics completely based on the principle of sidelobe cancellation, and look for jamming method more effective according to the weakness and technique crux. The results indicate that the adaptive side lobe cancellation technique can effectively antagonize the active jamming.

Sliding mode control of DC/DC converters

Sliding mode control algorithms for buck and boost power converters are surveyed in the paper. Current and voltage controls are demonstrated for the both cases. It is shown, that direct voltage control for a boost converter results in unstable zero dynamics. Chattering suppression based on harmonic cancellation principle along with switching frequency control is demonstrated.

System Identification and Control of FOPDT or SOPDT Processes

A relay feedback identification autotuning PID/PI is proposed in this paper which is capable of controlling long time-delay processes. The real process is approximated via FOPDT or SOPDT models, whose parameters are specified through a modified relay feedback identification method. Applying zero-pole cancellation principle, the PID/PI is tuned according to the specified amplitude and phase margins. Model identification and controller parameter tuning are done on-line without much influence on the normal operation.

Artinian level algebras of codimension 3

In this paper, we continue the study of which h -vectors H = ( 1 , 3 , … , h d − 1 , h d , h d + 1 ) can be the Hilbert function of a level algebra by investigating Artinian level algebras of codimension 3 with the condition β 2 , d + 2 ( I lex ) = β 1 , d + 1 ( I lex ) , where I lex is the lex-segment ideal associated with an ideal I . Our approach is to adopt a homological method called the Cancellation Principle: the minimal free resolution of I is obtained from that of I lex by canceling some adjacent terms of the same shift. We prove that when β 1 , d + 2 ( I lex ) = β 2 , d + 2 ( I lex ) , R / I can be an Artinian level k -algebra only if either h d − 1 < h d < h d + 1 or h d − 1 = h d = h d + 1 = d + 1 holds. We also show that for H = ( 1 , 3 , … , h d − 1 , h d , h d + 1 ) , the Hilbert function of an Artinian algebra of codimension 3 with the condition h d − 1 = h d < h d + 1 , (a) if h d ≤ 3 d + 2 , then h -vector H cannot be level, and (b) if h d ≥ 3 d + 3 , then there is a level algebra with Hilbert function H for some value of h d + 1 .