Effect of the end cap on the fragment velocity distribution of a cylindrical cased charge

The prediction of the fragment velocity distribution of a cylindrical cased charge with end caps is one of the key issues to assess the damage efficiency of the warhead. However, limited work has been con-ducted to predict the fragment velocity distributions along the axis of cylindrical cased charges with end caps. This paper presents a study of the velocity distribution of fragments caused by the explosion of a cylindrical cased charge with end caps. The fragment velocity distribution and the end cap velocity were determined by an X-ray radiography method, and the axial fragment distribution was determined by witness plates. It was found that the velocities of fragments, especially near the edge, were increased when the end caps were added, and the position of maximum velocity is closer to the non-detonation end. The fragment velocities were increased, and the fragment projection range was decreased with the increase of the thickness of the end cap. A formula for fragment velocity distributions of a cylindrical cased charge with end caps, which is based on Huang's formula, was proposed by the theoretical analysis and data fitting and validated experimentally. The results indicate that the proposed formula is accurate in predicting the fragment velocity distribution along the axis of a cylindrical cased charge with end caps detonated at one end.     

Background dominant colors extraction method based on color image quick fuzzy c-means clustering algorithm

A quick and accurate extraction of dominant colors of background images is the basis of adaptive camouflage design. This paper proposes a Color Image Quick Fuzzy C-Means (CIQFCM) clustering algorithm based on clustering spatial mapping. First, the clustering sample space was mapped from the image pixels to the quantized color space, and several methods were adopted to compress the amount of clustering samples. Then, an improved pedigree clustering algorithm was applied to obtain the initial class centers. Finally, CIQFCM clustering algorithm was used for quick extraction of dominant colors of background image. After theoretical analysis of the effect and efficiency of the CIQFCM algorithm, several experiments were carried out to discuss the selection of proper quantization intervals and to verify the effect and efficiency of the CIQFCM algorithm. The results indicated that the value of quantization intervals should be set to 4, and the proposed algorithm could improve the clustering efficiency while maintaining the clustering effect. In addition, as the image size increased from 128 × 128 to 1024 × 1024, the efficiency improvement of CIQFCM algorithm was increased from 6.44 times to 36.42 times, which demonstrated the significant advantage of CIQFCM algorithm in dominant colors extraction of large-size images.     

Ricochet quantification using a multiple sensor approach

This study investigates the ricochet behaviour of three different small-arms projectile types using a novel ricochet measuring device.The results can be used to estimate the danger potential of ricochets on shooting ranges.A ricochet is the change of direction and velocity of a projectile after impacting an oblique surface.This impact produces strong vibrations on a rigid plate.During this impact,flexural waves travel radially outwards from the point of impact.These waves are used to determine the properties of the impactor with accelerometers situated on the target surface.With the use of two measurement plates,one can produce a ricochet and detect the velocity at the same time.Accelerometers are suitable for accurate momentum measurements of single impacts.However,depending upon strike velocity and the impact angle,a ricochet can separate in multiple fragments after being deflected.From the operational safety perspective,these fragments need to be detected,as well.The approach of a coupled sensor concept was chosen to solve this problem.Thermographic sensors were additionally used to visualise the heat which is produced after pene-trating a rubber layer pasted in front of the steel target plate.With this approach one was able to detect the position of impact.The investigations showed that the measurement system performance is better with a multiple sensor design,which includes accelerometers for the velocity,impact strength and partly the position measurement,while the thermographic sensor was used for the position measurement and partly the momentum measurement.The investigated ammunition showed plausible fragmentation behaviour,and the results can already be used to estimate the danger potential of different ammunition types.Frangible projectiles fragment to small particles already after being deflected under a small angle.However,Full Metal Jacket projectiles with or without a steel core do not fragment under angles which are less than 5°.The objective of the paper is to demonstrate the possibility of measuring the complex ricochet me-chanics of small projectiles using standard accelerometers with the adequate signal processing approach.This measuring system is supported by an off the shelf thermographic camera.     

Power,polarity, and prudence: the ambiguities and implications of UK discourse on a multipolar international system

What do UK policymakers mean when they say that Britain’s strategic environment is returning to “multipolarity”? In realist international theory, polarity is a specific causal concept; the number of powers capable of balancing even the most capable other state(s) in the international system (“poles”) is taken to determine the system’s stability. Does the post-2017 appearance of polarity references in British security policy documents therefore reflect some unexpected UK renaissance of realist thought? Or is something else going on, as recent work by Ben Zala suggests? This article will demonstrate that, while UK official usage of the “multip–” word has indeed flourished recently, the term is actually being used in a more elastic, less bounded way than realism prescribes in order to generate other kinds of political effect. Specifically, “polarity” (and its “multi-” prefix) is used to characterise the behaviour of those major states that oppose Western-preferred international order, to elide Britain’s own relative power/status tensions, and to capture an expansive laundry-list of perceived international dangers. The article then discusses five ways in which a shift in polarity could negatively affect Britain; important consequences that merit preparatory contemplation, yet that an imprecise, catch-all understanding of “multipolarity” too readily obscures.     

Organizing for the ‘gray zone’ fight: early Cold War realities and the CIA’s Directorate of Operations

ABSTRACT

Despite its portrayal as something new, the concept of the ‘gray zone’ is not novel. It was the Cold War battleground in which the USA and the Soviet Union waged rival unconventional campaigns, and it was there that the newly formed Central Intelligence Agency (CIA) was given responsibility for operating. This was not the organization’s original purpose, but Cold War exigencies forced Washington to improvise and build an organization with unique capabilities. These early years shaped the CIA’s operations directorate, creating two distinct cultures within the larger agency, one focused on intelligence collection and the other focused on covert action.     

The Ethics of Cyber Attack: Pursuing Legitimate Security and the Common Good in Contemporary Conflict Scenarios

ABSTRACT

Cyber attack against Critical National Infrastructure is a developing capability in state arsenals. The onset of this new instrument in national security has implications for conflict thresholds and military ethics. To serve as a legitimate tool of policy, cyber attack must operate in accordance with moral concerns. To test the viability of cyber attack, this paper provides a new perspective on cyber ethics. Cyber attack is tested against the criteria of the common good. This involves identifying the four core components of the common good from a conflict perspective: respect for the person; social wellbeing; peace and security; and solidarity. The fate of these components is assessed in relation to the six key characteristics of cyber attack from a moral standpoint: security; the role or absence of violence; discrimination; proportionality; cyberharm; and the threshold of conflict. It is concluded that the common good must be incorporated into developing state cyber strategies.     

Systems failure: the US way of irregular warfare

ABSTRACT

Since 9/11, the United States has achieved notable gains against al Qaeda, and also Islamic State (IS), all while avoiding another mass-casualty attack at home. Yet, institutionally, culturally, and in its capabilities, the US government remains seriously ill-equipped for the task of countering irregular threats. Partly as a result, Islamist extremism shows no sign of being defeated, having instead metastasized since 9/11 and spread. Why, given the importance accorded to counterterrorism, has the US approach remained inadequate? What is impeding more fundamental reforms? The article evaluates the United States’ way of irregular warfare: its troubled engagement with counterinsurgency and its problematic search for lower cost and lower risk ways of combating terrorism. It suggests needed reforms but acknowledges also the unlikelihood of change.