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Polyurea falls into a category of elastomeric co‐polymers in which, due to the presence of strong hydrogen bonding, the microstructure is of a heterogeneous nature and consists of a compliant/soft matrix and stiff/hard nanometer size hard domains. Recent investigations have shown that the use of polyurea as an external or internal coating/lining had substantially improved ballistic‐penetration resistance of metallic structures. The present work aims to use computational methods and tools in order to assess the shock‐mitigation ability of polyurea when used in the construction of different components (suspension‐pads, internal lining and external coating) of a combat helmet.

Shock‐mitigation capability of combat helmets has become an important functional requirement as shock‐ingress into the intra‐cranial cavity is known to be one of the main causes of traumatic brain injury (TBI). To assess the shock mitigation capability of polyurea, a combined Eulerian/Lagrangian fluid/solid transient non‐linear dynamics computational analysis of an air/helmet/head core sample is carried out and the temporal evolution of the axial stress and particle velocities (for different polyurea augmented helmet designs) are monitored.

The results obtained show that improvements in the shock‐mitigation performance of the helmet are obtained only in the case when polyurea is used as a helmet internal lining and that these improvements are relatively small. In addition, polyurea is found to slightly outperform conventional helmet foam, but only under relatively strong (greater than five atm) blastwave peak overpressures.

The present approach studies the effect of internal linings and external coatings on combat helmet blast mitigation performance.

The fabric construction of the ballistic fabrics used in military helmets is analyzed in this research and the ballistic performance of the fabric construction is compared. The advanced compact index Ψ_z is used in designing the construction of the ballistic fabrics used for military helmets. There is a relationship between the compact index of the fabric and its ballistic performance when this method is selected. Once the compact level of the fabric is grasped accurately, it raises the distinct thinking that antiballistic fabric design and its weavability in relation to the product performance of antiballistic fabric, gives free rein to get twice the results with half the effort. An effective parameter can then be supplied to a Computer Simulation Design to be used as a reference plan to increase ballistic fabric design. The particularity of national defense products which require reducing costs, raising efficiency, performing effective combat and putting into use quickly is addressed. This is a method to improve the performance of current basic materials.

The purpose of this paper is to optimize the design of the advanced combat helmet (ACH) currently in use, by its designers in order to attain maximum protection against ballistic impacts (fragments, shrapnel, etc.) and hard-surface/head collisions. Since traumatic brain injury experienced by a significant fraction of the soldiers returning from the recent conflicts is associated with their exposure to blast, the ACH should be redesigned in order to provide the necessary level of protection against blast loads. In the present work, augmentations of the ACH for improved blast protections are considered. These augmentations include the use of a polyurea (a nano-segregated elastomeric copolymer)-based ACH external coating/internal lining.

To demonstrate the efficacy of this approach, instrumented (unprotected, standard-ACH-protected, and augmented-ACH-protected) head-mannequin blast experiments are carried out. These experimental efforts are complemented with the appropriate combined Eulerian/Lagrangian transient non-linear dynamics computational fluid/solid interaction analysis.

The results obtained indicated that: when the extent of peak over-pressure reduction is used as a measure of the blast-mitigation effectiveness, polyurea-based augmentations do not noticeably improve, and sometimes slightly worsen, the performance of the standard ACH; when the extent of specific impulse reduction is used as a measure of the blast-mitigation effectiveness, application of the polyurea external coating to the standard ACH improves the blast-mitigation effectiveness of the helmet, particularly at shorter values of the charge-detonation standoff distance (SOD). At longer SODs, the effects of the polyurea-based ACH augmentations on the blast-mitigation efficacy of the standard ACH are inconclusive; and the use of the standard ACH significantly lowers the accelerations experienced by the skull and the intracranial matter. As far as the polyurea-based augmentations are concerned, only the internal lining at shorter SODs appears to yield additional reductions in the head accelerations.

To the authors’ knowledge, the present work contains the first report of a combined experimental/computational study addressing the problem of blast-mitigation by polyurea-based augmentation of ACH.

Conflict and violence are the main drivers of globally escalating humanitarian needs. Local grassroots initiatives are pivotal in distributing humanitarian supplies in the acute response phase until more established humanitarian aid organizations can enter. Nevertheless, scant research exists regarding the role of grassroots associations in providing humanitarian assistance during a military conflict. The purpose of this paper is to understand the role of grassroots associations and identify important themes for effective operations.

This paper adopts a case-study approach of three Ukrainian grassroots associations that began operating in the immediate days of the full-scale invasion of Ukraine. The findings are based on analyzing primary sources, including interviews with Ukrainian volunteers, and are supported by secondary sources.

Grassroots associations have local contacts and a contextual understanding of population needs and can respond more rapidly and effectively than large intergovernmental agencies. Four critical themes regarding the operations of grassroots associations emerged: information management, inventory management, coordination and performance measurement. Grassroots humanitarian response operations during conflict are challenged by personal security risks, the unpredictability of unsolicited supplies, emerging volunteer roles, dynamic transportation routes and shifting demands.

Grassroots responses are central to humanitarian responses during the acute phase of a military conflict. By examining the operations of grassroots associations in the early months of the 2022 war in Ukraine, the authors provide a unique perspective on humanitarian logistics. Nonetheless, more inclusive models of humanitarian responses are needed to harness the capacities and resilience of grassroots operations in practice.

In the speech in which he introduced the new Education Bill, Mr. H. A. L. Fisher remarked that it did not deal with a number of special questions, “which must be the matter of another measure.” One of these questions was “libraries,” and we are now definitely face to face with the fact that the Board of Education are of opinion that libraries are within their purview. The report of the speech as it appears in The Times is not conclusive upon the point. “Libiaries,” as an auxiliary of education, may connote in the Minister's mind the mere provision of libraries in schools and teaching institutions generally. If that is so there is no particular reason for alarm, so long as the authorities recognize that even the management of school libraries is a matter for librarians rather than for teachers.

The Prime Minister, the Rt Hon Mrs Margaret Thatcher FRS MP, arrived “Just in Time” to open a new one million litre paint distribution centre at the Trimite paint manufacturing complex at Uxbridge (Middlesex).

Combining the collected human body variables by a 3D body scanner and the research results of medical computed tomography (CT) imaging, this research aims to develop a military bulletproof vest that is both protective and fit. In particular, the protective part must be able to cover the vital human internal organs completely. The results of this research help to make military bulletproof vests of different sizes for Taiwanese male and female soldiers. At the same time, the research results can provide a reference for the industry of making special-purpose clothing.

17 important human body variables of 988 participants (male: 716, 72.5%; female 272, 27.5%) are used for the analysis. The K-means algorithm firstly builds clusters of different body shapes for both sexes; the silhouette coefficient helps to determine the optimal number of clusters to be six. Thus, the standard size of the bulletproof vest for soldiers is determined. The specifications of the bulletproof vest's inner core and textile vest are calculated for each cluster user. Our research then makes twelve prototypes of the bulletproof vest. After that, 12 subjects are invited to try on the new version (the vest designed in this study) and the old version (the vest currently used) to contrast the differences between the two.

According to the index of the silhouette coefficient, the optimal number of clusters is determined to be six for both male and female clusters. Therefore, this study has designed six sizes of the bulletproof vest for male and female soldiers in Taiwan. After trying the new and old vests on, the subjects all indicate that the new vest fits better than the old one. In addition, the coverage of the bulletproof vest designed in this study is 94.38% for male users and 92.75% for female users.

The design of bulletproof vests must take note of the fit of the clothing itself and its protective function. Apart from the size design of general clothing only focusing on the human shape exteriorly, the bulletproof vest also needs to pay attention to the relative positions of vital organs inside the human body. Besides, for practical applications, it is quite effective to use the silhouette coefficient to determine the results of cluster analysis. Thus, the value of this research lies in the cross-field combination, enabling the integration of body measurement, data science and clothing design. Generally, bulletproof vests of newly designed sizes can meet the requirements of Taiwan's military. The research results can be used in the development of various military clothing for Taiwanese military personnel. At the same time, the results can be provided to the clothing industry as relevant parameters for designing unique functional clothing.

A range of 5 basic types of industrial, all purpose, relays offer a choice of ac or dc coils ‐6A capacity. Operating at 2·4VA for ac and 1·2W dc, the D range conforms with accepted coil power requirements. High impact flame retardant moulding materials, with good insulation properties, are used throughout. Plug‐in types, with either solder or screw‐terminal sockets and panel mounted types suitable for either termination or Faston connectors, are both supplied with a clear polycarbonate clip‐on dust cover. A narrow profile of both the 2 pole and 3 pole plug‐in versions enables close stacking and consequently space saving with additional uniformity of appearance when mounted on an equipment panel.

The design of the Advanced Combat Helmet (ACH) currently in use was optimized by its designers in order to attain maximum protection against ballistic impacts (fragments, shrapnel, etc.) and hard-surface/head collisions. Since traumatic brain injury experienced by a significant fraction of the soldiers returning from the recent conflicts is associated with their exposure to blast, the ACH should be redesigned in order to provide the necessary level of protection against blast loads. The paper aims to discuss this issue.

In the present work, an augmentation of the ACH for improved blast protection is considered. This augmentation includes the use of a polyurea (a nano-segregated elastomeric copolymer) based ACH external coating. To demonstrate the efficacy of this approach, blast experiments are carried out on instrumented head-mannequins (without protection, protected using a standard ACH, and protected using an ACH augmented by a polyurea explosive-resistant coating (ERC)). These experimental efforts are complemented with the appropriate combined Eulerian/Lagrangian transient non-linear dynamics computational fluid/solid interaction finite-element analysis.

The results obtained clearly demonstrated that the use of an ERC on an ACH affects (generally in a beneficial way) head-mannequin dynamic loading and kinematic response as quantified by the intracranial pressure, impulse, acceleration and jolt.

To the authors’ knowledge, the present work is the first reported combined experimental/computational study of the blast-protection efficacy and the mild traumatic brain-injury mitigation potential of polyurea when used as an external coating on a helmet.